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From: David Rientjes <rientjes@google.com>
To: Roman Gushchin <guro@fb.com>
Cc: linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
	Michal Hocko <mhocko@kernel.org>,
	Johannes Weiner <hannes@cmpxchg.org>,
	linux-kernel@vger.kernel.org, kernel-team@fb.com,
	Vladimir Davydov <vdavydov.dev@gmail.com>,
	Daniel Jordan <daniel.m.jordan@oracle.com>
Subject: Re: [PATCH v2] mm: slab: make page_cgroup_ino() to recognize non-compound slab pages properly
Date: Thu, 31 Oct 2019 11:16:07 -0700 (PDT)	[thread overview]
Message-ID: <alpine.DEB.2.21.1910311115540.226869@chino.kir.corp.google.com> (raw)
In-Reply-To: <20191031012151.2722280-1-guro@fb.com>

On Wed, 30 Oct 2019, Roman Gushchin wrote:

> page_cgroup_ino() doesn't return a valid memcg pointer for non-compound
> slab pages, because it depends on PgHead AND PgSlab flags to be set
> to determine the memory cgroup from the kmem_cache.
> It's correct for compound pages, but not for generic small pages. Those
> don't have PgHead set, so it ends up returning zero.
> 
> Fix this by replacing the condition to PageSlab() && !PageTail().
> 
> Before this patch:
> [root@localhost ~]# ./page-types -c /sys/fs/cgroup/user.slice/user-0.slice/user@0.service/ | grep slab
> 0x0000000000000080	        38        0  _______S___________________________________	slab
> 
> After this patch:
> [root@localhost ~]# ./page-types -c /sys/fs/cgroup/user.slice/user-0.slice/user@0.service/ | grep slab
> 0x0000000000000080	       147        0  _______S___________________________________	slab
> 
> Fixes: 4d96ba353075 ("mm: memcg/slab: stop setting page->mem_cgroup pointer for slab pages")
> Signed-off-by: Roman Gushchin <guro@fb.com>
> Reviewed-by: Shakeel Butt <shakeelb@google.com>
> Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
> Cc: Daniel Jordan <daniel.m.jordan@oracle.com>

Acked-by: David Rientjes <rientjes@google.com>

      parent reply	other threads:[~2019-10-31 18:16 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-31  1:21 [PATCH v2] mm: slab: make page_cgroup_ino() to recognize non-compound slab pages properly Roman Gushchin
2019-10-31  4:16 ` Andrew Morton
2019-10-31  9:38   ` Naoya Horiguchi
2019-10-31 15:49     ` Roman Gushchin
2019-10-31 18:16 ` David Rientjes [this message]

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