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vmalloc.c

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  • vmalloc.c 94.57 KiB
    /*
     *  linux/mm/vmalloc.c
     *
     *  Copyright (C) 1993  Linus Torvalds
     *  Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
     *  SMP-safe vmalloc/vfree/ioremap, Tigran Aivazian <tigran@veritas.com>, May 2000
     *  Major rework to support vmap/vunmap, Christoph Hellwig, SGI, August 2002
     *  Numa awareness, Christoph Lameter, SGI, June 2005
     */
    
    #include <linux/vmalloc.h>
    #include <linux/mm.h>
    #include <linux/module.h>
    #include <linux/highmem.h>
    #include <linux/sched/signal.h>
    #include <linux/slab.h>
    #include <linux/spinlock.h>
    #include <linux/interrupt.h>
    #include <linux/proc_fs.h>
    #include <linux/seq_file.h>
    #include <linux/debugobjects.h>
    #include <linux/kallsyms.h>
    #include <linux/list.h>
    #include <linux/notifier.h>
    #include <linux/rbtree.h>
    #include <linux/radix-tree.h>
    #include <linux/rcupdate.h>
    #include <linux/pfn.h>
    #include <linux/kmemleak.h>
    #include <linux/atomic.h>
    #include <linux/compiler.h>
    #include <linux/llist.h>
    #include <linux/bitops.h>
    #include <linux/overflow.h>
    #include <linux/rbtree_augmented.h>
    #include <linux/share_pool.h>
    
    #include <linux/uaccess.h>
    #include <asm/tlbflush.h>
    #include <asm/shmparam.h>
    #include <asm/pgtable.h>
    
    #include "internal.h"
    
    #ifdef CONFIG_HAVE_ARCH_HUGE_VMALLOC
    bool __ro_after_init vmap_allow_huge;
    
    static int __init set_nohugevmalloc(char *str)
    {
    	vmap_allow_huge = false;
    	return 0;
    }
    early_param("nohugevmalloc", set_nohugevmalloc);
    #else /* CONFIG_HAVE_ARCH_HUGE_VMALLOC */
    static const bool vmap_allow_huge;
    #endif	/* CONFIG_HAVE_ARCH_HUGE_VMALLOC */
    
    struct vfree_deferred {
    	struct llist_head list;
    	struct work_struct wq;
    };
    static DEFINE_PER_CPU(struct vfree_deferred, vfree_deferred);
    
    static void __vunmap(const void *, int);
    
    static void free_work(struct work_struct *w)
    {
    	struct vfree_deferred *p = container_of(w, struct vfree_deferred, wq);
    	struct llist_node *t, *llnode;
    
    	llist_for_each_safe(llnode, t, llist_del_all(&p->list))
    		__vunmap((void *)llnode, 1);
    }
    
    /*** Page table manipulation functions ***/
    static int vmap_pte_range(pmd_t *pmd, unsigned long addr,
    		unsigned long end, phys_addr_t phys_addr, pgprot_t prot)
    {
    	pte_t *pte;
    	u64 pfn;
    
    	pfn = phys_addr >> PAGE_SHIFT;
    	pte = pte_alloc_kernel(pmd, addr);
    	if (!pte)
    		return -ENOMEM;
    	do {
    		BUG_ON(!pte_none(*pte));
    		set_pte_at(&init_mm, addr, pte, pfn_pte(pfn, prot));
    		pfn++;
    	} while (pte++, addr += PAGE_SIZE, addr != end);
    	return 0;
    }
    
    static int vmap_try_huge_pmd(pmd_t *pmd, unsigned long addr, unsigned long end,
    			phys_addr_t phys_addr, pgprot_t prot,
    			unsigned int max_page_shift)
    {
    	if (max_page_shift < PMD_SHIFT)
    		return 0;
    
    	if (!arch_vmap_pmd_supported(prot))
    		return 0;
    
    	if ((end - addr) != PMD_SIZE)
    		return 0;
    
    	if (!IS_ALIGNED(phys_addr, PMD_SIZE))
    		return 0;
    
    	if (pmd_present(*pmd) && !pmd_free_pte_page(pmd, addr))
    		return 0;
    
    	return pmd_set_huge(pmd, phys_addr, prot);
    }
    
    static int vmap_pmd_range(pud_t *pud, unsigned long addr,
    		unsigned long end, phys_addr_t phys_addr, pgprot_t prot,
    		unsigned int max_page_shift)
    {
    	pmd_t *pmd;
    	unsigned long next;
    
    	pmd = pmd_alloc(&init_mm, pud, addr);
    	if (!pmd)
    		return -ENOMEM;
    	do {
    		next = pmd_addr_end(addr, end);
    
    		if (vmap_try_huge_pmd(pmd, addr, next, phys_addr, prot, max_page_shift))
    			continue;
    
    		if (vmap_pte_range(pmd, addr, next, phys_addr, prot))
    			return -ENOMEM;
    	} while (pmd++, phys_addr += (next - addr), addr = next, addr != end);
    	return 0;
    }
    
    static int vmap_try_huge_pud(pud_t *pud, unsigned long addr, unsigned long end,
    			phys_addr_t phys_addr, pgprot_t prot,
    			unsigned int max_page_shift)
    {
    	if (max_page_shift < PUD_SHIFT)
    		return 0;
    
    	if (!arch_vmap_pud_supported(prot))
    		return 0;
    
    	if ((end - addr) != PUD_SIZE)
    		return 0;
    
    	if (!IS_ALIGNED(phys_addr, PUD_SIZE))
    		return 0;
    
    	if (pud_present(*pud) && !pud_free_pmd_page(pud, addr))
    		return 0;
    
    	return pud_set_huge(pud, phys_addr, prot);
    }
    
    static int vmap_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end,
    			phys_addr_t phys_addr, pgprot_t prot,
    			unsigned int max_page_shift)
    {
    	pud_t *pud;
    	unsigned long next;
    
    	pud = pud_alloc(&init_mm, p4d, addr);
    	if (!pud)
    		return -ENOMEM;
    	do {
    		next = pud_addr_end(addr, end);
    
    		if (vmap_try_huge_pud(pud, addr, next, phys_addr, prot, max_page_shift))
    			continue;
    
    		if (vmap_pmd_range(pud, addr, next, phys_addr, prot, max_page_shift))
    			return -ENOMEM;
    	} while (pud++, phys_addr += (next - addr), addr = next, addr != end);
    	return 0;
    }
    
    static int vmap_try_huge_p4d(p4d_t *p4d, unsigned long addr, unsigned long end,
    			phys_addr_t phys_addr, pgprot_t prot,
    			unsigned int max_page_shift)
    {
    	if (max_page_shift < P4D_SHIFT)
    		return 0;
    
    	if (!arch_vmap_p4d_supported(prot))
    		return 0;
    
    	if ((end - addr) != P4D_SIZE)
    		return 0;
    
    	if (!IS_ALIGNED(phys_addr, P4D_SIZE))
    		return 0;
    
    	if (p4d_present(*p4d) && !p4d_free_pud_page(p4d, addr))
    		return 0;
    
    	return p4d_set_huge(p4d, phys_addr, prot);
    }
    
    static int vmap_p4d_range(pgd_t *pgd, unsigned long addr, unsigned long end,
    			phys_addr_t phys_addr, pgprot_t prot,
    			unsigned int max_page_shift)
    {
    	p4d_t *p4d;
    	unsigned long next;
    
    	p4d = p4d_alloc(&init_mm, pgd, addr);
    	if (!p4d)
    		return -ENOMEM;
    	do {
    		next = p4d_addr_end(addr, end);
    
    		if (vmap_try_huge_p4d(p4d, addr, next, phys_addr, prot, max_page_shift))
    			continue;
    
    		if (vmap_pud_range(p4d, addr, next, phys_addr, prot, max_page_shift))
    			return -ENOMEM;
    	} while (p4d++, phys_addr += (next - addr), addr = next, addr != end);
    	return 0;
    }
    
    static int vmap_range_noflush(unsigned long addr, unsigned long end,
    			phys_addr_t phys_addr, pgprot_t prot,
    			unsigned int max_page_shift)
    {
    	pgd_t *pgd;
    	unsigned long start;
    	unsigned long next;
    	int err;
    
    	might_sleep();
    	BUG_ON(addr >= end);
    
    	start = addr;
    	pgd = pgd_offset_k(addr);
    	do {
    		next = pgd_addr_end(addr, end);
    		err = vmap_p4d_range(pgd, addr, next, phys_addr, prot, max_page_shift);
    		if (err)
    			break;
    	} while (pgd++, phys_addr += (next - addr), addr = next, addr != end);
    
    	return err;
    }
    
    int vmap_range(unsigned long addr, unsigned long end,
    			phys_addr_t phys_addr, pgprot_t prot,
    			unsigned int max_page_shift)
    {
    	int err;
    
    	err = vmap_range_noflush(addr, end, phys_addr, prot, max_page_shift);
    	flush_cache_vmap(addr, end);
    
    	return err;
    }
    
    static void vunmap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end)
    {
    	pte_t *pte;
    
    	pte = pte_offset_kernel(pmd, addr);
    	do {
    		pte_t ptent = ptep_get_and_clear(&init_mm, addr, pte);
    		WARN_ON(!pte_none(ptent) && !pte_present(ptent));
    	} while (pte++, addr += PAGE_SIZE, addr != end);
    }
    
    static void vunmap_pmd_range(pud_t *pud, unsigned long addr, unsigned long end)
    {
    	pmd_t *pmd;
    	unsigned long next;
    
    	pmd = pmd_offset(pud, addr);
    	do {
    		next = pmd_addr_end(addr, end);
    		if (pmd_clear_huge(pmd))
    			continue;
    		if (pmd_none_or_clear_bad(pmd))
    			continue;
    		vunmap_pte_range(pmd, addr, next);
    	} while (pmd++, addr = next, addr != end);
    }
    
    static void vunmap_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end)
    {
    	pud_t *pud;
    	unsigned long next;
    
    	pud = pud_offset(p4d, addr);
    	do {
    		next = pud_addr_end(addr, end);
    		if (pud_clear_huge(pud))
    			continue;
    		if (pud_none_or_clear_bad(pud))
    			continue;
    		vunmap_pmd_range(pud, addr, next);
    	} while (pud++, addr = next, addr != end);
    }
    
    static void vunmap_p4d_range(pgd_t *pgd, unsigned long addr, unsigned long end)
    {
    	p4d_t *p4d;
    	unsigned long next;
    
    	p4d = p4d_offset(pgd, addr);
    	do {
    		next = p4d_addr_end(addr, end);
    		if (p4d_clear_huge(p4d))
    			continue;
    		if (p4d_none_or_clear_bad(p4d))
    			continue;
    		vunmap_pud_range(p4d, addr, next);
    	} while (p4d++, addr = next, addr != end);
    }
    
    /**
     * unmap_kernel_range_noflush - unmap kernel VM area
     * @addr: start of the VM area to unmap
     * @size: size of the VM area to unmap
     *
     * Unmap PFN_UP(@size) pages at @addr.  The VM area @addr and @size specify
     * should have been allocated using get_vm_area() and its friends.
     *
     * NOTE:
     * This function does NOT do any cache flushing.  The caller is responsible
     * for calling flush_cache_vunmap() on to-be-mapped areas before calling this
     * function and flush_tlb_kernel_range() after.
     */
    void unmap_kernel_range_noflush(unsigned long addr, unsigned long size)
    {
    	unsigned long end = addr + size;
    	unsigned long next;
    	pgd_t *pgd;
    
    	BUG_ON(addr >= end);
    	pgd = pgd_offset_k(addr);
    	do {
    		next = pgd_addr_end(addr, end);
    		if (pgd_none_or_clear_bad(pgd))
    			continue;
    		vunmap_p4d_range(pgd, addr, next);
    	} while (pgd++, addr = next, addr != end);
    }
    
    static int vmap_pages_pte_range(pmd_t *pmd, unsigned long addr,
    		unsigned long end, pgprot_t prot, struct page **pages, int *nr)
    {
    	pte_t *pte;
    
    	/*
    	 * nr is a running index into the array which helps higher level
    	 * callers keep track of where we're up to.
    	 */
    
    	pte = pte_alloc_kernel(pmd, addr);
    	if (!pte)
    		return -ENOMEM;
    	do {
    		struct page *page = pages[*nr];
    
    		if (WARN_ON(!pte_none(*pte)))
    			return -EBUSY;
    		if (WARN_ON(!page))
    			return -ENOMEM;
    		set_pte_at(&init_mm, addr, pte, mk_pte(page, prot));
    		(*nr)++;
    	} while (pte++, addr += PAGE_SIZE, addr != end);
    	return 0;
    }
    
    static int vmap_pages_pmd_range(pud_t *pud, unsigned long addr,
    		unsigned long end, pgprot_t prot, struct page **pages, int *nr)
    {
    	pmd_t *pmd;
    	unsigned long next;
    
    	pmd = pmd_alloc(&init_mm, pud, addr);
    	if (!pmd)
    		return -ENOMEM;
    	do {
    		next = pmd_addr_end(addr, end);
    		if (vmap_pages_pte_range(pmd, addr, next, prot, pages, nr))
    			return -ENOMEM;
    	} while (pmd++, addr = next, addr != end);
    	return 0;
    }
    
    static int vmap_pages_pud_range(p4d_t *p4d, unsigned long addr,
    		unsigned long end, pgprot_t prot, struct page **pages, int *nr)
    {
    	pud_t *pud;
    	unsigned long next;
    
    	pud = pud_alloc(&init_mm, p4d, addr);
    	if (!pud)
    		return -ENOMEM;
    	do {
    		next = pud_addr_end(addr, end);
    		if (vmap_pages_pmd_range(pud, addr, next, prot, pages, nr))
    			return -ENOMEM;
    	} while (pud++, addr = next, addr != end);
    	return 0;
    }
    
    static int vmap_pages_p4d_range(pgd_t *pgd, unsigned long addr,
    		unsigned long end, pgprot_t prot, struct page **pages, int *nr)
    {
    	p4d_t *p4d;
    	unsigned long next;
    
    	p4d = p4d_alloc(&init_mm, pgd, addr);
    	if (!p4d)
    		return -ENOMEM;
    	do {
    		next = p4d_addr_end(addr, end);
    		if (vmap_pages_pud_range(p4d, addr, next, prot, pages, nr))
    			return -ENOMEM;
    	} while (p4d++, addr = next, addr != end);
    	return 0;
    }
    
    static int vmap_small_pages_range_noflush(unsigned long addr, unsigned long end,
    		pgprot_t prot, struct page **pages)
    {
    	pgd_t *pgd;
    	unsigned long next;
    	int err = 0;
    	int nr = 0;
    
    	BUG_ON(addr >= end);
    	pgd = pgd_offset_k(addr);
    	do {
    		next = pgd_addr_end(addr, end);
    		err = vmap_pages_p4d_range(pgd, addr, next, prot, pages, &nr);
    		if (err)
    			return err;
    	} while (pgd++, addr = next, addr != end);
    
    	return 0;
    }
    
    static int vmap_pages_range_noflush(unsigned long addr, unsigned long end,
    		pgprot_t prot, struct page **pages, unsigned int page_shift)
    {
    	unsigned int i, nr = (end - addr) >> PAGE_SHIFT;
    
