Skip to content
Snippets Groups Projects
Select Git revision
  • d8be75663cec0069b85f80191abd2682ce4a512f
  • openEuler-1.0-LTS default protected
  • openEuler-22.09
  • OLK-5.10
  • openEuler-22.03-LTS
  • openEuler-22.03-LTS-Ascend
  • master
  • openEuler-22.03-LTS-LoongArch-NW
  • openEuler-22.09-HCK
  • openEuler-20.03-LTS-SP3
  • openEuler-21.09
  • openEuler-21.03
  • openEuler-20.09
  • 4.19.90-2210.5.0
  • 5.10.0-123.0.0
  • 5.10.0-60.63.0
  • 5.10.0-60.62.0
  • 4.19.90-2210.4.0
  • 5.10.0-121.0.0
  • 5.10.0-60.61.0
  • 4.19.90-2210.3.0
  • 5.10.0-60.60.0
  • 5.10.0-120.0.0
  • 5.10.0-60.59.0
  • 5.10.0-119.0.0
  • 4.19.90-2210.2.0
  • 4.19.90-2210.1.0
  • 5.10.0-118.0.0
  • 5.10.0-106.19.0
  • 5.10.0-60.58.0
  • 4.19.90-2209.6.0
  • 5.10.0-106.18.0
  • 5.10.0-106.17.0
33 results

gfp.h

Blame
  • gfp.h 22.72 KiB
    /* SPDX-License-Identifier: GPL-2.0 */
    #ifndef __LINUX_GFP_H
    #define __LINUX_GFP_H
    
    #include <linux/mmdebug.h>
    #include <linux/mmzone.h>
    #include <linux/stddef.h>
    #include <linux/linkage.h>
    #include <linux/topology.h>
    
    struct vm_area_struct;
    
    /*
     * In case of changes, please don't forget to update
     * include/trace/events/mmflags.h and tools/perf/builtin-kmem.c
     */
    
    /* Plain integer GFP bitmasks. Do not use this directly. */
    #define ___GFP_DMA		0x01u
    #define ___GFP_HIGHMEM		0x02u
    #define ___GFP_DMA32		0x04u
    #define ___GFP_MOVABLE		0x08u
    #define ___GFP_RECLAIMABLE	0x10u
    #define ___GFP_HIGH		0x20u
    #define ___GFP_IO		0x40u
    #define ___GFP_FS		0x80u
    #define ___GFP_COLD		0x100u
    #define ___GFP_NOWARN		0x200u
    #define ___GFP_RETRY_MAYFAIL	0x400u
    #define ___GFP_NOFAIL		0x800u
    #define ___GFP_NORETRY		0x1000u
    #define ___GFP_MEMALLOC		0x2000u
    #define ___GFP_COMP		0x4000u
    #define ___GFP_ZERO		0x8000u
    #define ___GFP_NOMEMALLOC	0x10000u
    #define ___GFP_HARDWALL		0x20000u
    #define ___GFP_THISNODE		0x40000u
    #define ___GFP_ATOMIC		0x80000u
    #define ___GFP_ACCOUNT		0x100000u
    #define ___GFP_DIRECT_RECLAIM	0x400000u
    #define ___GFP_WRITE		0x800000u
    #define ___GFP_KSWAPD_RECLAIM	0x1000000u
    #ifdef CONFIG_LOCKDEP
    #define ___GFP_NOLOCKDEP	0x2000000u
    #else
    #define ___GFP_NOLOCKDEP	0
    #endif
    /* If the above are modified, __GFP_BITS_SHIFT may need updating */
    
    /*
     * Physical address zone modifiers (see linux/mmzone.h - low four bits)
     *
     * Do not put any conditional on these. If necessary modify the definitions
     * without the underscores and use them consistently. The definitions here may
     * be used in bit comparisons.
     */
    #define __GFP_DMA	((__force gfp_t)___GFP_DMA)
    #define __GFP_HIGHMEM	((__force gfp_t)___GFP_HIGHMEM)
    #define __GFP_DMA32	((__force gfp_t)___GFP_DMA32)
    #define __GFP_MOVABLE	((__force gfp_t)___GFP_MOVABLE)  /* ZONE_MOVABLE allowed */
    #define GFP_ZONEMASK	(__GFP_DMA|__GFP_HIGHMEM|__GFP_DMA32|__GFP_MOVABLE)
    
