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Tue, 10 Apr 2018 10:29:30 -0400 Received: from resqmta-po-12v.sys.comcast.net ([96.114.154.171]:51750 "EHLO resqmta-po-12v.sys.comcast.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753090AbeDJO3a (ORCPT ); Tue, 10 Apr 2018 10:29:30 -0400 Date: Tue, 10 Apr 2018 09:21:20 -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: <20180410125351.15837-1-willy@infradead.org> 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: MS4wfBkChvRlASOl+lo9K+AwiU6LxkT8MbEcaHqvHcSIW4dO/VptPDF7J9sHRIyTUWWHUETTjtDuFNkXwwvAMK1QDOqYpzVk14uB37kYHnMz2p3jPzJcqkWg PqSMokymvRECmGJdXFVP0nTFDpDQPugXonVf/3wYct1hC/1Olyq/0fFhLZJs6we8gC4S+l4JcJETSr1LhWgQsgu3XDJ/HOBdslJRU9kfYcvXQdHN9+7nf089 cWhIf9a2163BPdA1BX3/UBqgTEuoF8AbgCepkUs5UQQs0fnJV4EZKc9d1l3BZiYdn2abjeJQkSJagKZM1x5j63LZkdoQe684gUI7M0Z4/67z5lRD/OxD9E3J bgQ+LxOVmB/UwkGERNMsSFvfcWinUXaht+o3F8Syb5jPscbCw3lWlYaVwlNI0twXiwbyHBvkRJmwXOK5AJ+RpQGXp7DKpCMdkzqg6g6mHzLVQpQLSXO27eCD AYDTRmlWZyYwwj1guyKRmqqMGrd1EBdTIB1aid830uCVSnjgTsoK8zoOcvs= 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: > __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()?