Commit c9e0d391 authored Jan 11, 2016 by Dave Jones Committed by Ingo Molnar Jan 12, 2016

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>

parent c0c57019

arch/x86/mm/pageattr.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -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;
		}