    /*
     * Page mobility and placement hints
     *
     * These flags provide hints about how mobile the page is. Pages with similar
     * mobility are placed within the same pageblocks to minimise problems due
     * to external fragmentation.
     *
     * __GFP_MOVABLE (also a zone modifier) indicates that the page can be
     *   moved by page migration during memory compaction or can be reclaimed.
     *
     * __GFP_RECLAIMABLE is used for slab allocations that specify
     *   SLAB_RECLAIM_ACCOUNT and whose pages can be freed via shrinkers.
     *
     * __GFP_WRITE indicates the caller intends to dirty the page. Where possible,
     *   these pages will be spread between local zones to avoid all the dirty
     *   pages being in one zone (fair zone allocation policy).
     *
     * __GFP_HARDWALL enforces the cpuset memory allocation policy.
     *
     * __GFP_THISNODE forces the allocation to be satisified from the requested
     *   node with no fallbacks or placement policy enforcements.
     *
     * __GFP_ACCOUNT causes the allocation to be accounted to kmemcg.
     */
    #define __GFP_RECLAIMABLE ((__force gfp_t)___GFP_RECLAIMABLE)
    #define __GFP_WRITE	((__force gfp_t)___GFP_WRITE)
    #define __GFP_HARDWALL   ((__force gfp_t)___GFP_HARDWALL)
    #define __GFP_THISNODE	((__force gfp_t)___GFP_THISNODE)
    #define __GFP_ACCOUNT	((__force gfp_t)___GFP_ACCOUNT)
    
    /*
     * Watermark modifiers -- controls access to emergency reserves
     *
     * __GFP_HIGH indicates that the caller is high-priority and that granting
     *   the request is necessary before the system can make forward progress.
     *   For example, creating an IO context to clean pages.
     *
     * __GFP_ATOMIC indicates that the caller cannot reclaim or sleep and is
     *   high priority. Users are typically interrupt handlers. This may be
     *   used in conjunction with __GFP_HIGH
     *
     * __GFP_MEMALLOC allows access to all memory. This should only be used when
     *   the caller guarantees the allocation will allow more memory to be freed
     *   very shortly e.g. process exiting or swapping. Users either should
     *   be the MM or co-ordinating closely with the VM (e.g. swap over NFS).
     *
     * __GFP_NOMEMALLOC is used to explicitly forbid access to emergency reserves.
     *   This takes precedence over the __GFP_MEMALLOC flag if both are set.
     */
    #define __GFP_ATOMIC	((__force gfp_t)___GFP_ATOMIC)
    #define __GFP_HIGH	((__force gfp_t)___GFP_HIGH)
    #define __GFP_MEMALLOC	((__force gfp_t)___GFP_MEMALLOC)
    #define __GFP_NOMEMALLOC ((__force gfp_t)___GFP_NOMEMALLOC)
    
