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[195.92.253.2]) by mx.google.com with ESMTPS id o10si13130321wru.18.2019.04.04.14.58.44 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 04 Apr 2019 14:58:44 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of viro@ftp.linux.org.uk designates 195.92.253.2 as permitted sender) client-ip=195.92.253.2; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of viro@ftp.linux.org.uk designates 195.92.253.2 as permitted sender) smtp.mailfrom=viro@ftp.linux.org.uk Received: from viro by ZenIV.linux.org.uk with local (Exim 4.92 #3 (Red Hat Linux)) id 1hCAN8-0007xG-8f; Thu, 04 Apr 2019 21:58:10 +0000 Date: Thu, 4 Apr 2019 22:58:10 +0100 From: Al Viro To: "Tobin C. Harding" Cc: "Tobin C. Harding" , Andrew Morton , Roman Gushchin , Alexander Viro , Christoph Hellwig , Pekka Enberg , David Rientjes , Joonsoo Kim , Christopher Lameter , Matthew Wilcox , Miklos Szeredi , Andreas Dilger , Waiman Long , Tycho Andersen , Theodore Ts'o , Andi Kleen , David Chinner , Nick Piggin , Rik van Riel , Hugh Dickins , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Linus Torvalds Subject: Re: [RFC PATCH v2 14/14] dcache: Implement object migration Message-ID: <20190404215810.GG2217@ZenIV.linux.org.uk> References: <20190403042127.18755-1-tobin@kernel.org> <20190403042127.18755-15-tobin@kernel.org> <20190403170811.GR2217@ZenIV.linux.org.uk> <20190403171920.GS2217@ZenIV.linux.org.uk> <20190403174855.GT2217@ZenIV.linux.org.uk> <20190404202914.GA16709@eros.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190404202914.GA16709@eros.localdomain> 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, Apr 05, 2019 at 07:29:14AM +1100, Tobin C. Harding wrote: > > __d_alloc() is not holding ->d_lock, since the object is not visible to > > anybody else yet; with your changes it *is* visible. > > I don't quite understand this comment. How is the object visible? The > constructor is only called when allocating a new page to the slab and > this is done with interrupts disabled. Not to constructor, to your try-to-evict code...