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From: Vladimir Davydov <vdavydov.dev@gmail.com>
To: Johannes Weiner <hannes@cmpxchg.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Tejun Heo <tj@kernel.org>,
	"David S. Miller" <davem@davemloft.net>,
	Michal Hocko <mhocko@suse.cz>,
	linux-mm@kvack.org, cgroups@vger.kernel.org,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	kernel-team@fb.com
Subject: Re: [PATCH 1/3] mm: memcontrol: make per-cpu charge cache IRQ-safe for socket accounting
Date: Mon, 19 Sep 2016 18:35:45 +0300	[thread overview]
Message-ID: <20160919153545.GF1989@esperanza> (raw)
In-Reply-To: <20160914194846.11153-1-hannes@cmpxchg.org>

On Wed, Sep 14, 2016 at 03:48:44PM -0400, Johannes Weiner wrote:
> From: Johannes Weiner <jweiner@fb.com>
> 
> During cgroup2 rollout into production, we started encountering css
> refcount underflows and css access crashes in the memory controller.
> Splitting the heavily shared css reference counter into logical users
> narrowed the imbalance down to the cgroup2 socket memory accounting.
> 
> The problem turns out to be the per-cpu charge cache. Cgroup1 had a
> separate socket counter, but the new cgroup2 socket accounting goes
> through the common charge path that uses a shared per-cpu cache for
> all memory that is being tracked. Those caches are safe against
> scheduling preemption, but not against interrupts - such as the newly
> added packet receive path. When cache draining is interrupted by
> network RX taking pages out of the cache, the resuming drain operation
> will put references of in-use pages, thus causing the imbalance.
> 
> Disable IRQs during all per-cpu charge cache operations.
> 
> Fixes: f7e1cb6ec51b ("mm: memcontrol: account socket memory in unified hierarchy memory controller")
> Cc: <stable@vger.kernel.org> # 4.5+
> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>

Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>

WARNING: multiple messages have this Message-ID (diff)
From: Vladimir Davydov <vdavydov.dev@gmail.com>
To: Johannes Weiner <hannes@cmpxchg.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Tejun Heo <tj@kernel.org>,
	"David S. Miller" <davem@davemloft.net>,
	Michal Hocko <mhocko@suse.cz>,
	linux-mm@kvack.org, cgroups@vger.kernel.org,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	kernel-team@fb.com
Subject: Re: [PATCH 1/3] mm: memcontrol: make per-cpu charge cache IRQ-safe for socket accounting
Date: Mon, 19 Sep 2016 18:35:45 +0300	[thread overview]
Message-ID: <20160919153545.GF1989@esperanza> (raw)
In-Reply-To: <20160914194846.11153-1-hannes@cmpxchg.org>

On Wed, Sep 14, 2016 at 03:48:44PM -0400, Johannes Weiner wrote:
> From: Johannes Weiner <jweiner@fb.com>
> 
> During cgroup2 rollout into production, we started encountering css
> refcount underflows and css access crashes in the memory controller.
> Splitting the heavily shared css reference counter into logical users
> narrowed the imbalance down to the cgroup2 socket memory accounting.
> 
> The problem turns out to be the per-cpu charge cache. Cgroup1 had a
> separate socket counter, but the new cgroup2 socket accounting goes
> through the common charge path that uses a shared per-cpu cache for
> all memory that is being tracked. Those caches are safe against
> scheduling preemption, but not against interrupts - such as the newly
> added packet receive path. When cache draining is interrupted by
> network RX taking pages out of the cache, the resuming drain operation
> will put references of in-use pages, thus causing the imbalance.
> 
> Disable IRQs during all per-cpu charge cache operations.
> 
> Fixes: f7e1cb6ec51b ("mm: memcontrol: account socket memory in unified hierarchy memory controller")
> Cc: <stable@vger.kernel.org> # 4.5+
> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>

Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>

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  parent reply	other threads:[~2016-09-19 15:35 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-09-14 19:48 [PATCH 1/3] mm: memcontrol: make per-cpu charge cache IRQ-safe for socket accounting Johannes Weiner
2016-09-14 19:48 ` Johannes Weiner
2016-09-14 19:48 ` [PATCH 2/3] cgroup: duplicate cgroup reference when cloning sockets Johannes Weiner
2016-09-14 19:48   ` Johannes Weiner
2016-09-19 12:03   ` Michal Hocko
2016-09-19 12:03     ` Michal Hocko
2016-09-19 15:43   ` Vladimir Davydov
2016-09-19 15:43     ` Vladimir Davydov
2016-09-14 19:48 ` [PATCH 3/3] mm: memcontrol: consolidate cgroup socket tracking Johannes Weiner
2016-09-14 19:48   ` Johannes Weiner
2016-09-14 20:45   ` Tejun Heo
2016-09-14 20:45     ` Tejun Heo
2016-09-14 21:12   ` kbuild test robot
2016-09-14 21:12   ` kbuild test robot
2016-09-15  5:34   ` kbuild test robot
2016-09-14 22:17     ` Andrew Morton
2016-09-14 22:17       ` Andrew Morton
2016-09-15 14:27       ` Johannes Weiner
2016-09-15 14:27         ` Johannes Weiner
2016-09-19 12:04   ` Michal Hocko
2016-09-19 12:04     ` Michal Hocko
2016-09-19 12:01 ` [PATCH 1/3] mm: memcontrol: make per-cpu charge cache IRQ-safe for socket accounting Michal Hocko
2016-09-19 12:01   ` Michal Hocko
2016-09-19 15:35 ` Vladimir Davydov [this message]
2016-09-19 15:35   ` Vladimir Davydov

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