    /*
     * Reclaim modifiers
     *
     * __GFP_IO can start physical IO.
     *
     * __GFP_FS can call down to the low-level FS. Clearing the flag avoids the
     *   allocator recursing into the filesystem which might already be holding
     *   locks.
     *
     * __GFP_DIRECT_RECLAIM indicates that the caller may enter direct reclaim.
     *   This flag can be cleared to avoid unnecessary delays when a fallback
     *   option is available.
     *
     * __GFP_KSWAPD_RECLAIM indicates that the caller wants to wake kswapd when
     *   the low watermark is reached and have it reclaim pages until the high
     *   watermark is reached. A caller may wish to clear this flag when fallback
     *   options are available and the reclaim is likely to disrupt the system. The
     *   canonical example is THP allocation where a fallback is cheap but
     *   reclaim/compaction may cause indirect stalls.
     *
     * __GFP_RECLAIM is shorthand to allow/forbid both direct and kswapd reclaim.
     *
     * The default allocator behavior depends on the request size. We have a concept
     * of so called costly allocations (with order > PAGE_ALLOC_COSTLY_ORDER).
     * !costly allocations are too essential to fail so they are implicitly
     * non-failing by default (with some exceptions like OOM victims might fail so
     * the caller still has to check for failures) while costly requests try to be
     * not disruptive and back off even without invoking the OOM killer.
     * The following three modifiers might be used to override some of these
     * implicit rules
     *
     * __GFP_NORETRY: The VM implementation will try only very lightweight
     *   memory direct reclaim to get some memory under memory pressure (thus
     *   it can sleep). It will avoid disruptive actions like OOM killer. The
     *   caller must handle the failure which is quite likely to happen under
     *   heavy memory pressure. The flag is suitable when failure can easily be
     *   handled at small cost, such as reduced throughput
     *
     * __GFP_RETRY_MAYFAIL: The VM implementation will retry memory reclaim
     *   procedures that have previously failed if there is some indication
     *   that progress has been made else where.  It can wait for other
     *   tasks to attempt high level approaches to freeing memory such as
     *   compaction (which removes fragmentation) and page-out.
     *   There is still a definite limit to the number of retries, but it is
     *   a larger limit than with __GFP_NORETRY.
     *   Allocations with this flag may fail, but only when there is
     *   genuinely little unused memory. While these allocations do not
     *   directly trigger the OOM killer, their failure indicates that
     *   the system is likely to need to use the OOM killer soon.  The
     *   caller must handle failure, but can reasonably do so by failing
     *   a higher-level request, or completing it only in a much less
     *   efficient manner.
     *   If the allocation does fail, and the caller is in a position to
     *   free some non-essential memory, doing so could benefit the system
     *   as a whole.
     *
     * __GFP_NOFAIL: The VM implementation _must_ retry infinitely: the caller
     *   cannot handle allocation failures. The allocation could block
     *   indefinitely but will never return with failure. Testing for
     *   failure is pointless.
     *   New users should be evaluated carefully (and the flag should be
     *   used only when there is no reasonable failure policy) but it is
     *   definitely preferable to use the flag rather than opencode endless
     *   loop around allocator.
     *   Using this flag for costly allocations is _highly_ discouraged.
     */
    #define __GFP_IO	((__force gfp_t)___GFP_IO)
    #define __GFP_FS	((__force gfp_t)___GFP_FS)
    #define __GFP_DIRECT_RECLAIM	((__force gfp_t)___GFP_DIRECT_RECLAIM) /* Caller can reclaim */
    #define __GFP_KSWAPD_RECLAIM	((__force gfp_t)___GFP_KSWAPD_RECLAIM) /* kswapd can wake */
    #define __GFP_RECLAIM ((__force gfp_t)(___GFP_DIRECT_RECLAIM|___GFP_KSWAPD_RECLAIM))
    #define __GFP_RETRY_MAYFAIL	((__force gfp_t)___GFP_RETRY_MAYFAIL)
    #define __GFP_NOFAIL	((__force gfp_t)___GFP_NOFAIL)
    #define __GFP_NORETRY	((__force gfp_t)___GFP_NORETRY)
    
    /*
     * Action modifiers
     *
     * __GFP_COLD indicates that the caller does not expect to be used in the near
     *   future. Where possible, a cache-cold page will be returned.
     *
     * __GFP_NOWARN suppresses allocation failure reports.
     *
     * __GFP_COMP address compound page metadata.
     *
     * __GFP_ZERO returns a zeroed page on success.
     */
    #define __GFP_COLD	((__force gfp_t)___GFP_COLD)
    #define __GFP_NOWARN	((__force gfp_t)___GFP_NOWARN)
    #define __GFP_COMP	((__force gfp_t)___GFP_COMP)
    #define __GFP_ZERO	((__force gfp_t)___GFP_ZERO)
    
