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[195.135.220.15]) by mx.google.com with ESMTPS id b28si2441065edn.15.2019.05.27.00.04.18 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 27 May 2019 00:04:18 -0700 (PDT) Received-SPF: softfail (google.com: domain of transitioning mhocko@kernel.org does not designate 195.135.220.15 as permitted sender) client-ip=195.135.220.15; Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning mhocko@kernel.org does not designate 195.135.220.15 as permitted sender) smtp.mailfrom=mhocko@kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=kernel.org 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 9EFD7AD9C; Mon, 27 May 2019 07:04:17 +0000 (UTC) Date: Mon, 27 May 2019 09:04:15 +0200 From: Michal Hocko To: Daniel Jordan Cc: "Potyra, Stefan" , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "Jordan, Tobias" , akpm@linux-foundation.org, vbabka@suse.cz, kirill.shutemov@linux.intel.com, linux-api@vger.kernel.org Subject: Re: [PATCH] mm: mlockall error for flag MCL_ONFAULT Message-ID: <20190527070415.GA1658@dhcp22.suse.cz> References: <20190522112329.GA25483@er01809n.ebgroup.elektrobit.com> <20190524214304.enntpu4tvzpyxzfe@ca-dmjordan1.us.oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20190524214304.enntpu4tvzpyxzfe@ca-dmjordan1.us.oracle.com> 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 Fri 24-05-19 17:43:04, Daniel Jordan wrote: > [ Adding linux-api and some of the people who were involved in the > MCL_ONFAULT/mlock2/etc discussions. Author of the Fixes patch appears to > have moved on. ] > > On Wed, May 22, 2019 at 11:23:37AM +0000, Potyra, Stefan wrote: > > If mlockall() is called with only MCL_ONFAULT as flag, > > it removes any previously applied lockings and does > > nothing else. > > The change looks reasonable. Hard to imagine any application relies on it, and > they really shouldn't be if they are. Debian codesearch turned up only a few > cases where stress-ng was doing this for unknown reasons[1] and this change > isn't gonna break those. In this case I think changing the syscall's behavior > is justified. > > > This behavior is counter-intuitive and doesn't match the > > Linux man page. > > I'd quote it for the changelog: > > For mlockall(): > > EINVAL Unknown flags were specified or MCL_ONFAULT was specified with‐ > out either MCL_FUTURE or MCL_CURRENT. > > With that you can add > > Reviewed-by: Daniel Jordan > > [1] https://sources.debian.org/src/stress-ng/0.09.50-1/stress-mlock.c/?hl=203#L203 Well spotted and the fix looks reasonable as well. Quoting the man page seems useful as well. Acked-by: Michal Hocko Thanks! -- Michal Hocko SUSE Labs