Re: [PATCH -mm] slub: kmem_cache_shrink: init discard list after freeing slabs

[David Rientjes]

On Wed, 11 Feb 2015, Vladimir Davydov wrote:

> Currently, the discard list is only initialized at the beginning of the
> function. As a result, if there are > 1 nodes, we can get use-after-free
> while processing the second or higher node:
> 
>     WARNING: CPU: 60 PID: 1 at lib/list_debug.c:29 __list_add+0x3c/0xa9()
>     list_add corruption. next->prev should be prev (ffff881ff0a6bb98), but was ffffea007ff57020. (next=ffffea007fbf7320).
>     Modules linked in:
>     CPU: 60 PID: 1 Comm: swapper/0 Not tainted 3.19.0-rc7-next-20150203-gb50cadf #2178
>     Hardware name: Intel Corporation BRICKLAND/BRICKLAND, BIOS BIVTSDP1.86B.0038.R02.1307231126 07/23/2013
>      0000000000000009 ffff881ff0a6ba88 ffffffff81c2e096 ffffffff810e2d03
>      ffff881ff0a6bad8 ffff881ff0a6bac8 ffffffff8108b320 ffff881ff0a6bb18
>      ffffffff8154bbc7 ffff881ff0a6bb98 ffffea007fbf7320 ffffea00ffc3c220
>     Call Trace:
>      [<ffffffff81c2e096>] dump_stack+0x4c/0x65
>      [<ffffffff810e2d03>] ? console_unlock+0x398/0x3c7
>      [<ffffffff8108b320>] warn_slowpath_common+0xa1/0xbb
>      [<ffffffff8154bbc7>] ? __list_add+0x3c/0xa9
>      [<ffffffff8108b380>] warn_slowpath_fmt+0x46/0x48
>      [<ffffffff8154bbc7>] __list_add+0x3c/0xa9
>      [<ffffffff811bf5aa>] __kmem_cache_shrink+0x12b/0x24c
>      [<ffffffff81190ca9>] kmem_cache_shrink+0x26/0x38
>      [<ffffffff815848b4>] acpi_os_purge_cache+0xe/0x12
>      [<ffffffff815c6424>] acpi_purge_cached_objects+0x32/0x7a
>      [<ffffffff825f70f1>] acpi_initialize_objects+0x17e/0x1ae
>      [<ffffffff825f5177>] ? acpi_sleep_proc_init+0x2a/0x2a
>      [<ffffffff825f5209>] acpi_init+0x92/0x25e
>      [<ffffffff810002bd>] ? do_one_initcall+0x90/0x17f
>      [<ffffffff811bdfcd>] ? kfree+0x1fc/0x2d5
>      [<ffffffff825f5177>] ? acpi_sleep_proc_init+0x2a/0x2a
>      [<ffffffff8100031a>] do_one_initcall+0xed/0x17f
>      [<ffffffff825ae0e2>] kernel_init_freeable+0x1f0/0x278
>      [<ffffffff81c1f31a>] ? rest_init+0x13e/0x13e
>      [<ffffffff81c1f328>] kernel_init+0xe/0xda
>      [<ffffffff81c3ca7c>] ret_from_fork+0x7c/0xb0
>      [<ffffffff81c1f31a>] ? rest_init+0x13e/0x13e
> 
> Fix this by initializing the discard list at each iteration of the
> for_each_kmem_cache_node loop. Also, move promote lists initialization
> to the beginning of the loop to conform.
> 
> fixes: slub-never-fail-to-shrink-cache

8f44a586ac86 ("slub: never fail to shrink cache")

> Signed-off-by: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>
> Reported-by: Huang Ying <ying.huang@xxxxxxxxx>
> Cc: Christoph Lameter <cl@xxxxxxxxx>
> Cc: Pekka Enberg <penberg@xxxxxxxxxx>
> Cc: David Rientjes <rientjes@xxxxxxxxxx>
> Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>

Acked-by: David Rientjes <rientjes@xxxxxxxxxx>
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