    	WARN_ON(page_shift < PAGE_SHIFT);
    
    	if (page_shift == PAGE_SHIFT)
    		return vmap_small_pages_range_noflush(addr, end, prot, pages);
    
    	for (i = 0; i < nr; i += 1U << (page_shift - PAGE_SHIFT)) {
    		int err;
    
    		err = vmap_range_noflush(addr, addr + (1UL << page_shift),
    					__pa(page_address(pages[i])), prot,
    					page_shift);
    		if (err)
    			return err;
    
    		addr += 1UL << page_shift;
    	}
    
    	return 0;
    }
    
    static int vmap_pages_range(unsigned long addr, unsigned long end,
    		pgprot_t prot, struct page **pages, unsigned int page_shift)
    {
    	int err;
    
    	err = vmap_pages_range_noflush(addr, end, prot, pages, page_shift);
    	flush_cache_vmap(addr, end);
    	return err;
    }
    
    static int vmap_hugepages_range_noflush(unsigned long addr, unsigned long end,
    		pgprot_t prot, struct page **pages, unsigned int page_shift)
    {
    	unsigned int i, nr = (end - addr) >> page_shift;
    
    	for (i = 0; i < nr; i++) {
    		int err;
    
    		err = vmap_range_noflush(addr, addr + (1UL << page_shift),
    					__pa(page_address(pages[i])), prot,
    					page_shift);
    		if (err)
    			return err;
    
    		addr += 1UL << page_shift;
    	}
    
    	return 0;
    }
    
    static int vmap_hugepages_range(unsigned long addr, unsigned long end,
    				pgprot_t prot, struct page **pages,
    				unsigned int page_shift)
    {
    	int err;
    
    	err = vmap_hugepages_range_noflush(addr, end, prot, pages, page_shift);
    	flush_cache_vmap(addr, end);
    	return err;
    }
    
    /**
     * map_kernel_range_noflush - map kernel VM area with the specified pages
     * @addr: start of the VM area to map
     * @size: size of the VM area to map
     * @prot: page protection flags to use
     * @pages: pages to map
     *
     * Map PFN_UP(@size) pages at @addr.  The VM area @addr and @size specify should
     * have been allocated using get_vm_area() and its friends.
     *
     * NOTE:
     * This function does NOT do any cache flushing.  The caller is responsible for
     * calling flush_cache_vmap() on to-be-mapped areas before calling this
     * function.
     *
     * RETURNS:
     * 0 on success, -errno on failure.
     */
    int map_kernel_range_noflush(unsigned long addr, unsigned long size,
    			     pgprot_t prot, struct page **pages)
    {
    	return vmap_pages_range_noflush(addr, addr + size, prot, pages, PAGE_SHIFT);
    }
    
    int map_kernel_range(unsigned long start, unsigned long size, pgprot_t prot,
    		struct page **pages)
    {
    	int ret;
    
    	ret = map_kernel_range_noflush(start, size, prot, pages);
    	flush_cache_vmap(start, start + size);
    	return ret;
    }
    
    int is_vmalloc_or_module_addr(const void *x)
    {
    	/*
    	 * ARM, x86-64 and sparc64 put modules in a special place,
    	 * and fall back on vmalloc() if that fails. Others
    	 * just put it in the vmalloc space.
    	 */
    #if defined(CONFIG_MODULES) && defined(MODULES_VADDR)
    	unsigned long addr = (unsigned long)x;
    	if (addr >= MODULES_VADDR && addr < MODULES_END)
    		return 1;
    #endif
    	return is_vmalloc_addr(x);
    }
    
    /*
     * Walk a vmap address to the struct page it maps. Huge vmap mappings will
     * return the tail page that corresponds to the base page address, which
     * matches small vmap mappings.
     */
    struct page *vmalloc_to_page(const void *vmalloc_addr)
    {
    	unsigned long addr = (unsigned long) vmalloc_addr;
    	struct page *page = NULL;
    	pgd_t *pgd = pgd_offset_k(addr);
    	p4d_t *p4d;
    	pud_t *pud;
    	pmd_t *pmd;
    	pte_t *ptep, pte;
    
    	/*
    	 * XXX we might need to change this if we add VIRTUAL_BUG_ON for
    	 * architectures that do not vmalloc module space
    	 */
    	VIRTUAL_BUG_ON(!is_vmalloc_or_module_addr(vmalloc_addr));
    
    	if (pgd_none(*pgd))
    		return NULL;
    	if (WARN_ON_ONCE(pgd_leaf(*pgd)))
    		return NULL; /* XXX: no allowance for huge pgd */
    	if (WARN_ON_ONCE(pgd_bad(*pgd)))
    		return NULL;
    
    	p4d = p4d_offset(pgd, addr);
    	if (p4d_none(*p4d))
    		return NULL;
    	if (p4d_leaf(*p4d))
    		return p4d_page(*p4d) + ((addr & ~P4D_MASK) >> PAGE_SHIFT);
    	if (WARN_ON_ONCE(p4d_bad(*p4d)))
    		return NULL;
    
    	pud = pud_offset(p4d, addr);
    	if (pud_none(*pud))
    		return NULL;
    	if (pud_leaf(*pud))
    		return pud_page(*pud) + ((addr & ~PUD_MASK) >> PAGE_SHIFT);
    	if (WARN_ON_ONCE(pud_bad(*pud)))
    		return NULL;
    
    	pmd = pmd_offset(pud, addr);
    	if (pmd_none(*pmd))
    		return NULL;
    	if (pmd_leaf(*pmd))
    		return pmd_page(*pmd) + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
    	if (WARN_ON_ONCE(pmd_bad(*pmd)))
    		return NULL;
    
    	ptep = pte_offset_map(pmd, addr);
    	pte = *ptep;
    	if (pte_present(pte))
    		page = pte_page(pte);
    	pte_unmap(ptep);
    
    	return page;
    }
    EXPORT_SYMBOL(vmalloc_to_page);
    
    /*
     * Walk a hugepage vmap address to the struct page it maps.
     * return the head page that corresponds to the base page address.
     */
    struct page *vmalloc_to_hugepage(const void *vmalloc_addr)
    {
    	struct page *huge;
    
    	huge = vmalloc_to_page(vmalloc_addr);
    	if (huge && PageHuge(huge))
    		return huge;
    	else
    		return NULL;
    }
    EXPORT_SYMBOL(vmalloc_to_hugepage);
    
    /*
     * Map a vmalloc()-space virtual address to the physical page frame number.
     */
    unsigned long vmalloc_to_pfn(const void *vmalloc_addr)
    {
    	return page_to_pfn(vmalloc_to_page(vmalloc_addr));
    }
    EXPORT_SYMBOL(vmalloc_to_pfn);
    
    
    /*** Global kva allocator ***/
    
    #define DEBUG_AUGMENT_PROPAGATE_CHECK 0
    #define DEBUG_AUGMENT_LOWEST_MATCH_CHECK 0
    
    #define VM_LAZY_FREE	0x02
    #define VM_VM_AREA	0x04
    
    static DEFINE_SPINLOCK(vmap_area_lock);
    /* Export for kexec only */
    LIST_HEAD(vmap_area_list);
    static LLIST_HEAD(vmap_purge_list);
    static struct rb_root vmap_area_root = RB_ROOT;
    static bool vmap_initialized __read_mostly;
    
    /*
     * This kmem_cache is used for vmap_area objects. Instead of
     * allocating from slab we reuse an object from this cache to
     * make things faster. Especially in "no edge" splitting of
     * free block.
     */
    static struct kmem_cache *vmap_area_cachep;
    
    /*
     * This linked list is used in pair with free_vmap_area_root.
     * It gives O(1) access to prev/next to perform fast coalescing.
     */
    static LIST_HEAD(free_vmap_area_list);
    
    /*
     * This augment red-black tree represents the free vmap space.
     * All vmap_area objects in this tree are sorted by va->va_start
     * address. It is used for allocation and merging when a vmap
     * object is released.
     *
     * Each vmap_area node contains a maximum available free block
     * of its sub-tree, right or left. Therefore it is possible to
     * find a lowest match of free area.
     */
    static struct rb_root free_vmap_area_root = RB_ROOT;
    
    static __always_inline unsigned long
    va_size(struct vmap_area *va)
    {
    	return (va->va_end - va->va_start);
    }
    
    static __always_inline unsigned long
    get_subtree_max_size(struct rb_node *node)
    {
    	struct vmap_area *va;
    
    	va = rb_entry_safe(node, struct vmap_area, rb_node);
    	return va ? va->subtree_max_size : 0;
    }
    
    /*
     * Gets called when remove the node and rotate.
     */
    static __always_inline unsigned long
    compute_subtree_max_size(struct vmap_area *va)
    {
    	return max3(va_size(va),
    		get_subtree_max_size(va->rb_node.rb_left),
    		get_subtree_max_size(va->rb_node.rb_right));
    }
    
    RB_DECLARE_CALLBACKS(static, free_vmap_area_rb_augment_cb,
    	struct vmap_area, rb_node, unsigned long, subtree_max_size,
    	compute_subtree_max_size)
    
    static void purge_vmap_area_lazy(void);
    static BLOCKING_NOTIFIER_HEAD(vmap_notify_list);
    static unsigned long lazy_max_pages(void);
    
    static struct vmap_area *__find_vmap_area(unsigned long addr)
    {
    	struct rb_node *n = vmap_area_root.rb_node;
    
    	while (n) {
    		struct vmap_area *va;
    
    		va = rb_entry(n, struct vmap_area, rb_node);
    		if (addr < va->va_start)
    			n = n->rb_left;
    		else if (addr >= va->va_end)
    			n = n->rb_right;
    		else
    			return va;
    	}
    
    	return NULL;
    }
    
    /*
     * This function returns back addresses of parent node
     * and its left or right link for further processing.
     */
    static __always_inline struct rb_node **
    find_va_links(struct vmap_area *va,
    	struct rb_root *root, struct rb_node *from,
    	struct rb_node **parent)
    {
    	struct vmap_area *tmp_va;
    	struct rb_node **link;
    
    	if (root) {
    		link = &root->rb_node;
    		if (unlikely(!*link)) {
    			*parent = NULL;
    			return link;
    		}
    	} else {
    		link = &from;
    	}
    
    	/*
    	 * Go to the bottom of the tree. When we hit the last point
    	 * we end up with parent rb_node and correct direction, i name
    	 * it link, where the new va->rb_node will be attached to.
    	 */
    	do {
    		tmp_va = rb_entry(*link, struct vmap_area, rb_node);
    
    		/*
    		 * During the traversal we also do some sanity check.
    		 * Trigger the BUG() if there are sides(left/right)
    		 * or full overlaps.
    		 */
    		if (va->va_start < tmp_va->va_end &&
    				va->va_end <= tmp_va->va_start)
    			link = &(*link)->rb_left;
    		else if (va->va_end > tmp_va->va_start &&
    				va->va_start >= tmp_va->va_end)
    			link = &(*link)->rb_right;
    		else
    			BUG();
    	} while (*link);
    
    	*parent = &tmp_va->rb_node;
    	return link;
    }
    
    static __always_inline struct list_head *
    get_va_next_sibling(struct rb_node *parent, struct rb_node **link)
    {
    	struct list_head *list;
    
    	if (unlikely(!parent))
    		/*
    		 * The red-black tree where we try to find VA neighbors
    		 * before merging or inserting is empty, i.e. it means
    		 * there is no free vmap space. Normally it does not
    		 * happen but we handle this case anyway.
    		 */
    		return NULL;
    
    	list = &rb_entry(parent, struct vmap_area, rb_node)->list;
    	return (&parent->rb_right == link ? list->next : list);
    }
    
    static __always_inline void
    link_va(struct vmap_area *va, struct rb_root *root,
    	struct rb_node *parent, struct rb_node **link, struct list_head *head)
    {
    	/*
    	 * VA is still not in the list, but we can
    	 * identify its future previous list_head node.
    	 */
    	if (likely(parent)) {
    		head = &rb_entry(parent, struct vmap_area, rb_node)->list;
    		if (&parent->rb_right != link)
    			head = head->prev;
    	}
    
    	/* Insert to the rb-tree */
    	rb_link_node(&va->rb_node, parent, link);
    	if (root == &free_vmap_area_root) {
    		/*
    		 * Some explanation here. Just perform simple insertion
    		 * to the tree. We do not set va->subtree_max_size to
    		 * its current size before calling rb_insert_augmented().
    		 * It is because of we populate the tree from the bottom
    		 * to parent levels when the node _is_ in the tree.
    		 *
    		 * Therefore we set subtree_max_size to zero after insertion,
    		 * to let __augment_tree_propagate_from() puts everything to
    		 * the correct order later on.
    		 */
    		rb_insert_augmented(&va->rb_node,
    			root, &free_vmap_area_rb_augment_cb);
    		va->subtree_max_size = 0;
    	} else {
    		rb_insert_color(&va->rb_node, root);
    	}
    
    	/* Address-sort this list */
    	list_add(&va->list, head);
    }
    
    static __always_inline void
    unlink_va(struct vmap_area *va, struct rb_root *root)
    {
    	/*
    	 * During merging a VA node can be empty, therefore
    	 * not linked with the tree nor list. Just check it.
    	 */
    	if (!RB_EMPTY_NODE(&va->rb_node)) {
    		if (root == &free_vmap_area_root)
    			rb_erase_augmented(&va->rb_node,
    				root, &free_vmap_area_rb_augment_cb);
    		else
    			rb_erase(&va->rb_node, root);
    
    		list_del(&va->list);
    		RB_CLEAR_NODE(&va->rb_node);
    	}
    }
    
    #if DEBUG_AUGMENT_PROPAGATE_CHECK
    static void
    augment_tree_propagate_check(struct rb_node *n)
    {
    	struct vmap_area *va;
    	struct rb_node *node;
    	unsigned long size;
    	bool found = false;
    
    	if (n == NULL)
    		return;
    
    	va = rb_entry(n, struct vmap_area, rb_node);
    	size = va->subtree_max_size;
    	node = n;
    
    	while (node) {
    		va = rb_entry(node, struct vmap_area, rb_node);
    
    		if (get_subtree_max_size(node->rb_left) == size) {
    			node = node->rb_left;
    		} else {
    			if (va_size(va) == size) {
    				found = true;
    				break;
    			}
    
    			node = node->rb_right;
    		}
    	}
    
    	if (!found) {
    		va = rb_entry(n, struct vmap_area, rb_node);
    		pr_emerg("tree is corrupted: %lu, %lu\n",
    			va_size(va), va->subtree_max_size);
    	}
    
    	augment_tree_propagate_check(n->rb_left);
    	augment_tree_propagate_check(n->rb_right);
    }
    #endif
    
    /*
     * This function populates subtree_max_size from bottom to upper
     * levels starting from VA point. The propagation must be done
     * when VA size is modified by changing its va_start/va_end. Or
     * in case of newly inserting of VA to the tree.
     *
     * It means that __augment_tree_propagate_from() must be called:
     * - After VA has been inserted to the tree(free path);
     * - After VA has been shrunk(allocation path);
     * - After VA has been increased(merging path).
     *
     * Please note that, it does not mean that upper parent nodes
     * and their subtree_max_size are recalculated all the time up
     * to the root node.
     *
     *       4--8
     *        /\
     *       /  \
     *      /    \
     *    2--2  8--8
     *
     * For example if we modify the node 4, shrinking it to 2, then
     * no any modification is required. If we shrink the node 2 to 1
     * its subtree_max_size is updated only, and set to 1. If we shrink
     * the node 8 to 6, then its subtree_max_size is set to 6 and parent
     * node becomes 4--6.
     */
    static __always_inline void
    augment_tree_propagate_from(struct vmap_area *va)
    {
    	struct rb_node *node = &va->rb_node;
    	unsigned long new_va_sub_max_size;
    
    	while (node) {
    		va = rb_entry(node, struct vmap_area, rb_node);
    		new_va_sub_max_size = compute_subtree_max_size(va);
    
    		/*
    		 * If the newly calculated maximum available size of the
    		 * subtree is equal to the current one, then it means that
    		 * the tree is propagated correctly. So we have to stop at
    		 * this point to save cycles.
    		 */
    		if (va->subtree_max_size == new_va_sub_max_size)
    			break;
    
    		va->subtree_max_size = new_va_sub_max_size;
    		node = rb_parent(&va->rb_node);
    	}
    
