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Tue, 10 Apr 2018 13:30:27 -0400 Received: from resqmta-ch2-10v.sys.comcast.net ([69.252.207.42]:42828 "EHLO resqmta-ch2-10v.sys.comcast.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752016AbeDJRa1 (ORCPT ); Tue, 10 Apr 2018 13:30:27 -0400 Date: Tue, 10 Apr 2018 12:30:23 -0500 (CDT) From: Christopher Lameter X-X-Sender: cl@nuc-kabylake To: Matthew Wilcox cc: Eric Dumazet , linux-mm@kvack.org, Matthew Wilcox , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , linux-kernel@vger.kernel.org, Jan Kara , Jeff Layton , Mel Gorman , stable@vger.kernel.org Subject: Re: [PATCH 1/2] slab: __GFP_ZERO is incompatible with a constructor In-Reply-To: <20180410165054.GC3614@bombadil.infradead.org> Message-ID: References: <20180410125351.15837-1-willy@infradead.org> <20180410165054.GC3614@bombadil.infradead.org> User-Agent: Alpine 2.20 (DEB 67 2015-01-07) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-CMAE-Envelope: MS4wfMT783t3W6VDnS5BMNi/dXae33+W6vKnGhR+4E6OtmIeuLQBz2eQrDhJeFxz/Ds14d+R12UAtRvAiJla837yr1wnifThlbeTskDdinZVC8A/sSbs20UX ma265iMQQKAk8GhZtA0pUJyLUFVXBpXbLxDxOWwPEausom3SgMVid4CEpVapGe3Dxisl9kpWUCL81A/OVSVq1AUu4qNP/02nW6WkyW/eec+FQiLra5gQhVwv 4WbJOeFshglwcm/UO5rbqceXg2dI47GT23n3nQppR+IqYx0hG0PhaGWfMlG3/bCWHgEiQW3h7kIDo7RFviWkV46OZhm6qnYg06Xv4+Mg7lr/KSZPVHzOsH55 Rr37SXYx2ZLA5Vv+MZHG3nJXl2Bkz4YC9QNKHwqwk8ye4CqHxaGumJzHW8OA2A7UbEwyKCVZlUtqilWNWXcWU1l2xMYNQLKt6PqpJSCPLPEfdDwOzQH9BHYf F86iK7RUPBk3sXWorZ4ZQZn20+qNdkWpnQAz7FAcou3WYKSTcZh/W+1/N1OrfgmnkTZxT8xYgyRaI9vaBo05Gz6OQwU+xetpsUsiCw== Sender: stable-owner@vger.kernel.org X-Mailing-List: stable@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On Tue, 10 Apr 2018, Matthew Wilcox wrote: > If we want to get rid of the concept of constructors, it's doable, > but somebody needs to do the work to show what the effects will be. How do you envision dealing with the SLAB_TYPESAFE_BY_RCU slab caches? Those must have a defined state of the objects at all times and a constructor is required for that. And their use of RCU is required for numerous lockless lookup algorithms in the kernhel.