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[195.135.220.15]) by mx.google.com with ESMTPS id j5si517098ejb.211.2019.07.18.01.30.17 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 18 Jul 2019 01:30:17 -0700 (PDT) Received-SPF: pass (google.com: domain of mhocko@suse.com designates 195.135.220.15 as permitted sender) client-ip=195.135.220.15; Authentication-Results: mx.google.com; spf=pass (google.com: domain of mhocko@suse.com designates 195.135.220.15 as permitted sender) smtp.mailfrom=mhocko@suse.com X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 7B239ACB8; Thu, 18 Jul 2019 08:30:17 +0000 (UTC) Date: Thu, 18 Jul 2019 10:30:14 +0200 From: Michal Hocko To: Tetsuo Handa Cc: linux-mm@kvack.org, Roman Gushchin , Shakeel Butt , Andrew Morton Subject: Re: [PATCH] mm, oom: avoid printk() iteration under RCU Message-ID: <20190718083014.GB30461@dhcp22.suse.cz> References: <1563360901-8277-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1563360901-8277-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp> User-Agent: Mutt/1.10.1 (2018-07-13) 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 Wed 17-07-19 19:55:01, Tetsuo Handa wrote: > Currently dump_tasks() might call printk() for many thousands times under > RCU, which might take many minutes for slow consoles. Is is even wise to enable dumping tasks on systems with thousands of tasks and slow consoles? I mean you still have to call printk that is slow that many times. So why do we actually care? Because of RCU stall warnings? -- Michal Hocko SUSE Labs