    /* Disable lockdep for GFP context tracking */
    #define __GFP_NOLOCKDEP ((__force gfp_t)___GFP_NOLOCKDEP)
    
    /* Room for N __GFP_FOO bits */
    #define __GFP_BITS_SHIFT (25 + IS_ENABLED(CONFIG_LOCKDEP))
    #define __GFP_BITS_MASK ((__force gfp_t)((1 << __GFP_BITS_SHIFT) - 1))
    
    /*
     * Useful GFP flag combinations that are commonly used. It is recommended
     * that subsystems start with one of these combinations and then set/clear
     * __GFP_FOO flags as necessary.
     *
     * GFP_ATOMIC users can not sleep and need the allocation to succeed. A lower
     *   watermark is applied to allow access to "atomic reserves"
     *
     * GFP_KERNEL is typical for kernel-internal allocations. The caller requires
     *   ZONE_NORMAL or a lower zone for direct access but can direct reclaim.
     *
     * GFP_KERNEL_ACCOUNT is the same as GFP_KERNEL, except the allocation is
     *   accounted to kmemcg.
     *
     * GFP_NOWAIT is for kernel allocations that should not stall for direct
     *   reclaim, start physical IO or use any filesystem callback.
     *
     * GFP_NOIO will use direct reclaim to discard clean pages or slab pages
     *   that do not require the starting of any physical IO.
     *   Please try to avoid using this flag directly and instead use
     *   memalloc_noio_{save,restore} to mark the whole scope which cannot
     *   perform any IO with a short explanation why. All allocation requests
     *   will inherit GFP_NOIO implicitly.
     *
     * GFP_NOFS will use direct reclaim but will not use any filesystem interfaces.
     *   Please try to avoid using this flag directly and instead use
     *   memalloc_nofs_{save,restore} to mark the whole scope which cannot/shouldn't
     *   recurse into the FS layer with a short explanation why. All allocation
     *   requests will inherit GFP_NOFS implicitly.
     *
     * GFP_USER is for userspace allocations that also need to be directly
     *   accessibly by the kernel or hardware. It is typically used by hardware
     *   for buffers that are mapped to userspace (e.g. graphics) that hardware
     *   still must DMA to. cpuset limits are enforced for these allocations.
     *
     * GFP_DMA exists for historical reasons and should be avoided where possible.
     *   The flags indicates that the caller requires that the lowest zone be
     *   used (ZONE_DMA or 16M on x86-64). Ideally, this would be removed but
     *   it would require careful auditing as some users really require it and
     *   others use the flag to avoid lowmem reserves in ZONE_DMA and treat the
     *   lowest zone as a type of emergency reserve.
     *
     * GFP_DMA32 is similar to GFP_DMA except that the caller requires a 32-bit
     *   address.
     *
     * GFP_HIGHUSER is for userspace allocations that may be mapped to userspace,
     *   do not need to be directly accessible by the kernel but that cannot
     *   move once in use. An example may be a hardware allocation that maps
     *   data directly into userspace but has no addressing limitations.
     *
     * GFP_HIGHUSER_MOVABLE is for userspace allocations that the kernel does not
     *   need direct access to but can use kmap() when access is required. They
     *   are expected to be movable via page reclaim or page migration. Typically,
     *   pages on the LRU would also be allocated with GFP_HIGHUSER_MOVABLE.
     *
     * GFP_TRANSHUGE and GFP_TRANSHUGE_LIGHT are used for THP allocations. They are
     *   compound allocations that will generally fail quickly if memory is not
     *   available and will not wake kswapd/kcompactd on failure. The _LIGHT
     *   version does not attempt reclaim/compaction at all and is by default used
     *   in page fault path, while the non-light is used by khugepaged.
     */
    #define GFP_ATOMIC	(__GFP_HIGH|__GFP_ATOMIC|__GFP_KSWAPD_RECLAIM)
    #define GFP_KERNEL	(__GFP_RECLAIM | __GFP_IO | __GFP_FS)
    #define GFP_KERNEL_ACCOUNT (GFP_KERNEL | __GFP_ACCOUNT)
    #define GFP_NOWAIT	(__GFP_KSWAPD_RECLAIM)
    #define GFP_NOIO	(__GFP_RECLAIM)
    #define GFP_NOFS	(__GFP_RECLAIM | __GFP_IO)
    #define GFP_USER	(__GFP_RECLAIM | __GFP_IO | __GFP_FS | __GFP_HARDWALL)
    #define GFP_DMA		__GFP_DMA
    #define GFP_DMA32	__GFP_DMA32
    #define GFP_HIGHUSER	(GFP_USER | __GFP_HIGHMEM)
    #define GFP_HIGHUSER_MOVABLE	(GFP_HIGHUSER | __GFP_MOVABLE)
    #define GFP_TRANSHUGE_LIGHT	((GFP_HIGHUSER_MOVABLE | __GFP_COMP | \
    			 __GFP_NOMEMALLOC | __GFP_NOWARN) & ~__GFP_RECLAIM)
    #define GFP_TRANSHUGE	(GFP_TRANSHUGE_LIGHT | __GFP_DIRECT_RECLAIM)
    