    #if DEBUG_AUGMENT_PROPAGATE_CHECK
    	augment_tree_propagate_check(free_vmap_area_root.rb_node);
    #endif
    }
    
    static void
    insert_vmap_area(struct vmap_area *va,
    	struct rb_root *root, struct list_head *head)
    {
    	struct rb_node **link;
    	struct rb_node *parent;
    
    	link = find_va_links(va, root, NULL, &parent);
    	link_va(va, root, parent, link, head);
    }
    
    static void
    insert_vmap_area_augment(struct vmap_area *va,
    	struct rb_node *from, struct rb_root *root,
    	struct list_head *head)
    {
    	struct rb_node **link;
    	struct rb_node *parent;
    
    	if (from)
    		link = find_va_links(va, NULL, from, &parent);
    	else
    		link = find_va_links(va, root, NULL, &parent);
    
    	link_va(va, root, parent, link, head);
    	augment_tree_propagate_from(va);
    }
    
    /*
     * Merge de-allocated chunk of VA memory with previous
     * and next free blocks. If coalesce is not done a new
     * free area is inserted. If VA has been merged, it is
     * freed.
     */
    static __always_inline void
    merge_or_add_vmap_area(struct vmap_area *va,
    	struct rb_root *root, struct list_head *head)
    {
    	struct vmap_area *sibling;
    	struct list_head *next;
    	struct rb_node **link;
    	struct rb_node *parent;
    	bool merged = false;
    
    	/*
    	 * Find a place in the tree where VA potentially will be
    	 * inserted, unless it is merged with its sibling/siblings.
    	 */
    	link = find_va_links(va, root, NULL, &parent);
    
    	/*
    	 * Get next node of VA to check if merging can be done.
    	 */
    	next = get_va_next_sibling(parent, link);
    	if (unlikely(next == NULL))
    		goto insert;
    
    	/*
    	 * start            end
    	 * |                |
    	 * |<------VA------>|<-----Next----->|
    	 *                  |                |
    	 *                  start            end
    	 */
    	if (next != head) {
    		sibling = list_entry(next, struct vmap_area, list);
    		if (sibling->va_start == va->va_end) {
    			sibling->va_start = va->va_start;
    
    			/* Check and update the tree if needed. */
    			augment_tree_propagate_from(sibling);
    
    			/* Remove this VA, it has been merged. */
    			unlink_va(va, root);
    
    			/* Free vmap_area object. */
    			kmem_cache_free(vmap_area_cachep, va);
    
    			/* Point to the new merged area. */
    			va = sibling;
    			merged = true;
    		}
    	}
    
    	/*
    	 * start            end
    	 * |                |
    	 * |<-----Prev----->|<------VA------>|
    	 *                  |                |
    	 *                  start            end
    	 */
    	if (next->prev != head) {
    		sibling = list_entry(next->prev, struct vmap_area, list);
    		if (sibling->va_end == va->va_start) {
    			sibling->va_end = va->va_end;
    
    			/* Check and update the tree if needed. */
    			augment_tree_propagate_from(sibling);
    
    			/* Remove this VA, it has been merged. */
    			unlink_va(va, root);
    
    			/* Free vmap_area object. */
    			kmem_cache_free(vmap_area_cachep, va);
    
    			return;
    		}
    	}
    
    insert:
    	if (!merged) {
    		link_va(va, root, parent, link, head);
    		augment_tree_propagate_from(va);
    	}
    }
    
    static __always_inline bool
    is_within_this_va(struct vmap_area *va, unsigned long size,
    	unsigned long align, unsigned long vstart)
    {
    	unsigned long nva_start_addr;
    
    	if (va->va_start > vstart)
    		nva_start_addr = ALIGN(va->va_start, align);
    	else
    		nva_start_addr = ALIGN(vstart, align);
    
    	/* Can be overflowed due to big size or alignment. */
    	if (nva_start_addr + size < nva_start_addr ||
    			nva_start_addr < vstart)
    		return false;
    
    	return (nva_start_addr + size <= va->va_end);
    }
    
    /*
     * Find the first free block(lowest start address) in the tree,
     * that will accomplish the request corresponding to passing
     * parameters.
     */
    static __always_inline struct vmap_area *
    find_vmap_lowest_match(unsigned long size,
    	unsigned long align, unsigned long vstart)
    {
    	struct vmap_area *va;
    	struct rb_node *node;
    	unsigned long length;
    
    	/* Start from the root. */
    	node = free_vmap_area_root.rb_node;
    
    	/* Adjust the search size for alignment overhead. */
    	length = size + align - 1;
    
    	while (node) {
    		va = rb_entry(node, struct vmap_area, rb_node);
    
    		if (get_subtree_max_size(node->rb_left) >= length &&
    				vstart < va->va_start) {
    			node = node->rb_left;
    		} else {
    			if (is_within_this_va(va, size, align, vstart))
    				return va;
    
    			/*
    			 * Does not make sense to go deeper towards the right
    			 * sub-tree if it does not have a free block that is
    			 * equal or bigger to the requested search length.
    			 */
    			if (get_subtree_max_size(node->rb_right) >= length) {
    				node = node->rb_right;
    				continue;
    			}
    
    			/*
    			 * OK. We roll back and find the fist right sub-tree,
    			 * that will satisfy the search criteria. It can happen
    			 * only once due to "vstart" restriction.
    			 */
    			while ((node = rb_parent(node))) {
    				va = rb_entry(node, struct vmap_area, rb_node);
    				if (is_within_this_va(va, size, align, vstart))
    					return va;
    
    				if (get_subtree_max_size(node->rb_right) >= length &&
    						vstart <= va->va_start) {
    					node = node->rb_right;
    					break;
    				}
    			}
    		}
    	}
    
    	return NULL;
    }
    
    #if DEBUG_AUGMENT_LOWEST_MATCH_CHECK
    #include <linux/random.h>
    
    static struct vmap_area *
    find_vmap_lowest_linear_match(unsigned long size,
    	unsigned long align, unsigned long vstart)
    {
    	struct vmap_area *va;
    
    	list_for_each_entry(va, &free_vmap_area_list, list) {
    		if (!is_within_this_va(va, size, align, vstart))
    			continue;
    
    		return va;
    	}
    
    	return NULL;
    }
    
    static void
    find_vmap_lowest_match_check(unsigned long size)
    {
    	struct vmap_area *va_1, *va_2;
    	unsigned long vstart;
    	unsigned int rnd;
    
    	get_random_bytes(&rnd, sizeof(rnd));
    	vstart = VMALLOC_START + rnd;
    
    	va_1 = find_vmap_lowest_match(size, 1, vstart);
    	va_2 = find_vmap_lowest_linear_match(size, 1, vstart);
    
    	if (va_1 != va_2)
    		pr_emerg("not lowest: t: 0x%p, l: 0x%p, v: 0x%lx\n",
    			va_1, va_2, vstart);
    }
    #endif
    
    enum fit_type {
    	NOTHING_FIT = 0,
    	FL_FIT_TYPE = 1,	/* full fit */
    	LE_FIT_TYPE = 2,	/* left edge fit */
    	RE_FIT_TYPE = 3,	/* right edge fit */
    	NE_FIT_TYPE = 4		/* no edge fit */
    };
    
    static __always_inline enum fit_type
    classify_va_fit_type(struct vmap_area *va,
    	unsigned long nva_start_addr, unsigned long size)
    {
    	enum fit_type type;
    
    	/* Check if it is within VA. */
    	if (nva_start_addr < va->va_start ||
    			nva_start_addr + size > va->va_end)
    		return NOTHING_FIT;
    
    	/* Now classify. */
    	if (va->va_start == nva_start_addr) {
    		if (va->va_end == nva_start_addr + size)
    			type = FL_FIT_TYPE;
    		else
    			type = LE_FIT_TYPE;
    	} else if (va->va_end == nva_start_addr + size) {
    		type = RE_FIT_TYPE;
    	} else {
    		type = NE_FIT_TYPE;
    	}
    
    	return type;
    }
    
    static __always_inline int
    adjust_va_to_fit_type(struct vmap_area *va,
    	unsigned long nva_start_addr, unsigned long size,
    	enum fit_type type)
    {
    	struct vmap_area *lva = NULL;
    
    	if (type == FL_FIT_TYPE) {
    		/*
    		 * No need to split VA, it fully fits.
    		 *
    		 * |               |
    		 * V      NVA      V
    		 * |---------------|
    		 */
    		unlink_va(va, &free_vmap_area_root);
    		kmem_cache_free(vmap_area_cachep, va);
    	} else if (type == LE_FIT_TYPE) {
    		/*
    		 * Split left edge of fit VA.
    		 *
    		 * |       |
    		 * V  NVA  V   R
    		 * |-------|-------|
    		 */
    		va->va_start += size;
    	} else if (type == RE_FIT_TYPE) {
    		/*
    		 * Split right edge of fit VA.
    		 *
    		 *         |       |
    		 *     L   V  NVA  V
    		 * |-------|-------|
    		 */
    		va->va_end = nva_start_addr;
    	} else if (type == NE_FIT_TYPE) {
    		/*
    		 * Split no edge of fit VA.
    		 *
    		 *     |       |
    		 *   L V  NVA  V R
    		 * |---|-------|---|
    		 */
    		lva = kmem_cache_alloc(vmap_area_cachep, GFP_NOWAIT);
    		if (unlikely(!lva))
    			return -1;
    
    		/*
    		 * Build the remainder.
    		 */
    		lva->va_start = va->va_start;
    		lva->va_end = nva_start_addr;
    
    		/*
    		 * Shrink this VA to remaining size.
    		 */
    		va->va_start = nva_start_addr + size;
    	} else {
    		return -1;
    	}
    
    	if (type != FL_FIT_TYPE) {
    		augment_tree_propagate_from(va);
    
    		if (lva)	/* type == NE_FIT_TYPE */
    			insert_vmap_area_augment(lva, &va->rb_node,
    				&free_vmap_area_root, &free_vmap_area_list);
    	}
    
    	return 0;
    }
    
    /*
     * Returns a start address of the newly allocated area, if success.
     * Otherwise a vend is returned that indicates failure.
     */
    static __always_inline unsigned long
    __alloc_vmap_area(unsigned long size, unsigned long align,
    	unsigned long vstart, unsigned long vend, int node)
    {
    	unsigned long nva_start_addr;
    	struct vmap_area *va;
    	enum fit_type type;
    	int ret;
    
    	va = find_vmap_lowest_match(size, align, vstart);
    	if (unlikely(!va))
    		return vend;
    
    	if (va->va_start > vstart)
    		nva_start_addr = ALIGN(va->va_start, align);
    	else
    		nva_start_addr = ALIGN(vstart, align);
    
    	/* Check the "vend" restriction. */
    	if (nva_start_addr + size > vend)
    		return vend;
    
    	/* Classify what we have found. */
    	type = classify_va_fit_type(va, nva_start_addr, size);
    	if (WARN_ON_ONCE(type == NOTHING_FIT))
    		return vend;
    
    	/* Update the free vmap_area. */
    	ret = adjust_va_to_fit_type(va, nva_start_addr, size, type);
    	if (ret)
    		return vend;
    
    #if DEBUG_AUGMENT_LOWEST_MATCH_CHECK
    	find_vmap_lowest_match_check(size);
    #endif
    
    	return nva_start_addr;
    }
    
    /*
     * Allocate a region of KVA of the specified size and alignment, within the
     * vstart and vend.
     */
    static struct vmap_area *alloc_vmap_area(unsigned long size,
    				unsigned long align,
    				unsigned long vstart, unsigned long vend,
    				int node, gfp_t gfp_mask)
    {
    	struct vmap_area *va;
    	unsigned long addr;
    	int purged = 0;
    
    	BUG_ON(!size);
    	BUG_ON(offset_in_page(size));
    	BUG_ON(!is_power_of_2(align));
    
    	if (unlikely(!vmap_initialized))
    		return ERR_PTR(-EBUSY);
    
    	might_sleep();
    
    	va = kmem_cache_alloc_node(vmap_area_cachep,
    			gfp_mask & GFP_RECLAIM_MASK, node);
    	if (unlikely(!va))
    		return ERR_PTR(-ENOMEM);
    
    	/*
    	 * Only scan the relevant parts containing pointers to other objects
    	 * to avoid false negatives.
    	 */
    	kmemleak_scan_area(&va->rb_node, SIZE_MAX, gfp_mask & GFP_RECLAIM_MASK);
    
    retry:
    	spin_lock(&vmap_area_lock);
    
    	/*
    	 * If an allocation fails, the "vend" address is
    	 * returned. Therefore trigger the overflow path.
    	 */
    	addr = __alloc_vmap_area(size, align, vstart, vend, node);
    	if (unlikely(addr == vend))
    		goto overflow;
    
    	va->va_start = addr;
    	va->va_end = addr + size;
    	va->flags = 0;
    	insert_vmap_area(va, &vmap_area_root, &vmap_area_list);
    
    	spin_unlock(&vmap_area_lock);
    
    	BUG_ON(!IS_ALIGNED(va->va_start, align));
    	BUG_ON(va->va_start < vstart);
    	BUG_ON(va->va_end > vend);
    
    	return va;
    
    overflow:
    	spin_unlock(&vmap_area_lock);
    	if (!purged) {
    		purge_vmap_area_lazy();
    		purged = 1;
    		goto retry;
    	}
    
    	if (gfpflags_allow_blocking(gfp_mask)) {
    		unsigned long freed = 0;
    		blocking_notifier_call_chain(&vmap_notify_list, 0, &freed);
    		if (freed > 0) {
    			purged = 0;
    			goto retry;
    		}
    	}
    
    	if (!(gfp_mask & __GFP_NOWARN) && printk_ratelimit())
    		pr_warn("vmap allocation for size %lu failed: use vmalloc=<size> to increase size\n",
    			size);
    
    	kmem_cache_free(vmap_area_cachep, va);
    	return ERR_PTR(-EBUSY);
    }
    
    int register_vmap_purge_notifier(struct notifier_block *nb)
    {
    	return blocking_notifier_chain_register(&vmap_notify_list, nb);
    }
    EXPORT_SYMBOL_GPL(register_vmap_purge_notifier);
    
    int unregister_vmap_purge_notifier(struct notifier_block *nb)
    {
    	return blocking_notifier_chain_unregister(&vmap_notify_list, nb);
    }
    EXPORT_SYMBOL_GPL(unregister_vmap_purge_notifier);
    
    static void __free_vmap_area(struct vmap_area *va)
    {
    	BUG_ON(RB_EMPTY_NODE(&va->rb_node));
    
    	/*
    	 * Remove from the busy tree/list.
    	 */
    	unlink_va(va, &vmap_area_root);
    
    	/*
    	 * Merge VA with its neighbors, otherwise just add it.
    	 */
    	merge_or_add_vmap_area(va,
    		&free_vmap_area_root, &free_vmap_area_list);
    }
    
    /*
     * Free a region of KVA allocated by alloc_vmap_area
     */
    static void free_vmap_area(struct vmap_area *va)
    {
    	spin_lock(&vmap_area_lock);
    	__free_vmap_area(va);
    	spin_unlock(&vmap_area_lock);
    }
    
    /*
     * Clear the pagetable entries of a given vmap_area
     */
    static void unmap_vmap_area(struct vmap_area *va)
    {
    	unmap_kernel_range_noflush(va->va_start, va->va_end - va->va_start);
    }
    
