From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Cyrus-Session-Id: sloti22d1t05-3875449-1523365671-2-16779047294769986432 X-Sieve: CMU Sieve 3.0 X-Spam-known-sender: no X-Spam-score: 0.0 X-Spam-hits: BAYES_00 -1.9, MAILING_LIST_MULTI -1, ME_NOAUTH 0.01, RCVD_IN_DNSWL_HI -5, LANGUAGES en, BAYES_USED global, SA_VERSION 3.4.0 X-Spam-source: IP='209.132.180.67', Host='vger.kernel.org', Country='US', FromHeader='org', MailFrom='org' X-Spam-charsets: plain='us-ascii' X-Resolved-to: greg@kroah.com X-Delivered-to: greg@kroah.com X-Mail-from: stable-owner@vger.kernel.org ARC-Seal: i=1; a=rsa-sha256; cv=none; d=messagingengine.com; s=fm2; t= 1523365670; b=i3FOJAve0rp2s8b45cMe2x3+K4VkiqLxIk04CtlK07ZsXgsyKF PyWc6pBOUSdfh43dnKg2k7f66Wm/TM/2VsZDFpOR72tLTwhB/xgNv1oVEtQwDlGN U8PN3nAwYJ3fbhIONpHicGtBdzaMuREINLfmcHDjwJz/R2UaFUnd10BLSW/XYIVn VT9aqTIFwlRsfbITl8PJv1dG/mvS/0+I7QFcPev0ujhsl5YpysEF8Y6AeF0zlujR XiTfhHG+NwCBsWF9Gx2LtvMWg1JPeNtIiDcOEm6pUDpvk0IsMJpuhSlXhOlv5MGa wNwLnq8COiuguGwNHlnCznk3JNN/f2pULMmw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=date:from:to:cc:subject:message-id :references:mime-version:content-type:in-reply-to:sender :list-id; s=fm2; t=1523365670; bh=vQyNRLSKY52aRp5d5gtAc50dF/i6Ky Dl1a6zi7R360I=; b=n6lvrtj9Bn8oucaKP761JeL9lJFXV080LHiUuydukFNTrH JkvHX1z9dWWSnQ3OZGS4q+r2y0DHPXIBiRU1nBXHUeRskwpHcuOxJU1C13yVf0Rn fz5cB1Vu5R5uI3cjeY4DEPoMw3Dgy3L+V5dBXhyZ3rMAY1iQW8k/vheh5/9m+O1P fMNeLIEz2xPpDRlN42DJO+3LnNDOZgpQ0Y2b7xvHaZOLEsICPL3WwBiYEkHGIq1v 3kZsZWc2WxazNghlSWqxatvTTOb1tY9+2OcdJOp6hcjmV7UschwfL7eCOmnqJirK QRm+zfB8yk5cHYLUiICROj3wG4wtCqIT7uvdwZbQ== ARC-Authentication-Results: i=1; mx2.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=kernel.org; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=orgdomain_pass (Domain org match); x-cm=none score=0; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=kernel.org header.result=pass header_is_org_domain=yes; x-vs=clean score=-100 state=0 Authentication-Results: mx2.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=kernel.org; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=orgdomain_pass (Domain org match); x-cm=none score=0; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=kernel.org header.result=pass header_is_org_domain=yes; x-vs=clean score=-100 state=0 X-ME-VSCategory: clean X-CM-Envelope: MS4wfGduAkkYnZWRIQRusuF/fO1t9XzikcKQo2h6i0cJD0NzIlTbdtko2AhLD7W56x1IV5R/AoAsfy41xINw7IULta/Y0P4dzjJtW+5HhgjQAc3r70ZbAaXq Awd7rmX5N5X41XzyDYMvwYFD0mYJyoQvOG73R+8gcDjuqU0gvDDurlVEbtQyTQQ5exP37HPxXs1cHKJSi9Cnqenjrx3/usTc5zeU3kGzxUarcJu7ByS5ovQj X-CM-Analysis: v=2.3 cv=E8HjW5Vl c=1 sm=1 tr=0 a=UK1r566ZdBxH71SXbqIOeA==:117 a=UK1r566ZdBxH71SXbqIOeA==:17 a=kj9zAlcOel0A:10 a=Kd1tUaAdevIA:10 a=yMhMjlubAAAA:8 a=VwQbUJbxAAAA:8 a=wFfjXEGv2hVsUhVf7DgA:9 a=CjuIK1q_8ugA:10 a=AjGcO6oz07-iQ99wixmX:22 X-ME-CMScore: 0 X-ME-CMCategory: none Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752807AbeDJNHr (ORCPT ); Tue, 10 Apr 2018 09:07:47 -0400 Received: from mx2.suse.de ([195.135.220.15]:46983 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752752AbeDJNHr (ORCPT ); Tue, 10 Apr 2018 09:07:47 -0400 Date: Tue, 10 Apr 2018 15:07:42 +0200 From: Michal Hocko To: Matthew Wilcox Cc: linux-mm@kvack.org, Matthew Wilcox , Christoph Lameter , 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 Message-ID: <20180410130742.GM21835@dhcp22.suse.cz> References: <20180410125351.15837-1-willy@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180410125351.15837-1-willy@infradead.org> User-Agent: Mutt/1.9.4 (2018-02-28) 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 10-04-18 05:53:50, Matthew Wilcox wrote: > From: Matthew Wilcox > > __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. > > Fixes: d07dbea46405 ("Slab allocators: support __GFP_ZERO in all allocators") > Signed-off-by: Matthew Wilcox > Cc: stable@vger.kernel.org > --- > mm/slab.c | 6 ++++-- > mm/slob.c | 4 +++- > mm/slub.c | 6 ++++-- > 3 files changed, 11 insertions(+), 5 deletions(-) > > diff --git a/mm/slab.c b/mm/slab.c > index 38d3f4fd17d7..8b2cb7db85db 100644 > --- a/mm/slab.c > +++ b/mm/slab.c > @@ -3313,8 +3313,10 @@ slab_alloc_node(struct kmem_cache *cachep, gfp_t flags, int nodeid, > local_irq_restore(save_flags); > ptr = cache_alloc_debugcheck_after(cachep, flags, ptr, caller); > > - if (unlikely(flags & __GFP_ZERO) && ptr) > - memset(ptr, 0, cachep->object_size); > + if (unlikely(flags & __GFP_ZERO) && ptr) { > + if (!WARN_ON_ONCE(cachep->ctor)) > + memset(ptr, 0, cachep->object_size); > + } > > slab_post_alloc_hook(cachep, flags, 1, &ptr); > return ptr; Why don't we need to cover this in slab_alloc and kmem_cache_alloc_bulk as well? Other than that this patch makes sense to me. -- Michal Hocko SUSE Labs