On Tue, Sep 10, 2013 at 11:43:37AM +0800, Li Zefan wrote:
> /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 49e2258586b423684f03c278149ab46d8f8b6700
>("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@xxxxxxxxxxxxxxx> # 3.2+
>Signed-off-by: Li Zefan <lizefan@xxxxxxxxxx>
Reviewed-by: Wanpeng Li <liwanp@xxxxxxxxxxxxxxxxxx>
>---
> mm/slub.c | 8 +++++++-
> 1 file changed, 7 insertions(+), 1 deletion(-)
>
>diff --git a/mm/slub.c b/mm/slub.c
>index e3ba1f2..6ea461d 100644
>--- a/mm/slub.c
>+++ b/mm/slub.c
>@@ -4300,7 +4300,13 @@ 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;
> }
>--
>1.8.0.2
>
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