From: Alexey Dobriyan <[email protected]>
/*
* cpu_partial determined the maximum number of objects
* kept in the per cpu partial lists of a processor.
*/
Can't be negative.
I hit a real issue that it will result in a large number of memory leak.
Because Freeing slabs are in interrupt context. So it can trigger this issue.
put_cpu_partial can be interrupted more than once.
due to a union struct of lru and pobjects in struct page, when other core handles
page->lru list, for eaxmple, remove_partial in freeing slab code flow, It will
result in pobjects being a negative value(0xdead0000). Therefore, a large number
of slabs will be added to per_cpu partial list.
I had posted the issue to community before. The detailed issue description is as follows.
Link: https://www.spinics.net/lists/kernel/msg2870979.html
After applying the patch, The issue is fixed. So the patch is a effective bugfix.
It should go into stable.
Signed-off-by: Alexey Dobriyan <[email protected]>
Acked-by: Christoph Lameter <[email protected]>
Cc: Pekka Enberg <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Cc: [email protected]
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Signed-off-by: zhong jiang <[email protected]>
---
include/linux/slub_def.h | 3 ++-
mm/slub.c | 6 +++---
2 files changed, 5 insertions(+), 4 deletions(-)
diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h
index 3388511..9b681f2 100644
--- a/include/linux/slub_def.h
+++ b/include/linux/slub_def.h
@@ -67,7 +67,8 @@ struct kmem_cache {
int size; /* The size of an object including meta data */
int object_size; /* The size of an object without meta data */
int offset; /* Free pointer offset. */
- int cpu_partial; /* Number of per cpu partial objects to keep around */
+ /* Number of per cpu partial objects to keep around */
+ unsigned int cpu_partial;
struct kmem_cache_order_objects oo;
/* Allocation and freeing of slabs */
diff --git a/mm/slub.c b/mm/slub.c
index 2284c43..c33b0e1 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1661,7 +1661,7 @@ static void *get_partial_node(struct kmem_cache *s, struct kmem_cache_node *n,
{
struct page *page, *page2;
void *object = NULL;
- int available = 0;
+ unsigned int available = 0;
int objects;
/*
@@ -4674,10 +4674,10 @@ static ssize_t cpu_partial_show(struct kmem_cache *s, char *buf)
static ssize_t cpu_partial_store(struct kmem_cache *s, const char *buf,
size_t length)
{
- unsigned long objects;
+ unsigned int objects;
int err;
- err = kstrtoul(buf, 10, &objects);
+ err = kstrtouint(buf, 10, &objects);
if (err)
return err;
if (objects && !kmem_cache_has_cpu_partial(s))
--
1.7.12.4
On Thu, 27 Sep 2018, zhong jiang wrote:
> From: Alexey Dobriyan <[email protected]>
>
> /*
> * cpu_partial determined the maximum number of objects
> * kept in the per cpu partial lists of a processor.
> */
>
> Can't be negative.
True.
> I hit a real issue that it will result in a large number of memory leak.
> Because Freeing slabs are in interrupt context. So it can trigger this issue.
> put_cpu_partial can be interrupted more than once.
> due to a union struct of lru and pobjects in struct page, when other core handles
> page->lru list, for eaxmple, remove_partial in freeing slab code flow, It will
> result in pobjects being a negative value(0xdead0000). Therefore, a large number
> of slabs will be added to per_cpu partial list.
That sounds like it needs more investigation. Concurrent use of page
fields for other purposes can cause serious bugs.
>
> I had posted the issue to community before. The detailed issue description is as follows.
I did not see it. Please make sure to CC the maintainers.
On Thu, Sep 27, 2018 at 10:43:40PM +0800, zhong jiang wrote:
> From: Alexey Dobriyan <[email protected]>
>
> /*
> * cpu_partial determined the maximum number of objects
> * kept in the per cpu partial lists of a processor.
> */
>
> Can't be negative.
>
> I hit a real issue that it will result in a large number of memory leak.
> Because Freeing slabs are in interrupt context. So it can trigger this issue.
> put_cpu_partial can be interrupted more than once.
> due to a union struct of lru and pobjects in struct page, when other core handles
> page->lru list, for eaxmple, remove_partial in freeing slab code flow, It will
> result in pobjects being a negative value(0xdead0000). Therefore, a large number
> of slabs will be added to per_cpu partial list.
>
> I had posted the issue to community before. The detailed issue description is as follows.
>
> Link: https://www.spinics.net/lists/kernel/msg2870979.html
>
> After applying the patch, The issue is fixed. So the patch is a effective bugfix.
> It should go into stable.
<formletter>
This is not the correct way to submit patches for inclusion in the
stable kernel tree. Please read:
https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.
</formletter>
On 2018/9/27 23:46, Greg KH wrote:
> On Thu, Sep 27, 2018 at 10:43:40PM +0800, zhong jiang wrote:
>> From: Alexey Dobriyan <[email protected]>
>>
>> /*
>> * cpu_partial determined the maximum number of objects
>> * kept in the per cpu partial lists of a processor.
>> */
>>
>> Can't be negative.
>>
>> I hit a real issue that it will result in a large number of memory leak.
>> Because Freeing slabs are in interrupt context. So it can trigger this issue.
>> put_cpu_partial can be interrupted more than once.
>> due to a union struct of lru and pobjects in struct page, when other core handles
>> page->lru list, for eaxmple, remove_partial in freeing slab code flow, It will
>> result in pobjects being a negative value(0xdead0000). Therefore, a large number
>> of slabs will be added to per_cpu partial list.
>>
>> I had posted the issue to community before. The detailed issue description is as follows.
>>
>> Link: https://www.spinics.net/lists/kernel/msg2870979.html
>>
>> After applying the patch, The issue is fixed. So the patch is a effective bugfix.
>> It should go into stable.
> <formletter>
>
> This is not the correct way to submit patches for inclusion in the
> stable kernel tree. Please read:
> https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
> for how to do this properly.
>
> </formletter>
Will resend with proper format.
Thanks,
zhong jiang