    /*
     * lazy_max_pages is the maximum amount of virtual address space we gather up
     * before attempting to purge with a TLB flush.
     *
     * There is a tradeoff here: a larger number will cover more kernel page tables
     * and take slightly longer to purge, but it will linearly reduce the number of
     * global TLB flushes that must be performed. It would seem natural to scale
     * this number up linearly with the number of CPUs (because vmapping activity
     * could also scale linearly with the number of CPUs), however it is likely
     * that in practice, workloads might be constrained in other ways that mean
     * vmap activity will not scale linearly with CPUs. Also, I want to be
     * conservative and not introduce a big latency on huge systems, so go with
     * a less aggressive log scale. It will still be an improvement over the old
     * code, and it will be simple to change the scale factor if we find that it
     * becomes a problem on bigger systems.
     */
    static unsigned long lazy_max_pages(void)
    {
    	unsigned int log;
    
    	log = fls(num_online_cpus());
    
    	return log * (32UL * 1024 * 1024 / PAGE_SIZE);
    }
    
    static atomic_t vmap_lazy_nr = ATOMIC_INIT(0);
    
    /*
     * Serialize vmap purging.  There is no actual criticial section protected
     * by this look, but we want to avoid concurrent calls for performance
     * reasons and to make the pcpu_get_vm_areas more deterministic.
     */
    static DEFINE_MUTEX(vmap_purge_lock);
    
    /* for per-CPU blocks */
    static void purge_fragmented_blocks_allcpus(void);
    
    /*
     * called before a call to iounmap() if the caller wants vm_area_struct's
     * immediately freed.
     */
    void set_iounmap_nonlazy(void)
    {
    	atomic_set(&vmap_lazy_nr, lazy_max_pages()+1);
    }
    
    /*
     * Purges all lazily-freed vmap areas.
     */
    static bool __purge_vmap_area_lazy(unsigned long start, unsigned long end)
    {
    	struct llist_node *valist;
    	struct vmap_area *va;
    	struct vmap_area *n_va;
    	bool do_free = false;
    
    	lockdep_assert_held(&vmap_purge_lock);
    
    	valist = llist_del_all(&vmap_purge_list);
    	llist_for_each_entry(va, valist, purge_list) {
    		if (va->va_start < start)
    			start = va->va_start;
    		if (va->va_end > end)
    			end = va->va_end;
    		do_free = true;
    	}
    
    	if (!do_free)
    		return false;
    
    	flush_tlb_kernel_range(start, end);
    
    	spin_lock(&vmap_area_lock);
    	llist_for_each_entry_safe(va, n_va, valist, purge_list) {
    		int nr = (va->va_end - va->va_start) >> PAGE_SHIFT;
    
    		__free_vmap_area(va);
    		atomic_sub(nr, &vmap_lazy_nr);
    		cond_resched_lock(&vmap_area_lock);
    	}
    	spin_unlock(&vmap_area_lock);
    	return true;
    }
    
    /*
     * Kick off a purge of the outstanding lazy areas. Don't bother if somebody
     * is already purging.
     */
    static void try_purge_vmap_area_lazy(void)
    {
    	if (mutex_trylock(&vmap_purge_lock)) {
    		__purge_vmap_area_lazy(ULONG_MAX, 0);
    		mutex_unlock(&vmap_purge_lock);
    	}
    }
    
    /*
     * Kick off a purge of the outstanding lazy areas.
     */
    static void purge_vmap_area_lazy(void)
    {
    	mutex_lock(&vmap_purge_lock);
    	purge_fragmented_blocks_allcpus();
    	__purge_vmap_area_lazy(ULONG_MAX, 0);
    	mutex_unlock(&vmap_purge_lock);
    }
    
    /*
     * Free a vmap area, caller ensuring that the area has been unmapped
     * and flush_cache_vunmap had been called for the correct range
     * previously.
     */
    static void free_vmap_area_noflush(struct vmap_area *va)
    {
    	int nr_lazy;
    
    	nr_lazy = atomic_add_return((va->va_end - va->va_start) >> PAGE_SHIFT,
    				    &vmap_lazy_nr);
    
    	/* After this point, we may free va at any time */
    	llist_add(&va->purge_list, &vmap_purge_list);
    
    	if (unlikely(nr_lazy > lazy_max_pages()))
    		try_purge_vmap_area_lazy();
    }
    
    /*
     * Free and unmap a vmap area
     */
    static void free_unmap_vmap_area(struct vmap_area *va)
    {
    	flush_cache_vunmap(va->va_start, va->va_end);
    	unmap_vmap_area(va);
    	if (debug_pagealloc_enabled())
    		flush_tlb_kernel_range(va->va_start, va->va_end);
    
    	free_vmap_area_noflush(va);
    }
    
    static struct vmap_area *find_vmap_area(unsigned long addr)
    {
    	struct vmap_area *va;
    
    	spin_lock(&vmap_area_lock);
    	va = __find_vmap_area(addr);
    	spin_unlock(&vmap_area_lock);
    
    	return va;
    }
    
    /*** Per cpu kva allocator ***/
    
    /*
     * vmap space is limited especially on 32 bit architectures. Ensure there is
     * room for at least 16 percpu vmap blocks per CPU.
     */
    /*
     * If we had a constant VMALLOC_START and VMALLOC_END, we'd like to be able
     * to #define VMALLOC_SPACE		(VMALLOC_END-VMALLOC_START). Guess
     * instead (we just need a rough idea)
     */
    #if BITS_PER_LONG == 32
    #define VMALLOC_SPACE		(128UL*1024*1024)
    #else
    #define VMALLOC_SPACE		(128UL*1024*1024*1024)
    #endif
    
    #define VMALLOC_PAGES		(VMALLOC_SPACE / PAGE_SIZE)
    #define VMAP_MAX_ALLOC		BITS_PER_LONG	/* 256K with 4K pages */
    #define VMAP_BBMAP_BITS_MAX	1024	/* 4MB with 4K pages */
    #define VMAP_BBMAP_BITS_MIN	(VMAP_MAX_ALLOC*2)
    #define VMAP_MIN(x, y)		((x) < (y) ? (x) : (y)) /* can't use min() */
    #define VMAP_MAX(x, y)		((x) > (y) ? (x) : (y)) /* can't use max() */
    #define VMAP_BBMAP_BITS		\
    		VMAP_MIN(VMAP_BBMAP_BITS_MAX,	\
    		VMAP_MAX(VMAP_BBMAP_BITS_MIN,	\
    			VMALLOC_PAGES / roundup_pow_of_two(NR_CPUS) / 16))
    
    #define VMAP_BLOCK_SIZE		(VMAP_BBMAP_BITS * PAGE_SIZE)
    
    struct vmap_block_queue {
    	spinlock_t lock;
    	struct list_head free;
    };
    
    struct vmap_block {
    	spinlock_t lock;
    	struct vmap_area *va;
    	unsigned long free, dirty;
    	unsigned long dirty_min, dirty_max; /*< dirty range */
    	struct list_head free_list;
    	struct rcu_head rcu_head;
    	struct list_head purge;
    };
    
    /* Queue of free and dirty vmap blocks, for allocation and flushing purposes */
    static DEFINE_PER_CPU(struct vmap_block_queue, vmap_block_queue);
    
    /*
     * Radix tree of vmap blocks, indexed by address, to quickly find a vmap block
     * in the free path. Could get rid of this if we change the API to return a
     * "cookie" from alloc, to be passed to free. But no big deal yet.
     */
    static DEFINE_SPINLOCK(vmap_block_tree_lock);
    static RADIX_TREE(vmap_block_tree, GFP_ATOMIC);
    
    /*
     * We should probably have a fallback mechanism to allocate virtual memory
     * out of partially filled vmap blocks. However vmap block sizing should be
     * fairly reasonable according to the vmalloc size, so it shouldn't be a
     * big problem.
     */
    
    static unsigned long addr_to_vb_idx(unsigned long addr)
    {
    	addr -= VMALLOC_START & ~(VMAP_BLOCK_SIZE-1);
    	addr /= VMAP_BLOCK_SIZE;
    	return addr;
    }
    
    static void *vmap_block_vaddr(unsigned long va_start, unsigned long pages_off)
    {
    	unsigned long addr;
    
    	addr = va_start + (pages_off << PAGE_SHIFT);
    	BUG_ON(addr_to_vb_idx(addr) != addr_to_vb_idx(va_start));
    	return (void *)addr;
    }
    
    /**
     * new_vmap_block - allocates new vmap_block and occupies 2^order pages in this
     *                  block. Of course pages number can't exceed VMAP_BBMAP_BITS
     * @order:    how many 2^order pages should be occupied in newly allocated block
     * @gfp_mask: flags for the page level allocator
     *
     * Returns: virtual address in a newly allocated block or ERR_PTR(-errno)
     */
    static void *new_vmap_block(unsigned int order, gfp_t gfp_mask)
    {
    	struct vmap_block_queue *vbq;
    	struct vmap_block *vb;
    	struct vmap_area *va;
    	unsigned long vb_idx;
    	int node, err;
    	void *vaddr;
    
    	node = numa_node_id();
    
    	vb = kmalloc_node(sizeof(struct vmap_block),
    			gfp_mask & GFP_RECLAIM_MASK, node);
    	if (unlikely(!vb))
    		return ERR_PTR(-ENOMEM);
    
    	va = alloc_vmap_area(VMAP_BLOCK_SIZE, VMAP_BLOCK_SIZE,
    					VMALLOC_START, VMALLOC_END,
    					node, gfp_mask);
    	if (IS_ERR(va)) {
    		kfree(vb);
    		return ERR_CAST(va);
    	}
    
    	err = radix_tree_preload(gfp_mask);
    	if (unlikely(err)) {
    		kfree(vb);
    		free_vmap_area(va);
    		return ERR_PTR(err);
    	}
    
    	vaddr = vmap_block_vaddr(va->va_start, 0);
    	spin_lock_init(&vb->lock);
    	vb->va = va;
    	/* At least something should be left free */
    	BUG_ON(VMAP_BBMAP_BITS <= (1UL << order));
    	vb->free = VMAP_BBMAP_BITS - (1UL << order);
    	vb->dirty = 0;
    	vb->dirty_min = VMAP_BBMAP_BITS;
    	vb->dirty_max = 0;
    	INIT_LIST_HEAD(&vb->free_list);
    
    	vb_idx = addr_to_vb_idx(va->va_start);
    	spin_lock(&vmap_block_tree_lock);
    	err = radix_tree_insert(&vmap_block_tree, vb_idx, vb);
    	spin_unlock(&vmap_block_tree_lock);
    	BUG_ON(err);
    	radix_tree_preload_end();
    
    	vbq = &get_cpu_var(vmap_block_queue);
    	spin_lock(&vbq->lock);
    	list_add_tail_rcu(&vb->free_list, &vbq->free);
    	spin_unlock(&vbq->lock);
    	put_cpu_var(vmap_block_queue);
    
    	return vaddr;
    }
    
    static void free_vmap_block(struct vmap_block *vb)
    {
    	struct vmap_block *tmp;
    	unsigned long vb_idx;
    
    	vb_idx = addr_to_vb_idx(vb->va->va_start);
    	spin_lock(&vmap_block_tree_lock);
    	tmp = radix_tree_delete(&vmap_block_tree, vb_idx);
    	spin_unlock(&vmap_block_tree_lock);
    	BUG_ON(tmp != vb);
    
    	free_vmap_area_noflush(vb->va);
    	kfree_rcu(vb, rcu_head);
    }
    
    static void purge_fragmented_blocks(int cpu)
    {
    	LIST_HEAD(purge);
    	struct vmap_block *vb;
    	struct vmap_block *n_vb;
    	struct vmap_block_queue *vbq = &per_cpu(vmap_block_queue, cpu);
    
    	rcu_read_lock();
    	list_for_each_entry_rcu(vb, &vbq->free, free_list) {
    
    		if (!(vb->free + vb->dirty == VMAP_BBMAP_BITS && vb->dirty != VMAP_BBMAP_BITS))
    			continue;
    
    		spin_lock(&vb->lock);
    		if (vb->free + vb->dirty == VMAP_BBMAP_BITS && vb->dirty != VMAP_BBMAP_BITS) {
    			vb->free = 0; /* prevent further allocs after releasing lock */
    			vb->dirty = VMAP_BBMAP_BITS; /* prevent purging it again */
    			vb->dirty_min = 0;
    			vb->dirty_max = VMAP_BBMAP_BITS;
    			spin_lock(&vbq->lock);
    			list_del_rcu(&vb->free_list);
    			spin_unlock(&vbq->lock);
    			spin_unlock(&vb->lock);
    			list_add_tail(&vb->purge, &purge);
    		} else
    			spin_unlock(&vb->lock);
    	}
    	rcu_read_unlock();
    
    	list_for_each_entry_safe(vb, n_vb, &purge, purge) {
    		list_del(&vb->purge);
    		free_vmap_block(vb);
    	}
    }
    
    static void purge_fragmented_blocks_allcpus(void)
    {
    	int cpu;
    
    	for_each_possible_cpu(cpu)
    		purge_fragmented_blocks(cpu);
    }
    
    static void *vb_alloc(unsigned long size, gfp_t gfp_mask)
    {
    	struct vmap_block_queue *vbq;
    	struct vmap_block *vb;
    	void *vaddr = NULL;
    	unsigned int order;
    
    	BUG_ON(offset_in_page(size));
    	BUG_ON(size > PAGE_SIZE*VMAP_MAX_ALLOC);
    	if (WARN_ON(size == 0)) {
    		/*
    		 * Allocating 0 bytes isn't what caller wants since
    		 * get_order(0) returns funny result. Just warn and terminate
    		 * early.
    		 */
    		return NULL;
    	}
    	order = get_order(size);
    
    	rcu_read_lock();
    	vbq = &get_cpu_var(vmap_block_queue);
    	list_for_each_entry_rcu(vb, &vbq->free, free_list) {
    		unsigned long pages_off;
    
    		spin_lock(&vb->lock);
    		if (vb->free < (1UL << order)) {
    			spin_unlock(&vb->lock);
    			continue;
    		}
    
    		pages_off = VMAP_BBMAP_BITS - vb->free;
    		vaddr = vmap_block_vaddr(vb->va->va_start, pages_off);
    		vb->free -= 1UL << order;
    		if (vb->free == 0) {
    			spin_lock(&vbq->lock);
    			list_del_rcu(&vb->free_list);
    			spin_unlock(&vbq->lock);
    		}
    
    		spin_unlock(&vb->lock);
    		break;
    	}
    
    	put_cpu_var(vmap_block_queue);
    	rcu_read_unlock();
    
    	/* Allocate new block if nothing was found */
    	if (!vaddr)
    		vaddr = new_vmap_block(order, gfp_mask);
    
    	return vaddr;
    }
    
    static void vb_free(unsigned long addr, unsigned long size)
    {
    	unsigned long offset;
    	unsigned long vb_idx;
    	unsigned int order;
    	struct vmap_block *vb;
    
    	BUG_ON(offset_in_page(size));
    	BUG_ON(size > PAGE_SIZE*VMAP_MAX_ALLOC);
    
    	flush_cache_vunmap(addr, addr + size);
    
    	order = get_order(size);
    
    	offset = (addr & (VMAP_BLOCK_SIZE - 1)) >> PAGE_SHIFT;
    
    	vb_idx = addr_to_vb_idx(addr);
    	rcu_read_lock();
    	vb = radix_tree_lookup(&vmap_block_tree, vb_idx);
    	rcu_read_unlock();
    	BUG_ON(!vb);
    
    	unmap_kernel_range_noflush(addr, size);
    
    	if (debug_pagealloc_enabled())
    		flush_tlb_kernel_range(addr, addr + size);
    
    	spin_lock(&vb->lock);
    
    	/* Expand dirty range */
    	vb->dirty_min = min(vb->dirty_min, offset);
    	vb->dirty_max = max(vb->dirty_max, offset + (1UL << order));
    
    	vb->dirty += 1UL << order;
    	if (vb->dirty == VMAP_BBMAP_BITS) {
    		BUG_ON(vb->free);
    		spin_unlock(&vb->lock);
    		free_vmap_block(vb);
    	} else
    		spin_unlock(&vb->lock);
    }
    
