On Sun, Sep 30, 2018 at 06:28:21PM +0800, zhong jiang wrote:
> From: Alexey Dobriyan <adobri...@gmail.com>
>
> [ Upstream commit e5d9998f3e09359b372a037a6ac55ba235d95d57 ]
>
> /*
> * 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.
> Becuase 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.
>
> 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.
>
> Link: http://lkml.kernel.org/r/20180305200730.15812-15-adobri...@gmail.com
> Signed-off-by: Alexey Dobriyan <adobri...@gmail.com>
> Acked-by: Christoph Lameter <c...@linux.com>
Hang on. Christoph acked the _original_ patch going into upstream.
When he reviewed this patch for _stable_ last week, he asked for more
investigation. Including this patch in stable is misleading.
> Cc: Pekka Enberg <penb...@kernel.org>
> Cc: David Rientjes <rient...@google.com>
> Cc: Joonsoo Kim <iamjoonsoo....@lge.com>
> Cc: <sta...@vger.kernel.org> # 4.4.x
> Signed-off-by: Andrew Morton <a...@linux-foundation.org>
> Signed-off-by: Linus Torvalds <torva...@linux-foundation.org>
> Signed-off-by: zhong jiang <zhongji...@huawei.com>
> ---
> 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
>
