Commit 8afb1474 authored Sep 10, 2013 by Li Zefan Committed by Pekka Enberg Dec 29, 2013

slub: Fix calculation of cpu slabs



  /sys/kernel/slab/:t-0000048 # cat cpu_slabs
  231 N0=16 N1=215
  /sys/kernel/slab/:t-0000048 # cat slabs
  145 N0=36 N1=109

See, the number of slabs is smaller than that of cpu slabs.

The bug was introduced by commit 49e22585
("slub: per cpu cache for partial pages").

We should use page->pages instead of page->pobjects when calculating
the number of cpu partial slabs. This also fixes the mapping of slabs
and nodes.

As there's no variable storing the number of total/active objects in
cpu partial slabs, and we don't have user interfaces requiring those
statistics, I just add WARN_ON for those cases.

Cc: <stable@vger.kernel.org> # 3.2+
Acked-by: Christoph Lameter <cl@linux.com>
Reviewed-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>

parent e1168c2c

mm/slub.c

+7 −1

Original line number	Diff line number	Diff line
		@@ -4299,7 +4299,13 @@ static ssize_t show_slab_objects(struct kmem_cache *s,

		page = ACCESS_ONCE(c->partial);
		if (page) {
		x = page->pobjects;
		node = page_to_nid(page);
		if (flags & SO_TOTAL)
		WARN_ON_ONCE(1);
		else if (flags & SO_OBJECTS)
		WARN_ON_ONCE(1);
		else
		x = page->pages;
		total += x;
		nodes[node] += x;
		}