    /**
     * vm_unmap_aliases - unmap outstanding lazy aliases in the vmap layer
     *
     * The vmap/vmalloc layer lazily flushes kernel virtual mappings primarily
     * to amortize TLB flushing overheads. What this means is that any page you
     * have now, may, in a former life, have been mapped into kernel virtual
     * address by the vmap layer and so there might be some CPUs with TLB entries
     * still referencing that page (additional to the regular 1:1 kernel mapping).
     *
     * vm_unmap_aliases flushes all such lazy mappings. After it returns, we can
     * be sure that none of the pages we have control over will have any aliases
     * from the vmap layer.
     */
    void vm_unmap_aliases(void)
    {
    	unsigned long start = ULONG_MAX, end = 0;
    	int cpu;
    	int flush = 0;
    
    	if (unlikely(!vmap_initialized))
    		return;
    
    	might_sleep();
    
    	for_each_possible_cpu(cpu) {
    		struct vmap_block_queue *vbq = &per_cpu(vmap_block_queue, cpu);
    		struct vmap_block *vb;
    
    		rcu_read_lock();
    		list_for_each_entry_rcu(vb, &vbq->free, free_list) {
    			spin_lock(&vb->lock);
    			if (vb->dirty && vb->dirty != VMAP_BBMAP_BITS) {
    				unsigned long va_start = vb->va->va_start;
    				unsigned long s, e;
    
    				s = va_start + (vb->dirty_min << PAGE_SHIFT);
    				e = va_start + (vb->dirty_max << PAGE_SHIFT);
    
    				start = min(s, start);
    				end   = max(e, end);
    
    				flush = 1;
    			}
    			spin_unlock(&vb->lock);
    		}
    		rcu_read_unlock();
    	}
    
    	mutex_lock(&vmap_purge_lock);
    	purge_fragmented_blocks_allcpus();
    	if (!__purge_vmap_area_lazy(start, end) && flush)
    		flush_tlb_kernel_range(start, end);
    	mutex_unlock(&vmap_purge_lock);
    }
    EXPORT_SYMBOL_GPL(vm_unmap_aliases);
    
    /**
     * vm_unmap_ram - unmap linear kernel address space set up by vm_map_ram
     * @mem: the pointer returned by vm_map_ram
     * @count: the count passed to that vm_map_ram call (cannot unmap partial)
     */
    void vm_unmap_ram(const void *mem, unsigned int count)
    {
    	unsigned long size = (unsigned long)count << PAGE_SHIFT;
    	unsigned long addr = (unsigned long)mem;
    	struct vmap_area *va;
    
    	might_sleep();
    	BUG_ON(!addr);
    	BUG_ON(addr < VMALLOC_START);
    	BUG_ON(addr > VMALLOC_END);
    	BUG_ON(!PAGE_ALIGNED(addr));
    
    	if (likely(count <= VMAP_MAX_ALLOC)) {
    		debug_check_no_locks_freed(mem, size);
    		vb_free(addr, size);
    		return;
    	}
    
    	va = find_vmap_area(addr);
    	BUG_ON(!va);
    	debug_check_no_locks_freed((void *)va->va_start,
    				    (va->va_end - va->va_start));
    	free_unmap_vmap_area(va);
    }
    EXPORT_SYMBOL(vm_unmap_ram);
    
    /**
     * vm_map_ram - map pages linearly into kernel virtual address (vmalloc space)
     * @pages: an array of pointers to the pages to be mapped
     * @count: number of pages
     * @node: prefer to allocate data structures on this node
     * @prot: memory protection to use. PAGE_KERNEL for regular RAM
     *
     * If you use this function for less than VMAP_MAX_ALLOC pages, it could be
     * faster than vmap so it's good.  But if you mix long-life and short-life
     * objects with vm_map_ram(), it could consume lots of address space through
     * fragmentation (especially on a 32bit machine).  You could see failures in
     * the end.  Please use this function for short-lived objects.
     *
     * Returns: a pointer to the address that has been mapped, or %NULL on failure
     */
    void *vm_map_ram(struct page **pages, unsigned int count, int node, pgprot_t prot)
    {
    	unsigned long size = (unsigned long)count << PAGE_SHIFT;
    	unsigned long addr;
    	void *mem;
    
    	if (likely(count <= VMAP_MAX_ALLOC)) {
    		mem = vb_alloc(size, GFP_KERNEL);
    		if (IS_ERR(mem))
    			return NULL;
    		addr = (unsigned long)mem;
    	} else {
    		struct vmap_area *va;
    		va = alloc_vmap_area(size, PAGE_SIZE,
    				VMALLOC_START, VMALLOC_END, node, GFP_KERNEL);
    		if (IS_ERR(va))
    			return NULL;
    
    		addr = va->va_start;
    		mem = (void *)addr;
    	}
    	if (map_kernel_range(addr, size, prot, pages) < 0) {
    		vm_unmap_ram(mem, count);
    		return NULL;
    	}
    	return mem;
    }
    EXPORT_SYMBOL(vm_map_ram);
    
    static struct vm_struct *vmlist __initdata;
    /**
     * vm_area_add_early - add vmap area early during boot
     * @vm: vm_struct to add
     *
     * This function is used to add fixed kernel vm area to vmlist before
     * vmalloc_init() is called.  @vm->addr, @vm->size, and @vm->flags
     * should contain proper values and the other fields should be zero.
     *
     * DO NOT USE THIS FUNCTION UNLESS YOU KNOW WHAT YOU'RE DOING.
     */
    void __init vm_area_add_early(struct vm_struct *vm)
    {
    	struct vm_struct *tmp, **p;
    
    	BUG_ON(vmap_initialized);
    	for (p = &vmlist; (tmp = *p) != NULL; p = &tmp->next) {
    		if (tmp->addr >= vm->addr) {
    			BUG_ON(tmp->addr < vm->addr + vm->size);
    			break;
    		} else
    			BUG_ON(tmp->addr + tmp->size > vm->addr);
    	}
    	vm->next = *p;
    	*p = vm;
    }
    
    /**
     * vm_area_register_early - register vmap area early during boot
     * @vm: vm_struct to register
     * @align: requested alignment
     *
     * This function is used to register kernel vm area before
     * vmalloc_init() is called.  @vm->size and @vm->flags should contain
     * proper values on entry and other fields should be zero.  On return,
     * vm->addr contains the allocated address.
     *
     * DO NOT USE THIS FUNCTION UNLESS YOU KNOW WHAT YOU'RE DOING.
     */
    void __init vm_area_register_early(struct vm_struct *vm, size_t align)
    {
    	static size_t vm_init_off __initdata;
    	unsigned long addr;
    
    	addr = ALIGN(VMALLOC_START + vm_init_off, align);
    	vm_init_off = PFN_ALIGN(addr + vm->size) - VMALLOC_START;
    
    	vm->addr = (void *)addr;
    
    	vm_area_add_early(vm);
    }
    
    static void vmap_init_free_space(void)
    {
    	unsigned long vmap_start = 1;
    	const unsigned long vmap_end = ULONG_MAX;
    	struct vmap_area *busy, *free;
    
    	/*
    	 *     B     F     B     B     B     F
    	 * -|-----|.....|-----|-----|-----|.....|-
    	 *  |           The KVA space           |
    	 *  |<--------------------------------->|
    	 */
    	list_for_each_entry(busy, &vmap_area_list, list) {
    		if (busy->va_start - vmap_start > 0) {
    			free = kmem_cache_zalloc(vmap_area_cachep, GFP_NOWAIT);
    			if (!WARN_ON_ONCE(!free)) {
    				free->va_start = vmap_start;
    				free->va_end = busy->va_start;
    
    				insert_vmap_area_augment(free, NULL,
    					&free_vmap_area_root,
    						&free_vmap_area_list);
    			}
    		}
    
    		vmap_start = busy->va_end;
    	}
    
    	if (vmap_end - vmap_start > 0) {
    		free = kmem_cache_zalloc(vmap_area_cachep, GFP_NOWAIT);
    		if (!WARN_ON_ONCE(!free)) {
    			free->va_start = vmap_start;
    			free->va_end = vmap_end;
    
    			insert_vmap_area_augment(free, NULL,
    				&free_vmap_area_root,
    					&free_vmap_area_list);
    		}
    	}
    }
    
    void __init vmalloc_init(void)
    {
    	struct vmap_area *va;
    	struct vm_struct *tmp;
    	int i;
    
    	/*
    	 * Create the cache for vmap_area objects.
    	 */
    	vmap_area_cachep = KMEM_CACHE(vmap_area, SLAB_PANIC);
    
    	for_each_possible_cpu(i) {
    		struct vmap_block_queue *vbq;
    		struct vfree_deferred *p;
    
    		vbq = &per_cpu(vmap_block_queue, i);
    		spin_lock_init(&vbq->lock);
    		INIT_LIST_HEAD(&vbq->free);
    		p = &per_cpu(vfree_deferred, i);
    		init_llist_head(&p->list);
    		INIT_WORK(&p->wq, free_work);
    	}
    
    	/* Import existing vmlist entries. */
    	for (tmp = vmlist; tmp; tmp = tmp->next) {
    		va = kmem_cache_zalloc(vmap_area_cachep, GFP_NOWAIT);
    		if (WARN_ON_ONCE(!va))
    			continue;
    
    		va->flags = VM_VM_AREA;
    		va->va_start = (unsigned long)tmp->addr;
    		va->va_end = va->va_start + tmp->size;
    		va->vm = tmp;
    		insert_vmap_area(va, &vmap_area_root, &vmap_area_list);
    	}
    
    	/*
    	 * Now we can initialize a free vmap space.
    	 */
    	vmap_init_free_space();
    	vmap_initialized = true;
    }
    
    /**
     * unmap_kernel_range - unmap kernel VM area and flush cache and TLB
     * @addr: start of the VM area to unmap
     * @size: size of the VM area to unmap
     *
     * Similar to unmap_kernel_range_noflush() but flushes vcache before
     * the unmapping and tlb after.
     */
    void unmap_kernel_range(unsigned long addr, unsigned long size)
    {
    	unsigned long end = addr + size;
    
    	flush_cache_vunmap(addr, end);
    	unmap_kernel_range_noflush(addr, size);
    	flush_tlb_kernel_range(addr, end);
    }
    
    int map_vm_area(struct vm_struct *area, pgprot_t prot, struct page **pages)
    {
    	unsigned long addr = (unsigned long)area->addr;
    	int err;
    
    	err = map_kernel_range(addr, get_vm_area_size(area), prot, pages);
    
    	return err > 0 ? 0 : err;
    }
    EXPORT_SYMBOL_GPL(map_vm_area);
    
    static void setup_vmalloc_vm(struct vm_struct *vm, struct vmap_area *va,
    			      unsigned long flags, const void *caller)
    {
    	spin_lock(&vmap_area_lock);
    	vm->flags = flags;
    	vm->addr = (void *)va->va_start;
    	vm->size = va->va_end - va->va_start;
    	vm->caller = caller;
    	va->vm = vm;
    	va->flags |= VM_VM_AREA;
    	spin_unlock(&vmap_area_lock);
    }
    
    static void clear_vm_uninitialized_flag(struct vm_struct *vm)
    {
    	/*
    	 * Before removing VM_UNINITIALIZED,
    	 * we should make sure that vm has proper values.
    	 * Pair with smp_rmb() in show_numa_info().
    	 */
    	smp_wmb();
    	vm->flags &= ~VM_UNINITIALIZED;
    }
    
    static struct vm_struct *__get_vm_area_node(unsigned long size,
    		unsigned long align, unsigned long flags, unsigned long start,
    		unsigned long end, int node, gfp_t gfp_mask, const void *caller)
    {
    	struct vmap_area *va;
    	struct vm_struct *area;
    
    	BUG_ON(in_interrupt());
    	size = PAGE_ALIGN(size);
    	if (unlikely(!size))
    		return NULL;
    
    	if (flags & VM_IOREMAP)
    		align = 1ul << clamp_t(int, get_count_order_long(size),
    				       PAGE_SHIFT, IOREMAP_MAX_ORDER);
    
    	area = kzalloc_node(sizeof(*area), gfp_mask & GFP_RECLAIM_MASK, node);
    	if (unlikely(!area))
    		return NULL;
    
    	if (!(flags & VM_NO_GUARD))
    		size += PAGE_SIZE;
    
    	va = alloc_vmap_area(size, align, start, end, node, gfp_mask);
    	if (IS_ERR(va)) {
    		kfree(area);
    		return NULL;
    	}
    
    	setup_vmalloc_vm(area, va, flags, caller);
    
    	return area;
    }
    
    struct vm_struct *__get_vm_area(unsigned long size, unsigned long flags,
    						unsigned long start, unsigned long end)
    {
    	return __get_vm_area_node(size, 1, flags, start, end, NUMA_NO_NODE,
    				  GFP_KERNEL, __builtin_return_address(0));
    }
    EXPORT_SYMBOL_GPL(__get_vm_area);
    
    struct vm_struct *__get_vm_area_caller(unsigned long size, unsigned long flags,
    				       unsigned long start, unsigned long end,
    				       const void *caller)
    {
    	return __get_vm_area_node(size, 1, flags, start, end, NUMA_NO_NODE,
    				  GFP_KERNEL, caller);
    }
    
    /**
     *	get_vm_area  -  reserve a contiguous kernel virtual area
     *	@size:		size of the area
     *	@flags:		%VM_IOREMAP for I/O mappings or VM_ALLOC
     *
     *	Search an area of @size in the kernel virtual mapping area,
     *	and reserved it for out purposes.  Returns the area descriptor
     *	on success or %NULL on failure.
     */
    struct vm_struct *get_vm_area(unsigned long size, unsigned long flags)
    {
    	return __get_vm_area_node(size, 1, flags, VMALLOC_START, VMALLOC_END,
    				  NUMA_NO_NODE, GFP_KERNEL,
    				  __builtin_return_address(0));
    }
    
    struct vm_struct *get_vm_area_caller(unsigned long size, unsigned long flags,
    				const void *caller)
    {
    	unsigned long align = 1;
    
    	if (sp_check_vm_huge_page(flags))
    		align = PMD_SIZE;
    
    	return __get_vm_area_node(size, align, flags, VMALLOC_START, VMALLOC_END,
    				  NUMA_NO_NODE, GFP_KERNEL, caller);
    }
    
    /**
     *	find_vm_area  -  find a continuous kernel virtual area
     *	@addr:		base address
     *
     *	Search for the kernel VM area starting at @addr, and return it.
     *	It is up to the caller to do all required locking to keep the returned
     *	pointer valid.
     */
    struct vm_struct *find_vm_area(const void *addr)
    {
    	struct vmap_area *va;
    
    	va = find_vmap_area((unsigned long)addr);
    	if (va && va->flags & VM_VM_AREA)
    		return va->vm;
    
    	return NULL;
    }
    
    /**
     *	remove_vm_area  -  find and remove a continuous kernel virtual area
     *	@addr:		base address
     *
     *	Search for the kernel VM area starting at @addr, and remove it.
     *	This function returns the found VM area, but using it is NOT safe
     *	on SMP machines, except for its size or flags.
     */
    struct vm_struct *remove_vm_area(const void *addr)
    {
    	struct vmap_area *va;
    
    	might_sleep();
    
    	va = find_vmap_area((unsigned long)addr);
    	if (va && va->flags & VM_VM_AREA) {
    		struct vm_struct *vm = va->vm;
    
    		spin_lock(&vmap_area_lock);
    		va->vm = NULL;
    		va->flags &= ~VM_VM_AREA;
    		va->flags |= VM_LAZY_FREE;
    		spin_unlock(&vmap_area_lock);
    
    		kasan_free_shadow(vm);
    		free_unmap_vmap_area(va);
    
    		return vm;
    	}
    	return NULL;
    }
    
    static void __vunmap(const void *addr, int deallocate_pages)
    {
    	struct vm_struct *area;
    	unsigned int page_order = 0;
    
    	if (!addr)
    		return;
    
    	if (WARN(!PAGE_ALIGNED(addr), "Trying to vfree() bad address (%p)\n",
    			addr))
    		return;
    
    	area = find_vm_area(addr);
    	if (unlikely(!area)) {
    		WARN(1, KERN_ERR "Trying to vfree() nonexistent vm area (%p)\n",
    				addr);
    		return;
    	}
    