    /* Convert GFP flags to their corresponding migrate type */
    #define GFP_MOVABLE_MASK (__GFP_RECLAIMABLE|__GFP_MOVABLE)
    #define GFP_MOVABLE_SHIFT 3
    
    static inline int gfpflags_to_migratetype(const gfp_t gfp_flags)
    {
    	VM_WARN_ON((gfp_flags & GFP_MOVABLE_MASK) == GFP_MOVABLE_MASK);
    	BUILD_BUG_ON((1UL << GFP_MOVABLE_SHIFT) != ___GFP_MOVABLE);
    	BUILD_BUG_ON((___GFP_MOVABLE >> GFP_MOVABLE_SHIFT) != MIGRATE_MOVABLE);
    
    	if (unlikely(page_group_by_mobility_disabled))
    		return MIGRATE_UNMOVABLE;
    
    	/* Group based on mobility */
    	return (gfp_flags & GFP_MOVABLE_MASK) >> GFP_MOVABLE_SHIFT;
    }
    #undef GFP_MOVABLE_MASK
    #undef GFP_MOVABLE_SHIFT
    
    static inline bool gfpflags_allow_blocking(const gfp_t gfp_flags)
    {
    	return !!(gfp_flags & __GFP_DIRECT_RECLAIM);
    }
    
    #ifdef CONFIG_HIGHMEM
    #define OPT_ZONE_HIGHMEM ZONE_HIGHMEM
    #else
    #define OPT_ZONE_HIGHMEM ZONE_NORMAL
    #endif
    
    #ifdef CONFIG_ZONE_DMA
    #define OPT_ZONE_DMA ZONE_DMA
    #else
    #define OPT_ZONE_DMA ZONE_NORMAL
    #endif
    
    #ifdef CONFIG_ZONE_DMA32
    #define OPT_ZONE_DMA32 ZONE_DMA32
    #else
    #define OPT_ZONE_DMA32 ZONE_NORMAL
    #endif
    
