On 2013/12/27 17:46, Wanpeng Li wrote:
> SLUB per cpu partial cache is a list of slab caches to accelerate objects
> allocation. However, current codes just accumulate the objects number of
> the first slab cache of per cpu partial cache instead of traverse the whole
> list.
>
> Signed-off-by: Wanpeng Li <liwanp@xxxxxxxxxxxxxxxxxx>
> ---
> mm/slub.c | 32 +++++++++++++++++++++++---------
> 1 files changed, 23 insertions(+), 9 deletions(-)
>
> diff --git a/mm/slub.c b/mm/slub.c
> index 545a170..799bfdc 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -4280,7 +4280,7 @@ static ssize_t show_slab_objects(struct kmem_cache *s,
> struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab,
> cpu);
> int node;
> - struct page *page;
> + struct page *page, *p;
>
> page = ACCESS_ONCE(c->page);
> if (!page)
> @@ -4298,8 +4298,9 @@ static ssize_t show_slab_objects(struct kmem_cache *s,
> nodes[node] += x;
>
> page = ACCESS_ONCE(c->partial);
> - if (page) {
> - x = page->pobjects;
> + while ((p = page)) {
> + page = p->next;
> + x = p->pobjects;
> total += x;
> nodes[node] += x;
> }
Can we apply this patch first? It was sent month ago, but Pekka was not responsive.
=============================
[PATCH] 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 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>
Acked-by: Christoph Lameter <cl@xxxxxxxxx>
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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