Re: kmemleaks reports a lot of cases around memcg_create_kmem_cache

[Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>]

On Sun, Jul 02, 2017 at 09:50:17PM +0300, Vladimir Davydov wrote:
> From: Vladimir Davydov <vdavydov.dev-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> Subject: [PATCH] slub: fix per memcg cache leak on css offline
> 
> To avoid a possible deadlock, sysfs_slab_remove() schedules an
> asynchronous work to delete sysfs entries corresponding to the kmem
> cache. To ensure the cache isn't freed before the work function is
> called, it takes a reference to the cache kobject. The reference is
> supposed to be released by the work function. However, the work function
> (sysfs_slab_remove_workfn()) does nothing in case the cache sysfs entry
> has already been deleted, leaking the kobject and the corresponding
> cache. This may happen on a per memcg cache destruction, because sysfs
> entries of a per memcg cache are deleted on memcg offline if the cache
> is empty (see __kmemcg_cache_deactivate()).
...
> Reported-by: Andrei Vagin <avagin-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> Signed-off-by: Vladimir Davydov <vdavydov.dev-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> Fixes: 3b7b314053d02 ("slub: make sysfs file removal asynchronous")

Oops,

Acked-by: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>

Thanks.

-- 
tejun