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Tue, 10 Apr 2018 10:34:29 -0400 Received: from resqmta-ch2-12v.sys.comcast.net ([69.252.207.44]:33528 "EHLO resqmta-ch2-12v.sys.comcast.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753258AbeDJOe3 (ORCPT ); Tue, 10 Apr 2018 10:34:29 -0400 Date: Tue, 10 Apr 2018 09:26:19 -0500 (CDT) From: Christopher Lameter X-X-Sender: cl@nuc-kabylake To: Matthew Wilcox cc: 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: Message-ID: References: <20180410125351.15837-1-willy@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: MS4wfEoSLJu4PEigK+VC8JBxRPvaQKIrS4szM3RGwOKicFCKKWnBZwmdSF65G4d6YKrdlBZ6k23iycY4eJSkftjo3FZRiXDaGO8C6JXcnbHQFcJt9j0ABPaI 7J2LF3TMYAzBAexY+NJtTJORESpH4KChhfGZuyqioEVpFE9eqZQX40njvAkviMkskFG/r2a3UYIGvWgJJXuI9fFZru/GLtRzR354FZY45VpKTwtUPLWlVcaA PzCLzG0qDLdasbC1Pec/Xbar/7lCKqYVbK6CwPBIwVFj9RRWkjoTNIlXNPZrle9PW1JR8i4Q2u+VtDEFpyqx5geBOBbgzHgjnDw717Qo1COHryFUkxzG5SpB EQnmNhyWw2aZyPb14UoGt6sfOEtOGpFAZ563yRFFI2L8S6PXh9aiB0VubacSwY6amMQHBE5ofAo6vJnO+yzMGissa8/vy6SDDx7HMJqGzMFuwixtdRGLTmuM mt9BgtCCdD4fkvgdeowyJ2+ibsYHNOii8ROfX78SBKpEAgr/9V0LBpPtYGo= 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, Christopher Lameter wrote: > On Tue, 10 Apr 2018, Matthew Wilcox wrote: > > > __GFP_ZERO requests that the object be initialised to all-zeroes, > > while the purpose of a constructor is to initialise an object to a > > particular pattern. We cannot do both. Add a warning to catch any > > users who mistakenly pass a __GFP_ZERO flag when allocating a slab with > > a constructor. > > Can we move this check out of the critical paths and check for > a ctor and GFP_ZERO when calling the page allocator? F.e. in > allocate_slab()? The ctor's are run at that point from setup_object() so it makes sense.