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[209.85.220.65]) by mx.google.com with SMTPS id y125sor7475297lfc.63.2019.04.30.02.08.09 for (Google Transport Security); Tue, 30 Apr 2019 02:08:09 -0700 (PDT) Received-SPF: pass (google.com: domain of gorcunov@gmail.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=KCIillAx; spf=pass (google.com: domain of gorcunov@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=gorcunov@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=9HjQ88MY4ZiDc1bI5n4MIBBh4bZ2A3E/q/QZEBk7alU=; b=KCIillAxrZrXB5w7B79fb19nYg7F3YCwf/ztmA9aoE9VUD7WLkEyGA1XTGj7Kk7I9I Q513ZwfxLRI6HJ4DrN1ZMjXfa842QSSs6yPwd0FUt+xZKwllptZpyag00LUFcGYK3EsC XdEbFchQbx1GNf/krTIlE74LPo3MefjF2xV0uZ5Rt9BcNTBf/J2/0tgE/CjrS+/46uwD ARjeDWBBqlnHHRKTKdiGH05RWZ9Qh2z5qOAaNQx9+9uWyCnSM+J6HGsn9mtkAkyisNb6 WLz5Pn17WNGE47oaQuTDdvGZvJ9oPYfrIEusa3M0SiUmfS8nh2ODl35nGOliRsB/77U5 zOrQ== X-Google-Smtp-Source: APXvYqxC1zZd7LprV/dgF44Ba5ne0SfC/5gxd6UPTeJBnWPoKvFHoqjjCKTMw2d90XkBC0hQgb2Gkw== X-Received: by 2002:a19:f50f:: with SMTP id j15mr36291099lfb.135.1556615289352; Tue, 30 Apr 2019 02:08:09 -0700 (PDT) Received: from uranus.localdomain ([5.18.103.226]) by smtp.gmail.com with ESMTPSA id u22sm1374696lji.40.2019.04.30.02.08.08 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 30 Apr 2019 02:08:08 -0700 (PDT) Received: by uranus.localdomain (Postfix, from userid 1000) id 45A444603CA; Tue, 30 Apr 2019 12:08:08 +0300 (MSK) Date: Tue, 30 Apr 2019 12:08:08 +0300 From: Cyrill Gorcunov To: Kirill Tkhai Cc: Michal =?iso-8859-1?Q?Koutn=FD?= , 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 Subject: Re: [PATCH 3/3] prctl_set_mm: downgrade mmap_sem to read lock Message-ID: <20190430090808.GC2673@uranus.lan> References: <20190418182321.GJ3040@uranus.lan> <20190430081844.22597-1-mkoutny@suse.com> <20190430081844.22597-4-mkoutny@suse.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.11.3 (2019-02-01) 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 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.