    	/* unmap a sharepool vm area will cause meamleak! */
    	if (is_vmalloc_sharepool(area->flags)) {
    		WARN(1, KERN_ERR "Memory leak due to vfree() sharepool vm area (%p) !\n", addr);
    		return;
    	}
    
    	if (is_vmalloc_huge(area->flags))
    		page_order = PMD_SHIFT - PAGE_SHIFT;
    
    	debug_check_no_locks_freed(area->addr, get_vm_area_size(area));
    	debug_check_no_obj_freed(area->addr, get_vm_area_size(area));
    
    	remove_vm_area(addr);
    	if (deallocate_pages) {
    		int i;
    
    		for (i = 0; i < area->nr_pages; i += 1U << page_order) {
    			struct page *page = area->pages[i];
    
    			BUG_ON(!page);
    			if (sp_is_enabled())
    				sp_free_pages(page, area);
    			else
    				__free_pages(page, page_order);
    		}
    
    		kvfree(area->pages);
    	}
    
    	kfree(area);
    	return;
    }
    
    static inline void __vfree_deferred(const void *addr)
    {
    	/*
    	 * Use raw_cpu_ptr() because this can be called from preemptible
    	 * context. Preemption is absolutely fine here, because the llist_add()
    	 * implementation is lockless, so it works even if we are adding to
    	 * nother cpu's list.  schedule_work() should be fine with this too.
    	 */
    	struct vfree_deferred *p = raw_cpu_ptr(&vfree_deferred);
    
    	if (llist_add((struct llist_node *)addr, &p->list))
    		schedule_work(&p->wq);
    }
    
    /**
     *	vfree_atomic  -  release memory allocated by vmalloc()
     *	@addr:		memory base address
     *
     *	This one is just like vfree() but can be called in any atomic context
     *	except NMIs.
     */
    void vfree_atomic(const void *addr)
    {
    	BUG_ON(in_nmi());
    
    	kmemleak_free(addr);
    
    	if (!addr)
    		return;
    	__vfree_deferred(addr);
    }
    
    /**
     *	vfree  -  release memory allocated by vmalloc()
     *	@addr:		memory base address
     *
     *	Free the virtually continuous memory area starting at @addr, as
     *	obtained from vmalloc(), vmalloc_32() or __vmalloc(). If @addr is
     *	NULL, no operation is performed.
     *
     *	Must not be called in NMI context (strictly speaking, only if we don't
     *	have CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG, but making the calling
     *	conventions for vfree() arch-depenedent would be a really bad idea)
     *
     *	NOTE: assumes that the object at @addr has a size >= sizeof(llist_node)
     */
    void vfree(const void *addr)
    {
    	BUG_ON(in_nmi());
    
    	kmemleak_free(addr);
    
    	if (!addr)
    		return;
    	if (unlikely(in_interrupt()))
    		__vfree_deferred(addr);
    	else
    		__vunmap(addr, 1);
    }
    EXPORT_SYMBOL(vfree);
    
    /**
     *	vunmap  -  release virtual mapping obtained by vmap()
     *	@addr:		memory base address
     *
     *	Free the virtually contiguous memory area starting at @addr,
     *	which was created from the page array passed to vmap().
     *
     *	Must not be called in interrupt context.
     */
    void vunmap(const void *addr)
    {
    	BUG_ON(in_interrupt());
    	might_sleep();
    	if (addr)
    		__vunmap(addr, 0);
    }
    EXPORT_SYMBOL(vunmap);
    
    /**
     *	vmap  -  map an array of pages into virtually contiguous space
     *	@pages:		array of page pointers
     *	@count:		number of pages to map
     *	@flags:		vm_area->flags
     *	@prot:		page protection for the mapping
     *
     *	Maps @count pages from @pages into contiguous kernel virtual
     *	space.
     */
    void *vmap(struct page **pages, unsigned int count,
    		unsigned long flags, pgprot_t prot)
    {
    	struct vm_struct *area;
    	unsigned long size;		/* In bytes */
    
    	might_sleep();
    
    	if (count > totalram_pages)
    		return NULL;
    
    	size = (unsigned long)count << PAGE_SHIFT;
    	area = get_vm_area_caller(size, flags, __builtin_return_address(0));
    	if (!area)
    		return NULL;
    
    	if (map_kernel_range((unsigned long)area->addr, size, prot,
    			pages) < 0) {
    		vunmap(area->addr);
    		return NULL;
    	}
    
    	return area->addr;
    }
    EXPORT_SYMBOL(vmap);
    
    /**
     *	vmap_hugepag  -  map an array of huge pages into virtually contiguous space
     *	@pages:		array of huge page pointers
     *	@count:		number of pages to map
     *	@flags:		vm_area->flags
     *	@prot:		page protection for the mapping
     *
     *	Maps @count pages from @pages into contiguous kernel virtual
     *	space.
     */
    void *vmap_hugepage(struct page **pages, unsigned int count,
    		    unsigned long flags, pgprot_t prot)
    {
    	struct vm_struct *area;
    	unsigned long size;		/* In bytes */
    
    	might_sleep();
    
    	if (count > totalram_pages)
    		return NULL;
    
    	size = (unsigned long)count << PMD_SHIFT;
    	area = get_vm_area_caller(size, flags, __builtin_return_address(0));
    	if (!area)
    		return NULL;
    
    	if (vmap_hugepages_range((unsigned long)area->addr,
    				 (unsigned long)area->addr + size, prot,
    				 pages, PMD_SHIFT) < 0) {
    		vunmap(area->addr);
    		return NULL;
    	}
    
    	return area->addr;
    }
    EXPORT_SYMBOL(vmap_hugepage);
    
    static void *__vmalloc_node(unsigned long size, unsigned long align,
    			    gfp_t gfp_mask, pgprot_t prot,
    			    int node, const void *caller);
    static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
    				 pgprot_t prot, unsigned int page_shift, int node)
    {
    	struct page **pages;
    	unsigned long addr = (unsigned long)area->addr;
    	unsigned long size = get_vm_area_size(area);
    	unsigned int page_order = page_shift - PAGE_SHIFT;
    	unsigned int nr_pages;
    	unsigned long array_size;
    	unsigned int i;
    	const gfp_t nested_gfp = (gfp_mask & GFP_RECLAIM_MASK) | __GFP_ZERO;
    	const gfp_t alloc_mask = gfp_mask | __GFP_NOWARN;
    	const gfp_t highmem_mask = (gfp_mask & (GFP_DMA | GFP_DMA32)) ?
    					0 :
    					__GFP_HIGHMEM;
    
    	nr_pages = size >> PAGE_SHIFT;
    	array_size = (unsigned long)nr_pages * sizeof(struct page *);
    
    	/* Please note that the recursion is strictly bounded. */
    	if (array_size > PAGE_SIZE) {
    		pages = __vmalloc_node(array_size, 1, nested_gfp|highmem_mask,
    				PAGE_KERNEL, node, area->caller);
    	} else {
    		pages = kmalloc_node(array_size, nested_gfp, node);
    	}
    
    	if (!pages) {
    		remove_vm_area(area->addr);
    		kfree(area);
    		return NULL;
    	}
    
    	area->pages = pages;
    	area->nr_pages = nr_pages;
    
    	for (i = 0; i < area->nr_pages; i += 1U << page_order) {
    		struct page *page;
    		int p;
    
    		if (sp_is_enabled())
    			page = sp_alloc_pages(area, alloc_mask|highmem_mask,
    					      page_order, node);
    		else
    			page = alloc_pages_node(node, alloc_mask|highmem_mask,
    						page_order);
    		if (unlikely(!page)) {
    			/* Successfully allocated i pages, free them in __vunmap() */
    			area->nr_pages = i;
    			goto fail;
    		}
    
    		for (p = 0; p < (1U << page_order); p++)
    			area->pages[i + p] = page + p;
    
    		if (gfpflags_allow_blocking(gfp_mask|highmem_mask))
    			cond_resched();
    	}
    
    	if (vmap_pages_range(addr, addr + size, prot, pages, page_shift) < 0)
    		goto fail;
    
    	return area->addr;
    
    fail:
    	warn_alloc(gfp_mask, NULL,
    			  "vmalloc: allocation failure, allocated %ld of %ld bytes",
    			  (area->nr_pages*PAGE_SIZE), size);
    	vfree(area->addr);
    	return NULL;
    }
    
    /**
     *	__vmalloc_node_range  -  allocate virtually contiguous memory
     *	@size:		allocation size
     *	@align:		desired alignment
     *	@start:		vm area range start
     *	@end:		vm area range end
     *	@gfp_mask:	flags for the page level allocator
     *	@prot:		protection mask for the allocated pages
     *	@vm_flags:	additional vm area flags (e.g. %VM_NO_GUARD)
     *	@node:		node to use for allocation or NUMA_NO_NODE
     *	@caller:	caller's return address
     *
     *	Allocate enough pages to cover @size from the page level
     *	allocator with @gfp_mask flags.  Map them into contiguous
     *	kernel virtual space, using a pagetable protection of @prot.
     */
    void *__vmalloc_node_range(unsigned long size, unsigned long align,
    			unsigned long start, unsigned long end, gfp_t gfp_mask,
    			pgprot_t prot, unsigned long vm_flags, int node,
    			const void *caller)
    {
    	struct vm_struct *area = NULL;
    	void *addr;
    	unsigned long real_size = size;
    	unsigned long real_align = align;
    	unsigned int shift = PAGE_SHIFT;
    
    	if (!size || (size >> PAGE_SHIFT) > totalram_pages)
    		goto fail;
    
    	if (vmap_allow_huge && (pgprot_val(prot) == pgprot_val(PAGE_KERNEL)) && is_vmalloc_huge(vm_flags)) {
    		/*
    		 * Alloc huge pages. Only valid for PAGE_KERNEL allocations and
    		 * VM_HUGE_PAGES flags.
    		 */
    
    		shift = PMD_SHIFT;
    		align = max(real_align, 1UL << shift);
    		size = ALIGN(real_size, 1UL << shift);
    	}
    
    	size = PAGE_ALIGN(size);
    	area = __get_vm_area_node(size, align, VM_ALLOC | VM_UNINITIALIZED |
    				vm_flags, start, end, node, gfp_mask, caller);
    	if (!area)
    		goto fail;
    
    	addr = __vmalloc_area_node(area, gfp_mask, prot, shift, node);
    	if (!addr)
    		goto fail;
    
    	/*
    	 * First make sure the mappings are removed from all page-tables
    	 * before they are freed.
    	 */
    	vmalloc_sync_unmappings();
    
    	/*
    	 * In this function, newly allocated vm_struct has VM_UNINITIALIZED
    	 * flag. It means that vm_struct is not fully initialized.
    	 * Now, it is fully initialized, so remove this flag here.
    	 */
    	clear_vm_uninitialized_flag(area);
    
    	kmemleak_vmalloc(area, size, gfp_mask);
    
    	return addr;
    
    fail:
    
    	if (!area) {
    		/* Warn for area allocation, page allocations already warn */
    		warn_alloc(gfp_mask, NULL,
    			  "vmalloc: allocation failure: %lu bytes", real_size);
    	}
    	return NULL;
    }
    
    /**
     *	__vmalloc_node  -  allocate virtually contiguous memory
     *	@size:		allocation size
     *	@align:		desired alignment
     *	@gfp_mask:	flags for the page level allocator
     *	@prot:		protection mask for the allocated pages
     *	@node:		node to use for allocation or NUMA_NO_NODE
     *	@caller:	caller's return address
     *
     *	Allocate enough pages to cover @size from the page level
     *	allocator with @gfp_mask flags.  Map them into contiguous
     *	kernel virtual space, using a pagetable protection of @prot.
     *
     *	Reclaim modifiers in @gfp_mask - __GFP_NORETRY, __GFP_RETRY_MAYFAIL
     *	and __GFP_NOFAIL are not supported
     *
     *	Any use of gfp flags outside of GFP_KERNEL should be consulted
     *	with mm people.
     *
     */
    static void *__vmalloc_node(unsigned long size, unsigned long align,
    			    gfp_t gfp_mask, pgprot_t prot,
    			    int node, const void *caller)
    {
    	return __vmalloc_node_range(size, align, VMALLOC_START, VMALLOC_END,
    				gfp_mask, prot, 0, node, caller);
    }
    
    void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)
    {
    	return __vmalloc_node(size, 1, gfp_mask, prot, NUMA_NO_NODE,
    				__builtin_return_address(0));
    }
    EXPORT_SYMBOL(__vmalloc);
    
    static inline void *__vmalloc_node_flags(unsigned long size,
    					int node, gfp_t flags)
    {
    	return __vmalloc_node(size, 1, flags, PAGE_KERNEL,
    					node, __builtin_return_address(0));
    }
    
    
    void *__vmalloc_node_flags_caller(unsigned long size, int node, gfp_t flags,
    				  void *caller)
    {
    	return __vmalloc_node(size, 1, flags, PAGE_KERNEL, node, caller);
    }
    
    /**
     *	vmalloc  -  allocate virtually contiguous memory
     *	@size:		allocation size
     *	Allocate enough pages to cover @size from the page level
     *	allocator and map them into contiguous kernel virtual space.
     *
     *	For tight control over page level allocator and protection flags
     *	use __vmalloc() instead.
     */
    void *vmalloc(unsigned long size)
    {
    	return __vmalloc_node_flags(size, NUMA_NO_NODE,
    				    GFP_KERNEL);
    }
    EXPORT_SYMBOL(vmalloc);
    
    /**
     *	vzalloc - allocate virtually contiguous memory with zero fill
     *	@size:	allocation size
     *	Allocate enough pages to cover @size from the page level
     *	allocator and map them into contiguous kernel virtual space.
     *	The memory allocated is set to zero.
     *
     *	For tight control over page level allocator and protection flags
     *	use __vmalloc() instead.
     */
    void *vzalloc(unsigned long size)
    {
    	return __vmalloc_node_flags(size, NUMA_NO_NODE,
    				GFP_KERNEL | __GFP_ZERO);
    }
    EXPORT_SYMBOL(vzalloc);
    
    /**
     * vmalloc_user - allocate zeroed virtually contiguous memory for userspace
     * @size: allocation size
     *
     * The resulting memory area is zeroed so it can be mapped to userspace
     * without leaking data.
     */
    void *vmalloc_user(unsigned long size)
    {
    	struct vm_struct *area;
    	void *ret;
    
    	ret = __vmalloc_node(size, SHMLBA,
    			     GFP_KERNEL | __GFP_ZERO,
    			     PAGE_KERNEL, NUMA_NO_NODE,
    			     __builtin_return_address(0));
    	if (ret) {
    		area = find_vm_area(ret);
    		area->flags |= VM_USERMAP;
    	}
    	return ret;
    }
    EXPORT_SYMBOL(vmalloc_user);
    
    /**
     *	vmalloc_node  -  allocate memory on a specific node
     *	@size:		allocation size
     *	@node:		numa node
     *
     *	Allocate enough pages to cover @size from the page level
     *	allocator and map them into contiguous kernel virtual space.
     *
     *	For tight control over page level allocator and protection flags
     *	use __vmalloc() instead.
     */
    void *vmalloc_node(unsigned long size, int node)
    {
    	return __vmalloc_node(size, 1, GFP_KERNEL, PAGE_KERNEL,
    					node, __builtin_return_address(0));
    }
    EXPORT_SYMBOL(vmalloc_node);
    
