From c9e0d39126af9e338495b719e9d565ca9ebcd4c5 Mon Sep 17 00:00:00 2001
From: Dave Jones <davej@codemonkey.org.uk>
Date: Mon, 11 Jan 2016 12:04:28 -0500
Subject: [PATCH] x86/mm/pat: Make split_page_count() check for empty levels to
fix /proc/meminfo output
In CONFIG_PAGEALLOC_DEBUG=y builds, we disable 2M pages.
Unfortunatly when we split up mappings during boot,
split_page_count() doesn't take this into account, and
starts decrementing an empty direct_pages_count[] level.
This results in /proc/meminfo showing crazy things like:
DirectMap2M: 18446744073709543424 kB
Signed-off-by: Dave Jones <davej@codemonkey.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luis R. Rodriguez <mcgrof@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Toshi Kani <toshi.kani@hp.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/mm/pageattr.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index 6000ad7f560c..fc6a4c8f6e2a 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -66,6 +66,9 @@ void update_page_count(int level, unsigned long pages)
static void split_page_count(int level)
{
+ if (direct_pages_count[level] == 0)
+ return;
+
direct_pages_count[level]--;
direct_pages_count[level - 1] += PTRS_PER_PTE;
}
--
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