* [PATCH] slub: Fix calculation of cpu slabs
@ 2013-09-10 3:43 Li Zefan
2013-09-10 21:06 ` Christoph Lameter
2013-10-05 7:48 ` Wanpeng Li
0 siblings, 2 replies; 5+ messages in thread
From: Li Zefan @ 2013-09-10 3:43 UTC (permalink / raw)
To: Christoph Lameter; +Cc: Pekka Enberg, LKML, linux-mm@kvack.org
/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@vger.kernel.org> # 3.2+
Signed-off-by: Li Zefan <lizefan@huawei.com>
---
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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^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [PATCH] slub: Fix calculation of cpu slabs
2013-09-10 3:43 [PATCH] slub: Fix calculation of cpu slabs Li Zefan
@ 2013-09-10 21:06 ` Christoph Lameter
2013-10-14 7:27 ` Li Zefan
2013-10-05 7:48 ` Wanpeng Li
1 sibling, 1 reply; 5+ messages in thread
From: Christoph Lameter @ 2013-09-10 21:06 UTC (permalink / raw)
To: Li Zefan; +Cc: Pekka Enberg, LKML, linux-mm@kvack.org
On Tue, 10 Sep 2013, Li Zefan wrote:
> 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.
True.
> 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.
Well that is not strictly required but it does not hurt either.
Acked-by: Christoph Lameter <cl@linux.com>
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^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] slub: Fix calculation of cpu slabs
2013-09-10 21:06 ` Christoph Lameter
@ 2013-10-14 7:27 ` Li Zefan
0 siblings, 0 replies; 5+ messages in thread
From: Li Zefan @ 2013-10-14 7:27 UTC (permalink / raw)
To: Pekka Enberg; +Cc: Christoph Lameter, LKML, linux-mm@kvack.org
Hi Pekka,
could you pick up this patch?
On 2013/9/11 5:06, Christoph Lameter wrote:
> On Tue, 10 Sep 2013, Li Zefan wrote:
>
>> 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.
>
> True.
>
>> 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.
>
>
> Well that is not strictly required but it does not hurt either.
>
> Acked-by: Christoph Lameter <cl@linux.com>
>
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^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] slub: Fix calculation of cpu slabs
2013-09-10 3:43 [PATCH] slub: Fix calculation of cpu slabs Li Zefan
2013-09-10 21:06 ` Christoph Lameter
@ 2013-10-05 7:48 ` Wanpeng Li
2013-12-29 11:45 ` Pekka Enberg
1 sibling, 1 reply; 5+ messages in thread
From: Wanpeng Li @ 2013-10-05 7:48 UTC (permalink / raw)
To: Li Zefan; +Cc: Christoph Lameter, Pekka Enberg, LKML, linux-mm@kvack.org
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@vger.kernel.org> # 3.2+
>Signed-off-by: Li Zefan <lizefan@huawei.com>
Reviewed-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
>---
> 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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^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] slub: Fix calculation of cpu slabs
2013-10-05 7:48 ` Wanpeng Li
@ 2013-12-29 11:45 ` Pekka Enberg
0 siblings, 0 replies; 5+ messages in thread
From: Pekka Enberg @ 2013-12-29 11:45 UTC (permalink / raw)
To: Wanpeng Li; +Cc: Li Zefan, Christoph Lameter, LKML, linux-mm@kvack.org
On Sat, Oct 5, 2013 at 10:48 AM, Wanpeng Li <liwanp@linux.vnet.ibm.com> wrote:
> 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@vger.kernel.org> # 3.2+
>>Signed-off-by: Li Zefan <lizefan@huawei.com>
>
> Reviewed-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Applied and sorry for the slow response!
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^ permalink raw reply [flat|nested] 5+ messages in thread
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2013-09-10 3:43 [PATCH] slub: Fix calculation of cpu slabs Li Zefan
2013-09-10 21:06 ` Christoph Lameter
2013-10-14 7:27 ` Li Zefan
2013-10-05 7:48 ` Wanpeng Li
2013-12-29 11:45 ` Pekka Enberg
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