Commit 0a71649c authored Mar 17, 2016 by Naoya Horiguchi Committed by Linus Torvalds Mar 17, 2016

/proc/kpageflags: return KPF_SLAB for slab tail pages



Currently /proc/kpageflags returns just KPF_COMPOUND_TAIL for slab tail
pages, which is inconvenient when grasping how slab pages are
distributed (userspace always needs to check which kind of tail pages by
itself).  This patch sets KPF_SLAB for such pages.

With this patch:

  $ grep Slab /proc/meminfo ; tools/vm/page-types -b slab
  Slab:              64880 kB
               flags      page-count       MB  symbolic-flags                     long-symbolic-flags
  0x0000000000000080           16220       63  _______S__________________________________ slab
               total           16220       63

16220 pages equals to 64880 kB, so returned result is consistent with the
global counter.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Reviewed-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 832fc1de

fs/proc/page.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -160,6 +160,8 @@ u64 stable_page_flags(struct page *page)
		u \|= kpf_copy_bit(k, KPF_LOCKED, PG_locked);

		u \|= kpf_copy_bit(k, KPF_SLAB, PG_slab);
		if (PageTail(page) && PageSlab(compound_head(page)))
		u \|= 1 << KPF_SLAB;

		u \|= kpf_copy_bit(k, KPF_ERROR, PG_error);
		u \|= kpf_copy_bit(k, KPF_DIRTY, PG_dirty);

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