    /*
     * GFP_ZONE_TABLE is a word size bitstring that is used for looking up the
     * zone to use given the lowest 4 bits of gfp_t. Entries are GFP_ZONES_SHIFT
     * bits long and there are 16 of them to cover all possible combinations of
     * __GFP_DMA, __GFP_DMA32, __GFP_MOVABLE and __GFP_HIGHMEM.
     *
     * The zone fallback order is MOVABLE=>HIGHMEM=>NORMAL=>DMA32=>DMA.
     * But GFP_MOVABLE is not only a zone specifier but also an allocation
     * policy. Therefore __GFP_MOVABLE plus another zone selector is valid.
     * Only 1 bit of the lowest 3 bits (DMA,DMA32,HIGHMEM) can be set to "1".
     *
     *       bit       result
     *       =================
     *       0x0    => NORMAL
     *       0x1    => DMA or NORMAL
     *       0x2    => HIGHMEM or NORMAL
     *       0x3    => BAD (DMA+HIGHMEM)
     *       0x4    => DMA32 or DMA or NORMAL
     *       0x5    => BAD (DMA+DMA32)
     *       0x6    => BAD (HIGHMEM+DMA32)
     *       0x7    => BAD (HIGHMEM+DMA32+DMA)
     *       0x8    => NORMAL (MOVABLE+0)
     *       0x9    => DMA or NORMAL (MOVABLE+DMA)
     *       0xa    => MOVABLE (Movable is valid only if HIGHMEM is set too)
     *       0xb    => BAD (MOVABLE+HIGHMEM+DMA)
     *       0xc    => DMA32 (MOVABLE+DMA32)
     *       0xd    => BAD (MOVABLE+DMA32+DMA)
     *       0xe    => BAD (MOVABLE+DMA32+HIGHMEM)
     *       0xf    => BAD (MOVABLE+DMA32+HIGHMEM+DMA)
     *
     * GFP_ZONES_SHIFT must be <= 2 on 32 bit platforms.
     */
    
    #if defined(CONFIG_ZONE_DEVICE) && (MAX_NR_ZONES-1) <= 4
    /* ZONE_DEVICE is not a valid GFP zone specifier */
    #define GFP_ZONES_SHIFT 2
    #else
    #define GFP_ZONES_SHIFT ZONES_SHIFT
    #endif
    
    #if 16 * GFP_ZONES_SHIFT > BITS_PER_LONG
    #error GFP_ZONES_SHIFT too large to create GFP_ZONE_TABLE integer
    #endif
    
    #define GFP_ZONE_TABLE ( \
    	(ZONE_NORMAL << 0 * GFP_ZONES_SHIFT)				       \
    	| (OPT_ZONE_DMA << ___GFP_DMA * GFP_ZONES_SHIFT)		       \
    	| (OPT_ZONE_HIGHMEM << ___GFP_HIGHMEM * GFP_ZONES_SHIFT)	       \
    	| (OPT_ZONE_DMA32 << ___GFP_DMA32 * GFP_ZONES_SHIFT)		       \
    	| (ZONE_NORMAL << ___GFP_MOVABLE * GFP_ZONES_SHIFT)		       \
    	| (OPT_ZONE_DMA << (___GFP_MOVABLE | ___GFP_DMA) * GFP_ZONES_SHIFT)    \
    	| (ZONE_MOVABLE << (___GFP_MOVABLE | ___GFP_HIGHMEM) * GFP_ZONES_SHIFT)\
    	| (OPT_ZONE_DMA32 << (___GFP_MOVABLE | ___GFP_DMA32) * GFP_ZONES_SHIFT)\
    )
    
    /*
     * GFP_ZONE_BAD is a bitmap for all combinations of __GFP_DMA, __GFP_DMA32
     * __GFP_HIGHMEM and __GFP_MOVABLE that are not permitted. One flag per
     * entry starting with bit 0. Bit is set if the combination is not
     * allowed.
     */
    #define GFP_ZONE_BAD ( \
    	1 << (___GFP_DMA | ___GFP_HIGHMEM)				      \
    	| 1 << (___GFP_DMA | ___GFP_DMA32)				      \
    	| 1 << (___GFP_DMA32 | ___GFP_HIGHMEM)				      \
    	| 1 << (___GFP_DMA | ___GFP_DMA32 | ___GFP_HIGHMEM)		      \
    	| 1 << (___GFP_MOVABLE | ___GFP_HIGHMEM | ___GFP_DMA)		      \
    	| 1 << (___GFP_MOVABLE | ___GFP_DMA32 | ___GFP_DMA)		      \
    	| 1 << (___GFP_MOVABLE | ___GFP_DMA32 | ___GFP_HIGHMEM)		      \
    	| 1 << (___GFP_MOVABLE | ___GFP_DMA32 | ___GFP_DMA | ___GFP_HIGHMEM)  \
    )
    
