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[185.231.240.75]) by mx.google.com with ESMTPS id t9si6554569ljj.93.2019.04.30.02.11.42 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 30 Apr 2019 02:11:42 -0700 (PDT) Received-SPF: pass (google.com: domain of ktkhai@virtuozzo.com designates 185.231.240.75 as permitted sender) client-ip=185.231.240.75; Authentication-Results: mx.google.com; spf=pass (google.com: domain of ktkhai@virtuozzo.com designates 185.231.240.75 as permitted sender) smtp.mailfrom=ktkhai@virtuozzo.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=virtuozzo.com Received: from [172.16.25.169] by relay.sw.ru with esmtp (Exim 4.91) (envelope-from ) id 1hLOnZ-0007Uk-Vy; Tue, 30 Apr 2019 12:11:38 +0300 Subject: Re: [PATCH 3/3] prctl_set_mm: downgrade mmap_sem to read lock To: Cyrill Gorcunov Cc: =?UTF-8?Q?Michal_Koutn=c3=bd?= , akpm@linux-foundation.org, arunks@codeaurora.org, brgl@bgdev.pl, geert+renesas@glider.be, ldufour@linux.ibm.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, mguzik@redhat.com, mhocko@kernel.org, rppt@linux.ibm.com, vbabka@suse.cz References: <20190418182321.GJ3040@uranus.lan> <20190430081844.22597-1-mkoutny@suse.com> <20190430081844.22597-4-mkoutny@suse.com> <20190430090808.GC2673@uranus.lan> From: Kirill Tkhai Message-ID: <0a48e0a2-a282-159e-a56e-201fbc0faa91@virtuozzo.com> Date: Tue, 30 Apr 2019 12:11:37 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <20190430090808.GC2673@uranus.lan> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit 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 30.04.2019 12:08, Cyrill Gorcunov wrote: > On Tue, Apr 30, 2019 at 11:55:45AM +0300, Kirill Tkhai wrote: >>> - up_write(&mm->mmap_sem); >>> + spin_unlock(&mm->arg_lock); >>> + up_read(&mm->mmap_sem); >>> return error; >> >> Hm, shouldn't spin_lock()/spin_unlock() pair go as a fixup to existing code >> in a separate patch? >> >> Without them, the existing code has a problem at least in get_mm_cmdline(). > > Seems reasonable to merge it into patch 1. Sounds sensibly.