    /**
     * vzalloc_node - allocate memory on a specific node with zero fill
     * @size:	allocation size
     * @node:	numa node
     *
     * Allocate enough pages to cover @size from the page level
     * allocator and map them into contiguous kernel virtual space.
     * The memory allocated is set to zero.
     *
     * For tight control over page level allocator and protection flags
     * use __vmalloc_node() instead.
     */
    void *vzalloc_node(unsigned long size, int node)
    {
    	return __vmalloc_node_flags(size, node,
    			 GFP_KERNEL | __GFP_ZERO);
    }
    EXPORT_SYMBOL(vzalloc_node);
    
    /**
     *	vmalloc_exec  -  allocate virtually contiguous, executable memory
     *	@size:		allocation size
     *
     *	Kernel-internal function to allocate enough pages to cover @size
     *	the page level allocator and map them into contiguous and
     *	executable kernel virtual space.
     *
     *	For tight control over page level allocator and protection flags
     *	use __vmalloc() instead.
     */
    
    void *vmalloc_exec(unsigned long size)
    {
    	return __vmalloc_node(size, 1, GFP_KERNEL, PAGE_KERNEL_EXEC,
    			      NUMA_NO_NODE, __builtin_return_address(0));
    }
    
    #if defined(CONFIG_64BIT) && defined(CONFIG_ZONE_DMA32)
    #define GFP_VMALLOC32 (GFP_DMA32 | GFP_KERNEL)
    #elif defined(CONFIG_64BIT) && defined(CONFIG_ZONE_DMA)
    #define GFP_VMALLOC32 (GFP_DMA | GFP_KERNEL)
    #else
    /*
     * 64b systems should always have either DMA or DMA32 zones. For others
     * GFP_DMA32 should do the right thing and use the normal zone.
     */
    #define GFP_VMALLOC32 GFP_DMA32 | GFP_KERNEL
    #endif
    
    /**
     *	vmalloc_32  -  allocate virtually contiguous memory (32bit addressable)
     *	@size:		allocation size
     *
     *	Allocate enough 32bit PA addressable pages to cover @size from the
     *	page level allocator and map them into contiguous kernel virtual space.
     */
    void *vmalloc_32(unsigned long size)
    {
    	return __vmalloc_node(size, 1, GFP_VMALLOC32, PAGE_KERNEL,
    			      NUMA_NO_NODE, __builtin_return_address(0));
    }
    EXPORT_SYMBOL(vmalloc_32);
    
    /**
     * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory
     *	@size:		allocation size
     *
     * The resulting memory area is 32bit addressable and zeroed so it can be
     * mapped to userspace without leaking data.
     */
    void *vmalloc_32_user(unsigned long size)
    {
    	struct vm_struct *area;
    	void *ret;
    
    	ret = __vmalloc_node(size, 1, GFP_VMALLOC32 | __GFP_ZERO, PAGE_KERNEL,
    			     NUMA_NO_NODE, __builtin_return_address(0));
    	if (ret) {
    		area = find_vm_area(ret);
    		area->flags |= VM_USERMAP;
    	}
    	return ret;
    }
    EXPORT_SYMBOL(vmalloc_32_user);
    
    
    /*
     * small helper routine , copy contents to buf from addr.
     * If the page is not present, fill zero.
     */
    
    static int aligned_vread(char *buf, char *addr, unsigned long count)
    {
    	struct page *p;
    	int copied = 0;
    
    	while (count) {
    		unsigned long offset, length;
    
    		offset = offset_in_page(addr);
    		length = PAGE_SIZE - offset;
    		if (length > count)
    			length = count;
    		p = vmalloc_to_page(addr);
    		/*
    		 * To do safe access to this _mapped_ area, we need
    		 * lock. But adding lock here means that we need to add
    		 * overhead of vmalloc()/vfree() calles for this _debug_
    		 * interface, rarely used. Instead of that, we'll use
    		 * kmap() and get small overhead in this access function.
    		 */
    		if (p) {
    			/*
    			 * we can expect USER0 is not used (see vread/vwrite's
    			 * function description)
    			 */
    			void *map = kmap_atomic(p);
    			memcpy(buf, map + offset, length);
    			kunmap_atomic(map);
    		} else
    			memset(buf, 0, length);
    
    		addr += length;
    		buf += length;
    		copied += length;
    		count -= length;
    	}
    	return copied;
    }
    
    static int aligned_vwrite(char *buf, char *addr, unsigned long count)
    {
    	struct page *p;
    	int copied = 0;
    
    	while (count) {
    		unsigned long offset, length;
    
    		offset = offset_in_page(addr);
    		length = PAGE_SIZE - offset;
    		if (length > count)
    			length = count;
    		p = vmalloc_to_page(addr);
    		/*
    		 * To do safe access to this _mapped_ area, we need
    		 * lock. But adding lock here means that we need to add
    		 * overhead of vmalloc()/vfree() calles for this _debug_
    		 * interface, rarely used. Instead of that, we'll use
    		 * kmap() and get small overhead in this access function.
    		 */
    		if (p) {
    			/*
    			 * we can expect USER0 is not used (see vread/vwrite's
    			 * function description)
    			 */
    			void *map = kmap_atomic(p);
    			memcpy(map + offset, buf, length);
    			kunmap_atomic(map);
    		}
    		addr += length;
    		buf += length;
    		copied += length;
    		count -= length;
    	}
    	return copied;
    }
    
    /**
     *	vread() -  read vmalloc area in a safe way.
     *	@buf:		buffer for reading data
     *	@addr:		vm address.
     *	@count:		number of bytes to be read.
     *
     *	Returns # of bytes which addr and buf should be increased.
     *	(same number to @count). Returns 0 if [addr...addr+count) doesn't
     *	includes any intersect with alive vmalloc area.
     *
     *	This function checks that addr is a valid vmalloc'ed area, and
     *	copy data from that area to a given buffer. If the given memory range
     *	of [addr...addr+count) includes some valid address, data is copied to
     *	proper area of @buf. If there are memory holes, they'll be zero-filled.
     *	IOREMAP area is treated as memory hole and no copy is done.
     *
     *	If [addr...addr+count) doesn't includes any intersects with alive
     *	vm_struct area, returns 0. @buf should be kernel's buffer.
     *
     *	Note: In usual ops, vread() is never necessary because the caller
     *	should know vmalloc() area is valid and can use memcpy().
     *	This is for routines which have to access vmalloc area without
     *	any informaion, as /dev/kmem.
     *
     */
    
    long vread(char *buf, char *addr, unsigned long count)
    {
    	struct vmap_area *va;
    	struct vm_struct *vm;
    	char *vaddr, *buf_start = buf;
    	unsigned long buflen = count;
    	unsigned long n;
    
    	/* Don't allow overflow */
    	if ((unsigned long) addr + count < count)
    		count = -(unsigned long) addr;
    
    	spin_lock(&vmap_area_lock);
    	list_for_each_entry(va, &vmap_area_list, list) {
    		if (!count)
    			break;
    
    		if (!(va->flags & VM_VM_AREA))
    			continue;
    
    		vm = va->vm;
    		vaddr = (char *) vm->addr;
    		if (addr >= vaddr + get_vm_area_size(vm))
    			continue;
    		while (addr < vaddr) {
    			if (count == 0)
    				goto finished;
    			*buf = '\0';
    			buf++;
    			addr++;
    			count--;
    		}
    		n = vaddr + get_vm_area_size(vm) - addr;
    		if (n > count)
    			n = count;
    		if (!(vm->flags & VM_IOREMAP))
    			aligned_vread(buf, addr, n);
    		else /* IOREMAP area is treated as memory hole */
    			memset(buf, 0, n);
    		buf += n;
    		addr += n;
    		count -= n;
    	}
    finished:
    	spin_unlock(&vmap_area_lock);
    
    	if (buf == buf_start)
    		return 0;
    	/* zero-fill memory holes */
    	if (buf != buf_start + buflen)
    		memset(buf, 0, buflen - (buf - buf_start));
    
    	return buflen;
    }
    
    /**
     *	vwrite() -  write vmalloc area in a safe way.
     *	@buf:		buffer for source data
     *	@addr:		vm address.
     *	@count:		number of bytes to be read.
     *
     *	Returns # of bytes which addr and buf should be incresed.
     *	(same number to @count).
     *	If [addr...addr+count) doesn't includes any intersect with valid
     *	vmalloc area, returns 0.
     *
     *	This function checks that addr is a valid vmalloc'ed area, and
     *	copy data from a buffer to the given addr. If specified range of
     *	[addr...addr+count) includes some valid address, data is copied from
     *	proper area of @buf. If there are memory holes, no copy to hole.
     *	IOREMAP area is treated as memory hole and no copy is done.
     *
     *	If [addr...addr+count) doesn't includes any intersects with alive
     *	vm_struct area, returns 0. @buf should be kernel's buffer.
     *
     *	Note: In usual ops, vwrite() is never necessary because the caller
     *	should know vmalloc() area is valid and can use memcpy().
     *	This is for routines which have to access vmalloc area without
     *	any informaion, as /dev/kmem.
     */
    
    long vwrite(char *buf, char *addr, unsigned long count)
    {
    	struct vmap_area *va;
    	struct vm_struct *vm;
    	char *vaddr;
    	unsigned long n, buflen;
    	int copied = 0;
    
    	/* Don't allow overflow */
    	if ((unsigned long) addr + count < count)
    		count = -(unsigned long) addr;
    	buflen = count;
    
    	spin_lock(&vmap_area_lock);
    	list_for_each_entry(va, &vmap_area_list, list) {
    		if (!count)
    			break;
    
    		if (!(va->flags & VM_VM_AREA))
    			continue;
    
    		vm = va->vm;
    		vaddr = (char *) vm->addr;
    		if (addr >= vaddr + get_vm_area_size(vm))
    			continue;
    		while (addr < vaddr) {
    			if (count == 0)
    				goto finished;
    			buf++;
    			addr++;
    			count--;
    		}
    		n = vaddr + get_vm_area_size(vm) - addr;
    		if (n > count)
    			n = count;
    		if (!(vm->flags & VM_IOREMAP)) {
    			aligned_vwrite(buf, addr, n);
    			copied++;
    		}
    		buf += n;
    		addr += n;
    		count -= n;
    	}
    finished:
    	spin_unlock(&vmap_area_lock);
    	if (!copied)
    		return 0;
    	return buflen;
    }
    
    /**
     *	remap_vmalloc_range_partial  -  map vmalloc pages to userspace
     *	@vma:		vma to cover
     *	@uaddr:		target user address to start at
     *	@kaddr:		virtual address of vmalloc kernel memory
     *	@pgoff:		offset from @kaddr to start at
     *	@size:		size of map area
     *
     *	Returns:	0 for success, -Exxx on failure
     *
     *	This function checks that @kaddr is a valid vmalloc'ed area,
     *	and that it is big enough to cover the range starting at
     *	@uaddr in @vma. Will return failure if that criteria isn't
     *	met.
     *
     *	Similar to remap_pfn_range() (see mm/memory.c)
     */
    int remap_vmalloc_range_partial(struct vm_area_struct *vma, unsigned long uaddr,
    				void *kaddr, unsigned long pgoff,
    				unsigned long size)
    {
    	struct vm_struct *area;
    	unsigned long off;
    	unsigned long end_index;
    
    	if (check_shl_overflow(pgoff, PAGE_SHIFT, &off))
    		return -EINVAL;
    
    	size = PAGE_ALIGN(size);
    
    	if (!PAGE_ALIGNED(uaddr) || !PAGE_ALIGNED(kaddr))
    		return -EINVAL;
    
    	area = find_vm_area(kaddr);
    	if (!area)
    		return -EINVAL;
    
    	if (!(area->flags & VM_USERMAP))
    		return -EINVAL;
    
    	if (check_add_overflow(size, off, &end_index) ||
    	    end_index > get_vm_area_size(area))
    		return -EINVAL;
    	kaddr += off;
    
    	do {
    		struct page *page = vmalloc_to_page(kaddr);
    		int ret;
    
    		ret = vm_insert_page(vma, uaddr, page);
    		if (ret)
    			return ret;
    
    		uaddr += PAGE_SIZE;
    		kaddr += PAGE_SIZE;
    		size -= PAGE_SIZE;
    	} while (size > 0);
    
    	vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
    
    	return 0;
    }
    EXPORT_SYMBOL(remap_vmalloc_range_partial);
    
    /**
     *	remap_vmalloc_range  -  map vmalloc pages to userspace
     *	@vma:		vma to cover (map full range of vma)
     *	@addr:		vmalloc memory
     *	@pgoff:		number of pages into addr before first page to map
     *
     *	Returns:	0 for success, -Exxx on failure
     *
     *	This function checks that addr is a valid vmalloc'ed area, and
     *	that it is big enough to cover the vma. Will return failure if
     *	that criteria isn't met.
     *
     *	Similar to remap_pfn_range() (see mm/memory.c)
     */
    int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
    						unsigned long pgoff)
    {
    	return remap_vmalloc_range_partial(vma, vma->vm_start,
    					   addr, pgoff,
    					   vma->vm_end - vma->vm_start);
    }
    EXPORT_SYMBOL(remap_vmalloc_range);
    
    /**
     *	remap_vmalloc_hugepage_range_partial - map vmalloc hugepages
     *	to userspace
     *	@vma:		vma to cover
     *	@uaddr:		target user address to start at
     *	@kaddr:		virtual address of vmalloc hugepage kernel memory
     *	@size:		size of map area
     *
     *	Returns:	0 for success, -Exxx on failure
     *
     *	This function checks that @kaddr is a valid vmalloc'ed area,
     *	and that it is big enough to cover the range starting at
     *	@uaddr in @vma. Will return failure if that criteria isn't
     *	met.
     *
     *	Similar to remap_pfn_range() (see mm/memory.c)
     */
    int remap_vmalloc_hugepage_range_partial(struct vm_area_struct *vma,
    					 unsigned long uaddr, void *kaddr, unsigned long size)
    {
    	struct vm_struct *area;
    
    	size = PMD_ALIGN(size);
    
    	if (!PMD_ALIGNED(uaddr) || !PMD_ALIGNED(kaddr))
    		return -EINVAL;
    
    	area = find_vm_area(kaddr);
    	if (!area)
    		return -EINVAL;
    
    	if (!(area->flags & VM_USERMAP))
    		return -EINVAL;
    
    	if (kaddr + size > area->addr + get_vm_area_size(area))
    		return -EINVAL;
    
    	do {
    		struct page *page = vmalloc_to_hugepage(kaddr);
    		int ret;
    
    		ret = vm_insert_page(vma, uaddr, page);
    		if (ret)
    			return ret;
    
    		uaddr += PMD_SIZE;
    		kaddr += PMD_SIZE;
    		size -= PMD_SIZE;
    	} while (size > 0);
    
    	vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
    
    	return 0;
    }
    EXPORT_SYMBOL(remap_vmalloc_hugepage_range_partial);
    
    /**
     *	remap_vmalloc_hugepage_range - map vmalloc hugepages to userspace
     *	@vma:           vma to cover (map full range of vma)
     *	@addr:          vmalloc memory
     *	@pgoff:         number of hugepages into addr before first page to map
     *
     *	Returns:        0 for success, -Exxx on failure
     *
     *	This function checks that addr is a valid vmalloc'ed area, and
     *	that it is big enough to cover the vma. Will return failure if
     *	that criteria isn't met.
     *
     *	Similar to remap_pfn_range() (see mm/memory.c)
     */
    int remap_vmalloc_hugepage_range(struct vm_area_struct *vma, void *addr,
    				 unsigned long pgoff)
    {
    	return remap_vmalloc_hugepage_range_partial(vma, vma->vm_start,
    						    addr + (pgoff << PMD_SHIFT),
    						    vma->vm_end - vma->vm_start);
    }
    EXPORT_SYMBOL(remap_vmalloc_hugepage_range);
    
