From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vladimir Davydov 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 Message-ID: <20160919153545.GF1989@esperanza> References: <20160914194846.11153-1-hannes@cmpxchg.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Andrew Morton , Tejun Heo , "David S. Miller" , Michal Hocko , linux-mm@kvack.org, cgroups@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@fb.com To: Johannes Weiner Return-path: Content-Disposition: inline In-Reply-To: <20160914194846.11153-1-hannes@cmpxchg.org> Sender: owner-linux-mm@kvack.org List-Id: netdev.vger.kernel.org On Wed, Sep 14, 2016 at 03:48:44PM -0400, Johannes Weiner wrote: > From: Johannes Weiner > > 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: # 4.5+ > Signed-off-by: Johannes Weiner Acked-by: Vladimir Davydov -- 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: email@kvack.org