    static inline enum zone_type gfp_zone(gfp_t flags)
    {
    	enum zone_type z;
    	int bit = (__force int) (flags & GFP_ZONEMASK);
    
    	z = (GFP_ZONE_TABLE >> (bit * GFP_ZONES_SHIFT)) &
    					 ((1 << GFP_ZONES_SHIFT) - 1);
    	VM_BUG_ON((GFP_ZONE_BAD >> bit) & 1);
    	return z;
    }
    
    /*
     * There is only one page-allocator function, and two main namespaces to
     * it. The alloc_page*() variants return 'struct page *' and as such
     * can allocate highmem pages, the *get*page*() variants return
     * virtual kernel addresses to the allocated page(s).
     */
    
    static inline int gfp_zonelist(gfp_t flags)
    {
    #ifdef CONFIG_NUMA
    	if (unlikely(flags & __GFP_THISNODE))
    		return ZONELIST_NOFALLBACK;
    #endif
    	return ZONELIST_FALLBACK;
    }
    
    /*
     * We get the zone list from the current node and the gfp_mask.
     * This zone list contains a maximum of MAXNODES*MAX_NR_ZONES zones.
     * There are two zonelists per node, one for all zones with memory and
     * one containing just zones from the node the zonelist belongs to.
     *
     * For the normal case of non-DISCONTIGMEM systems the NODE_DATA() gets
     * optimized to &contig_page_data at compile-time.
     */
    static inline struct zonelist *node_zonelist(int nid, gfp_t flags)
    {
    	return NODE_DATA(nid)->node_zonelists + gfp_zonelist(flags);
    }
    
    #ifndef HAVE_ARCH_FREE_PAGE
    static inline void arch_free_page(struct page *page, int order) { }
    #endif
    #ifndef HAVE_ARCH_ALLOC_PAGE
    static inline void arch_alloc_page(struct page *page, int order) { }
    #endif
    
    struct page *
    __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order, int preferred_nid,
    							nodemask_t *nodemask);
    
    static inline struct page *
    __alloc_pages(gfp_t gfp_mask, unsigned int order, int preferred_nid)
    {
    	return __alloc_pages_nodemask(gfp_mask, order, preferred_nid, NULL);
    }
    
    /*
     * Allocate pages, preferring the node given as nid. The node must be valid and
     * online. For more general interface, see alloc_pages_node().
     */
    static inline struct page *
    __alloc_pages_node(int nid, gfp_t gfp_mask, unsigned int order)
    {
    	VM_BUG_ON(nid < 0 || nid >= MAX_NUMNODES);
    	VM_WARN_ON(!node_online(nid));
    
    	return __alloc_pages(gfp_mask, order, nid);
    }
    
    /*
     * Allocate pages, preferring the node given as nid. When nid == NUMA_NO_NODE,
     * prefer the current CPU's closest node. Otherwise node must be valid and
     * online.
     */
    static inline struct page *alloc_pages_node(int nid, gfp_t gfp_mask,
    						unsigned int order)
    {
    	if (nid == NUMA_NO_NODE)
    		nid = numa_mem_id();
    
    	return __alloc_pages_node(nid, gfp_mask, order);
    }
    
    #ifdef CONFIG_NUMA
    extern struct page *alloc_pages_current(gfp_t gfp_mask, unsigned order);
    