    /*
     * Implement stubs for vmalloc_sync_[un]mappings () if the architecture chose
     * not to have one.
     *
     * The purpose of this function is to make sure the vmalloc area
     * mappings are identical in all page-tables in the system.
     */
    void __weak vmalloc_sync_mappings(void)
    {
    }
    
    void __weak vmalloc_sync_unmappings(void)
    {
    }
    
    static int f(pte_t *pte, pgtable_t table, unsigned long addr, void *data)
    {
    	pte_t ***p = data;
    
    	if (p) {
    		*(*p) = pte;
    		(*p)++;
    	}
    	return 0;
    }
    
    /**
     *	alloc_vm_area - allocate a range of kernel address space
     *	@size:		size of the area
     *	@ptes:		returns the PTEs for the address space
     *
     *	Returns:	NULL on failure, vm_struct on success
     *
     *	This function reserves a range of kernel address space, and
     *	allocates pagetables to map that range.  No actual mappings
     *	are created.
     *
     *	If @ptes is non-NULL, pointers to the PTEs (in init_mm)
     *	allocated for the VM area are returned.
     */
    struct vm_struct *alloc_vm_area(size_t size, pte_t **ptes)
    {
    	struct vm_struct *area;
    
    	area = get_vm_area_caller(size, VM_IOREMAP,
    				__builtin_return_address(0));
    	if (area == NULL)
    		return NULL;
    
    	/*
    	 * This ensures that page tables are constructed for this region
    	 * of kernel virtual address space and mapped into init_mm.
    	 */
    	if (apply_to_page_range(&init_mm, (unsigned long)area->addr,
    				size, f, ptes ? &ptes : NULL)) {
    		free_vm_area(area);
    		return NULL;
    	}
    
    	return area;
    }
    EXPORT_SYMBOL_GPL(alloc_vm_area);
    
    void free_vm_area(struct vm_struct *area)
    {
    	struct vm_struct *ret;
    	ret = remove_vm_area(area->addr);
    	BUG_ON(ret != area);
    	kfree(area);
    }
    EXPORT_SYMBOL_GPL(free_vm_area);
    
    #ifdef CONFIG_SMP
    static struct vmap_area *node_to_va(struct rb_node *n)
    {
    	return rb_entry_safe(n, struct vmap_area, rb_node);
    }
    
    /**
     * pvm_find_va_enclose_addr - find the vmap_area @addr belongs to
     * @addr: target address
     *
     * Returns: vmap_area if it is found. If there is no such area
     *   the first highest(reverse order) vmap_area is returned
     *   i.e. va->va_start < addr && va->va_end < addr or NULL
     *   if there are no any areas before @addr.
     */
    static struct vmap_area *
    pvm_find_va_enclose_addr(unsigned long addr)
    {
    	struct vmap_area *va, *tmp;
    	struct rb_node *n;
    
    	n = free_vmap_area_root.rb_node;
    	va = NULL;
    
    	while (n) {
    		tmp = rb_entry(n, struct vmap_area, rb_node);
    		if (tmp->va_start <= addr) {
    			va = tmp;
    			if (tmp->va_end >= addr)
    				break;
    
    			n = n->rb_right;
    		} else {
    			n = n->rb_left;
    		}
    	}
    
    	return va;
    }
    
    /**
     * pvm_determine_end_from_reverse - find the highest aligned address
     * of free block below VMALLOC_END
     * @va:
     *   in - the VA we start the search(reverse order);
     *   out - the VA with the highest aligned end address.
     *
     * Returns: determined end address within vmap_area
     */
    static unsigned long
    pvm_determine_end_from_reverse(struct vmap_area **va, unsigned long align)
    {
    	unsigned long vmalloc_end = VMALLOC_END & ~(align - 1);
    	unsigned long addr;
    
    	if (likely(*va)) {
    		list_for_each_entry_from_reverse((*va),
    				&free_vmap_area_list, list) {
    			addr = min((*va)->va_end & ~(align - 1), vmalloc_end);
    			if ((*va)->va_start < addr)
    				return addr;
    		}
    	}
    
    	return 0;
    }
    
    /**
     * pcpu_get_vm_areas - allocate vmalloc areas for percpu allocator
     * @offsets: array containing offset of each area
     * @sizes: array containing size of each area
     * @nr_vms: the number of areas to allocate
     * @align: alignment, all entries in @offsets and @sizes must be aligned to this
     *
     * Returns: kmalloc'd vm_struct pointer array pointing to allocated
     *	    vm_structs on success, %NULL on failure
     *
     * Percpu allocator wants to use congruent vm areas so that it can
     * maintain the offsets among percpu areas.  This function allocates
     * congruent vmalloc areas for it with GFP_KERNEL.  These areas tend to
     * be scattered pretty far, distance between two areas easily going up
     * to gigabytes.  To avoid interacting with regular vmallocs, these
     * areas are allocated from top.
     *
     * Despite its complicated look, this allocator is rather simple. It
     * does everything top-down and scans free blocks from the end looking
     * for matching base. While scanning, if any of the areas do not fit the
     * base address is pulled down to fit the area. Scanning is repeated till
     * all the areas fit and then all necessary data structures are inserted
     * and the result is returned.
     */
    struct vm_struct **pcpu_get_vm_areas(const unsigned long *offsets,
    				     const size_t *sizes, int nr_vms,
    				     size_t align)
    {
    	const unsigned long vmalloc_start = ALIGN(VMALLOC_START, align);
    	const unsigned long vmalloc_end = VMALLOC_END & ~(align - 1);
    	struct vmap_area **vas, *va;
    	struct vm_struct **vms;
    	int area, area2, last_area, term_area;
    	unsigned long base, start, size, end, last_end;
    	bool purged = false;
    	enum fit_type type;
    
    	/* verify parameters and allocate data structures */
    	BUG_ON(offset_in_page(align) || !is_power_of_2(align));
    	for (last_area = 0, area = 0; area < nr_vms; area++) {
    		start = offsets[area];
    		end = start + sizes[area];
    
    		/* is everything aligned properly? */
    		BUG_ON(!IS_ALIGNED(offsets[area], align));
    		BUG_ON(!IS_ALIGNED(sizes[area], align));
    
    		/* detect the area with the highest address */
    		if (start > offsets[last_area])
    			last_area = area;
    
    		for (area2 = area + 1; area2 < nr_vms; area2++) {
    			unsigned long start2 = offsets[area2];
    			unsigned long end2 = start2 + sizes[area2];
    
    			BUG_ON(start2 < end && start < end2);
    		}
    	}
    	last_end = offsets[last_area] + sizes[last_area];
    
    	if (vmalloc_end - vmalloc_start < last_end) {
    		WARN_ON(true);
    		return NULL;
    	}
    
    	vms = kcalloc(nr_vms, sizeof(vms[0]), GFP_KERNEL);
    	vas = kcalloc(nr_vms, sizeof(vas[0]), GFP_KERNEL);
    	if (!vas || !vms)
    		goto err_free2;
    
    	for (area = 0; area < nr_vms; area++) {
    		vas[area] = kmem_cache_zalloc(vmap_area_cachep, GFP_KERNEL);
    		vms[area] = kzalloc(sizeof(struct vm_struct), GFP_KERNEL);
    		if (!vas[area] || !vms[area])
    			goto err_free;
    	}
    retry:
    	spin_lock(&vmap_area_lock);
    
    	/* start scanning - we scan from the top, begin with the last area */
    	area = term_area = last_area;
    	start = offsets[area];
    	end = start + sizes[area];
    
    	va = pvm_find_va_enclose_addr(vmalloc_end);
    	base = pvm_determine_end_from_reverse(&va, align) - end;
    
    	while (true) {
    		/*
    		 * base might have underflowed, add last_end before
    		 * comparing.
    		 */
    		if (base + last_end < vmalloc_start + last_end)
    			goto overflow;
    
    		/*
    		 * Fitting base has not been found.
    		 */
    		if (va == NULL)
    			goto overflow;
    
    		/*
    		 * If required width exeeds current VA block, move
    		 * base downwards and then recheck.
    		 */
    		if (base + end > va->va_end) {
    			base = pvm_determine_end_from_reverse(&va, align) - end;
    			term_area = area;
    			continue;
    		}
    
    		/*
    		 * If this VA does not fit, move base downwards and recheck.
    		 */
    		if (base + start < va->va_start) {
    			va = node_to_va(rb_prev(&va->rb_node));
    			base = pvm_determine_end_from_reverse(&va, align) - end;
    			term_area = area;
    			continue;
    		}
    
    		/*
    		 * This area fits, move on to the previous one.  If
    		 * the previous one is the terminal one, we're done.
    		 */
    		area = (area + nr_vms - 1) % nr_vms;
    		if (area == term_area)
    			break;
    
    		start = offsets[area];
    		end = start + sizes[area];
    		va = pvm_find_va_enclose_addr(base + end);
    	}
    
    	/* we've found a fitting base, insert all va's */
    	for (area = 0; area < nr_vms; area++) {
    		int ret;
    
    		start = base + offsets[area];
    		size = sizes[area];
    
    		va = pvm_find_va_enclose_addr(start);
    		if (WARN_ON_ONCE(va == NULL))
    			/* It is a BUG(), but trigger recovery instead. */
    			goto recovery;
    
    		type = classify_va_fit_type(va, start, size);
    		if (WARN_ON_ONCE(type == NOTHING_FIT))
    			/* It is a BUG(), but trigger recovery instead. */
    			goto recovery;
    
    		ret = adjust_va_to_fit_type(va, start, size, type);
    		if (unlikely(ret))
    			goto recovery;
    
    		/* Allocated area. */
    		va = vas[area];
    		va->va_start = start;
    		va->va_end = start + size;
    
    		insert_vmap_area(va, &vmap_area_root, &vmap_area_list);
    	}
    
    	spin_unlock(&vmap_area_lock);
    
    	/* insert all vm's */
    	for (area = 0; area < nr_vms; area++)
    		setup_vmalloc_vm(vms[area], vas[area], VM_ALLOC,
    				 pcpu_get_vm_areas);
    
    	kfree(vas);
    	return vms;
    
    recovery:
    	/* Remove previously inserted areas. */
    	while (area--) {
    		__free_vmap_area(vas[area]);
    		vas[area] = NULL;
    	}
    
    overflow:
    	spin_unlock(&vmap_area_lock);
    	if (!purged) {
    		purge_vmap_area_lazy();
    		purged = true;
    
    		/* Before "retry", check if we recover. */
    		for (area = 0; area < nr_vms; area++) {
    			if (vas[area])
    				continue;
    
    			vas[area] = kmem_cache_zalloc(
    				vmap_area_cachep, GFP_KERNEL);
    			if (!vas[area])
    				goto err_free;
    		}
    
    		goto retry;
    	}
    
    err_free:
    	for (area = 0; area < nr_vms; area++) {
    		if (vas[area])
    			kmem_cache_free(vmap_area_cachep, vas[area]);
    
    		kfree(vms[area]);
    	}
    err_free2:
    	kfree(vas);
    	kfree(vms);
    	return NULL;
    }
    
    /**
     * pcpu_free_vm_areas - free vmalloc areas for percpu allocator
     * @vms: vm_struct pointer array returned by pcpu_get_vm_areas()
     * @nr_vms: the number of allocated areas
     *
     * Free vm_structs and the array allocated by pcpu_get_vm_areas().
     */
    void pcpu_free_vm_areas(struct vm_struct **vms, int nr_vms)
    {
    	int i;
    
    	for (i = 0; i < nr_vms; i++)
    		free_vm_area(vms[i]);
    	kfree(vms);
    }
    #endif	/* CONFIG_SMP */
    
    #ifdef CONFIG_PROC_FS
    static void *s_start(struct seq_file *m, loff_t *pos)
    	__acquires(&vmap_area_lock)
    {
    	spin_lock(&vmap_area_lock);
    	return seq_list_start(&vmap_area_list, *pos);
    }
    
    static void *s_next(struct seq_file *m, void *p, loff_t *pos)
    {
    	return seq_list_next(p, &vmap_area_list, pos);
    }
    
    static void s_stop(struct seq_file *m, void *p)
    	__releases(&vmap_area_lock)
    {
    	spin_unlock(&vmap_area_lock);
    }
    
    static void show_numa_info(struct seq_file *m, struct vm_struct *v)
    {
    	if (IS_ENABLED(CONFIG_NUMA)) {
    		unsigned int nr, *counters = m->private;
    
    		if (!counters)
    			return;
    
    		if (v->flags & VM_UNINITIALIZED)
    			return;
    		/* Pair with smp_wmb() in clear_vm_uninitialized_flag() */
    		smp_rmb();
    
    		memset(counters, 0, nr_node_ids * sizeof(unsigned int));
    
    		for (nr = 0; nr < v->nr_pages; nr++)
    			counters[page_to_nid(v->pages[nr])]++;
    
    		for_each_node_state(nr, N_HIGH_MEMORY)
    			if (counters[nr])
    				seq_printf(m, " N%u=%u", nr, counters[nr]);
    	}
    }
    
    static int s_show(struct seq_file *m, void *p)
    {
    	struct vmap_area *va;
    	struct vm_struct *v;
    
    	va = list_entry(p, struct vmap_area, list);
    
    	/*
    	 * s_show can encounter race with remove_vm_area, !VM_VM_AREA on
    	 * behalf of vmap area is being tear down or vm_map_ram allocation.
    	 */
    	if (!(va->flags & VM_VM_AREA)) {
    		seq_printf(m, "0x%pK-0x%pK %7ld %s\n",
    			(void *)va->va_start, (void *)va->va_end,
    			va->va_end - va->va_start,
    			va->flags & VM_LAZY_FREE ? "unpurged vm_area" : "vm_map_ram");
    
    		return 0;
    	}
    
    	v = va->vm;
    
    	seq_printf(m, "0x%pK-0x%pK %7ld",
    		v->addr, v->addr + v->size, v->size);
    
    	if (v->caller)
    		seq_printf(m, " %pS", v->caller);
    
    	if (v->nr_pages)
    		seq_printf(m, " pages=%d", v->nr_pages);
    
    	if (v->phys_addr)
    		seq_printf(m, " phys=%pa", &v->phys_addr);
    
    	if (v->flags & VM_IOREMAP)
    		seq_puts(m, " ioremap");
    
    	if (v->flags & VM_ALLOC)
    		seq_puts(m, " vmalloc");
    
    	if (v->flags & VM_MAP)
    		seq_puts(m, " vmap");
    
    	if (v->flags & VM_USERMAP)
    		seq_puts(m, " user");
    
    	if (is_vmalloc_addr(v->pages))
    		seq_puts(m, " vpages");
    
    	if (is_vmalloc_huge(v->flags))
    		seq_printf(m, " order=%d", PMD_SHIFT - PAGE_SHIFT);
    
    	show_numa_info(m, v);
    	seq_putc(m, '\n');
    	return 0;
    }
    
    static const struct seq_operations vmalloc_op = {
    	.start = s_start,
    	.next = s_next,
    	.stop = s_stop,
    	.show = s_show,
    };
    
    static int __init proc_vmalloc_init(void)
    {
    	if (IS_ENABLED(CONFIG_NUMA))
    		proc_create_seq_private("vmallocinfo", 0400, NULL,
    				&vmalloc_op,
    				nr_node_ids * sizeof(unsigned int), NULL);
    	else
    		proc_create_seq("vmallocinfo", 0400, NULL, &vmalloc_op);
    	return 0;
    }
    module_init(proc_vmalloc_init);
    
    #endif