From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752067AbdJFMLv convert rfc822-to-8bit (ORCPT ); Fri, 6 Oct 2017 08:11:51 -0400 Received: from smtp-out4.electric.net ([192.162.216.181]:53838 "EHLO smtp-out4.electric.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751901AbdJFMLt (ORCPT ); Fri, 6 Oct 2017 08:11:49 -0400 From: David Laight To: "'Michal Hocko'" CC: "'Pavel Tatashin'" , "linux-kernel@vger.kernel.org" , "sparclinux@vger.kernel.org" , "linux-mm@kvack.org" , "linuxppc-dev@lists.ozlabs.org" , "linux-s390@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "x86@kernel.org" , "kasan-dev@googlegroups.com" , "borntraeger@de.ibm.com" , "heiko.carstens@de.ibm.com" , "davem@davemloft.net" , "willy@infradead.org" , "ard.biesheuvel@linaro.org" , "mark.rutland@arm.com" , "will.deacon@arm.com" , "catalin.marinas@arm.com" , "sam@ravnborg.org" , "mgorman@techsingularity.net" , "steven.sistare@oracle.com" , "daniel.m.jordan@oracle.com" , "bob.picco@oracle.com" Subject: RE: [PATCH v10 09/10] mm: stop zeroing memory during allocation in vmemmap Thread-Topic: [PATCH v10 09/10] mm: stop zeroing memory during allocation in vmemmap Thread-Index: AQHTPiBCEou4JKZYKEiOcV6UcmF+z6LWqmnQ///6WYCAABcNQA== Date: Fri, 6 Oct 2017 12:11:42 +0000 Message-ID: <063D6719AE5E284EB5DD2968C1650D6DD008BB4D@AcuExch.aculab.com> References: <20171005211124.26524-1-pasha.tatashin@oracle.com> <20171005211124.26524-10-pasha.tatashin@oracle.com> <063D6719AE5E284EB5DD2968C1650D6DD008BA85@AcuExch.aculab.com> <20171006114729.fexwklupkhyxdpt3@dhcp22.suse.cz> In-Reply-To: <20171006114729.fexwklupkhyxdpt3@dhcp22.suse.cz> Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.202.99.200] Content-Type: text/plain; charset="Windows-1252" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 X-Outbound-IP: 156.67.243.126 X-Env-From: David.Laight@ACULAB.COM X-Proto: esmtps X-Revdns: X-HELO: AcuExch.aculab.com X-TLS: TLSv1:AES128-SHA:128 X-Authenticated_ID: X-PolicySMART: 3396946, 3397078 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Michal Hocko > Sent: 06 October 2017 12:47 > On Fri 06-10-17 11:10:14, David Laight wrote: > > From: Pavel Tatashin > > > Sent: 05 October 2017 22:11 > > > vmemmap_alloc_block() will no longer zero the block, so zero memory > > > at its call sites for everything except struct pages. Struct page memory > > > is zero'd by struct page initialization. > > > > It seems dangerous to change an allocator to stop zeroing memory. > > It is probably saver to add a new function that doesn't zero > > the memory and use that is the places where you don't want it > > to be zeroed. > > Not sure what you mean. memblock_virt_alloc_try_nid_raw is a new > function which doesn't zero out... You should probably leave vmemap_alloc_block() zeroing the memory so that existing alls don't have to be changed - apart from the ones you are explicitly optimising. David