    static inline struct page *
    alloc_pages(gfp_t gfp_mask, unsigned int order)
    {
    	return alloc_pages_current(gfp_mask, order);
    }
    extern struct page *alloc_pages_vma(gfp_t gfp_mask, int order,
    			struct vm_area_struct *vma, unsigned long addr,
    			int node, bool hugepage);
    #define alloc_hugepage_vma(gfp_mask, vma, addr, order)	\
    	alloc_pages_vma(gfp_mask, order, vma, addr, numa_node_id(), true)
    #else
    #define alloc_pages(gfp_mask, order) \
    		alloc_pages_node(numa_node_id(), gfp_mask, order)
    #define alloc_pages_vma(gfp_mask, order, vma, addr, node, false)\
    	alloc_pages(gfp_mask, order)
    #define alloc_hugepage_vma(gfp_mask, vma, addr, order)	\
    	alloc_pages(gfp_mask, order)
    #endif
    #define alloc_page(gfp_mask) alloc_pages(gfp_mask, 0)
    #define alloc_page_vma(gfp_mask, vma, addr)			\
    	alloc_pages_vma(gfp_mask, 0, vma, addr, numa_node_id(), false)
    #define alloc_page_vma_node(gfp_mask, vma, addr, node)		\
    	alloc_pages_vma(gfp_mask, 0, vma, addr, node, false)
    
    extern unsigned long __get_free_pages(gfp_t gfp_mask, unsigned int order);
    extern unsigned long get_zeroed_page(gfp_t gfp_mask);
    
    void *alloc_pages_exact(size_t size, gfp_t gfp_mask);
    void free_pages_exact(void *virt, size_t size);
    void * __meminit alloc_pages_exact_nid(int nid, size_t size, gfp_t gfp_mask);
    
    #define __get_free_page(gfp_mask) \
    		__get_free_pages((gfp_mask), 0)
    
    #define __get_dma_pages(gfp_mask, order) \
    		__get_free_pages((gfp_mask) | GFP_DMA, (order))
    
    extern void __free_pages(struct page *page, unsigned int order);
    extern void free_pages(unsigned long addr, unsigned int order);
    extern void free_hot_cold_page(struct page *page, bool cold);
    extern void free_hot_cold_page_list(struct list_head *list, bool cold);
    
    struct page_frag_cache;
    extern void __page_frag_cache_drain(struct page *page, unsigned int count);
    extern void *page_frag_alloc(struct page_frag_cache *nc,
    			     unsigned int fragsz, gfp_t gfp_mask);
    extern void page_frag_free(void *addr);
    
    #define __free_page(page) __free_pages((page), 0)
    #define free_page(addr) free_pages((addr), 0)
    
    void page_alloc_init(void);
    void drain_zone_pages(struct zone *zone, struct per_cpu_pages *pcp);
    void drain_all_pages(struct zone *zone);
    void drain_local_pages(struct zone *zone);
    
    void page_alloc_init_late(void);
    
    /*
     * gfp_allowed_mask is set to GFP_BOOT_MASK during early boot to restrict what
     * GFP flags are used before interrupts are enabled. Once interrupts are
     * enabled, it is set to __GFP_BITS_MASK while the system is running. During
     * hibernation, it is used by PM to avoid I/O during memory allocation while
     * devices are suspended.
     */
    extern gfp_t gfp_allowed_mask;
    
    /* Returns true if the gfp_mask allows use of ALLOC_NO_WATERMARK */
    bool gfp_pfmemalloc_allowed(gfp_t gfp_mask);
    
    extern void pm_restrict_gfp_mask(void);
    extern void pm_restore_gfp_mask(void);
    
    #ifdef CONFIG_PM_SLEEP
    extern bool pm_suspended_storage(void);
    #else
    static inline bool pm_suspended_storage(void)
    {
    	return false;
    }
    #endif /* CONFIG_PM_SLEEP */
    
    #if (defined(CONFIG_MEMORY_ISOLATION) && defined(CONFIG_COMPACTION)) || defined(CONFIG_CMA)
    /* The below functions must be run on a range from a single zone. */
    extern int alloc_contig_range(unsigned long start, unsigned long end,
    			      unsigned migratetype, gfp_t gfp_mask);
    extern void free_contig_range(unsigned long pfn, unsigned nr_pages);
    #endif
    
    #ifdef CONFIG_CMA
    /* CMA stuff */
    extern void init_cma_reserved_pageblock(struct page *page);
    #endif
    
    #endif /* __LINUX_GFP_H */