All of lore.kernel.org
 help / color / mirror / Atom feed
From: Johannes Weiner <hannes@cmpxchg.org>
To: Michal Hocko <mhocko@kernel.org>
Cc: "Andrew Morton" <akpm@linux-foundation.org>,
	"Vladimir Davydov" <vdavydov.dev@gmail.com>,
	"Marek Marczykowski-Górecki" <marmarek@mimuw.edu.pl>,
	"Balbir Singh" <bsingharora@gmail.com>,
	linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] mm: workingset: fix NULL ptr in count_shadow_nodes
Date: Thu, 1 Dec 2016 16:07:15 -0500	[thread overview]
Message-ID: <20161201210715.GA21302@cmpxchg.org> (raw)
In-Reply-To: <20161201132156.21450-1-mhocko@kernel.org>

On Thu, Dec 01, 2016 at 02:21:56PM +0100, Michal Hocko wrote:
> From: Michal Hocko <mhocko@suse.com>
> 
> 0a6b76dd23fa ("mm: workingset: make shadow node shrinker memcg aware")
> has made the workingset shadow nodes shrinker memcg aware. The
> implementation is not correct though because memcg_kmem_enabled() might
> become true while we are doing a global reclaim when the sc->memcg might
> be NULL which is exactly what Marek has seen:

[...]

> This patch fixes the issue by checking sc->memcg rather than memcg_kmem_enabled()
> which is sufficient because shrink_slab makes sure that only memcg aware shrinkers
> will get non-NULL memcgs and only if memcg_kmem_enabled is true.
> 
> Fixes: 0a6b76dd23fa ("mm: workingset: make shadow node shrinker memcg aware")
> Reported-and-tested-by: Marek Marczykowski-Górecki <marmarek@mimuw.edu.pl>
> Cc: stable@vger.kernel.org # 4.6+
> Signed-off-by: Michal Hocko <mhocko@suse.com>

Acked-by: Johannes Weiner <hannes@cmpxchg.org>

Thanks Michal

WARNING: multiple messages have this Message-ID (diff)
From: Johannes Weiner <hannes@cmpxchg.org>
To: Michal Hocko <mhocko@kernel.org>
Cc: "Andrew Morton" <akpm@linux-foundation.org>,
	"Vladimir Davydov" <vdavydov.dev@gmail.com>,
	"Marek Marczykowski-Górecki" <marmarek@mimuw.edu.pl>,
	"Balbir Singh" <bsingharora@gmail.com>,
	linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] mm: workingset: fix NULL ptr in count_shadow_nodes
Date: Thu, 1 Dec 2016 16:07:15 -0500	[thread overview]
Message-ID: <20161201210715.GA21302@cmpxchg.org> (raw)
In-Reply-To: <20161201132156.21450-1-mhocko@kernel.org>

On Thu, Dec 01, 2016 at 02:21:56PM +0100, Michal Hocko wrote:
> From: Michal Hocko <mhocko@suse.com>
> 
> 0a6b76dd23fa ("mm: workingset: make shadow node shrinker memcg aware")
> has made the workingset shadow nodes shrinker memcg aware. The
> implementation is not correct though because memcg_kmem_enabled() might
> become true while we are doing a global reclaim when the sc->memcg might
> be NULL which is exactly what Marek has seen:

[...]

> This patch fixes the issue by checking sc->memcg rather than memcg_kmem_enabled()
> which is sufficient because shrink_slab makes sure that only memcg aware shrinkers
> will get non-NULL memcgs and only if memcg_kmem_enabled is true.
> 
> Fixes: 0a6b76dd23fa ("mm: workingset: make shadow node shrinker memcg aware")
> Reported-and-tested-by: Marek Marczykowski-Gorecki <marmarek@mimuw.edu.pl>
> Cc: stable@vger.kernel.org # 4.6+
> Signed-off-by: Michal Hocko <mhocko@suse.com>

Acked-by: Johannes Weiner <hannes@cmpxchg.org>

Thanks Michal

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

  parent reply	other threads:[~2016-12-01 21:07 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-12-01 13:21 [PATCH] mm: workingset: fix NULL ptr in count_shadow_nodes Michal Hocko
2016-12-01 13:21 ` Michal Hocko
2016-12-01 13:32 ` Vladimir Davydov
2016-12-01 13:32   ` Vladimir Davydov
2016-12-01 21:07 ` Johannes Weiner [this message]
2016-12-01 21:07   ` Johannes Weiner
2016-12-01 21:24 ` Balbir Singh
2016-12-01 21:24   ` Balbir Singh

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20161201210715.GA21302@cmpxchg.org \
    --to=hannes@cmpxchg.org \
    --cc=akpm@linux-foundation.org \
    --cc=bsingharora@gmail.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=marmarek@mimuw.edu.pl \
    --cc=mhocko@kernel.org \
    --cc=vdavydov.dev@gmail.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.