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Thu, 23 Mar 2023 08:56:14 -0700 (PDT) Date: Thu, 23 Mar 2023 11:56:13 -0400 From: Johannes Weiner To: Yosry Ahmed Cc: Tejun Heo , Josef Bacik , Jens Axboe , Zefan Li , Michal Hocko , Roman Gushchin , Shakeel Butt , Muchun Song , Andrew Morton , Vasily Averin , cgroups@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, bpf@vger.kernel.org Subject: Re: [RFC PATCH 4/7] memcg: sleep during flushing stats in safe contexts Message-ID: <20230323155613.GC739026@cmpxchg.org> References: <20230323040037.2389095-1-yosryahmed@google.com> <20230323040037.2389095-5-yosryahmed@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230323040037.2389095-5-yosryahmed@google.com> X-Rspamd-Queue-Id: AC505100011 X-Rspamd-Server: rspam09 X-Rspam-User: X-Stat-Signature: 14m9t67y76reo4g63is8reji6dpc5f91 X-HE-Tag: 1679586975-704513 X-HE-Meta: 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 DrXbgw8Z rVSjcDrZBKZGeZmIGDEQV/stGq9oRCgx+T8zD8kUT2fpU+BypMqaB1uKW/bK1fphA1ldinmfftoe78kGWCGsY+qVbRIUzerhbgiJX+3XJVd5IvvRA1jShqhEE/hknyCY0yoZlxWGY7O+XChP3Q1Ja01sJeaiplnR4kKx76oLqD9MLVjAxQQzdvR0zQ8BgOUwsOhPXlwXC0B6X9rYtGrHOrJqpvC3poHiBzKK7f1/arM4bPet6k5XKn7xJ2lgBXTFSTJ/eB30UznayM7SSeJKivOura3g0f5sb4gehib6BRkrNk8NtawiiLSR7Aiy0PD9s5+1KWngHaUpY0S2LI+uVMzQdtXyScnxMKIKf6UGgymsId56xzrAKUSGHWUQR+C9I7BHqeXb7OXj1nVj6E8N5rReB+mfdFswoWxiqkNc6QSC+G8B2Azh0EKWDsXko8nSA3/zE+lkreYpbiivnhrLhKDxhVzquBIS0PgXq61olllElgEc= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Mar 23, 2023 at 04:00:34AM +0000, Yosry Ahmed wrote: > @@ -644,26 +644,26 @@ static void __mem_cgroup_flush_stats(void) > return; > > flush_next_time = jiffies_64 + 2*FLUSH_TIME; > - cgroup_rstat_flush(root_mem_cgroup->css.cgroup, false); > + cgroup_rstat_flush(root_mem_cgroup->css.cgroup, may_sleep); How is it safe to call this with may_sleep=true when it's holding the stats_flush_lock? > atomic_set(&stats_flush_threshold, 0); > spin_unlock(&stats_flush_lock); > }