From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pd0-f181.google.com (mail-pd0-f181.google.com [209.85.192.181]) by kanga.kvack.org (Postfix) with ESMTP id 4B74E6B003C for ; Tue, 4 Feb 2014 19:06:44 -0500 (EST) Received: by mail-pd0-f181.google.com with SMTP id y10so8824569pdj.26 for ; Tue, 04 Feb 2014 16:06:43 -0800 (PST) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org. [140.211.169.12]) by mx.google.com with ESMTP id ay1si19408052pbd.216.2014.02.04.16.06.43 for ; Tue, 04 Feb 2014 16:06:43 -0800 (PST) Date: Tue, 4 Feb 2014 16:06:41 -0800 From: Andrew Morton Subject: Re: [patch] mm, page_alloc: make first_page visible before PageTail Message-Id: <20140204160641.8f5d369eeb2d0318618d6d5f@linux-foundation.org> In-Reply-To: References: <20140203122052.GC2495@dhcp22.suse.cz> <20140203162036.GJ2495@dhcp22.suse.cz> <52EFC93D.3030106@suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: David Rientjes Cc: Holger Kiehl , Christoph Lameter , Rafael Aquini , Vlastimil Babka , Michal Hocko , Mel Gorman , linux-kernel@vger.kernel.org, linux-mm@kvack.org On Tue, 4 Feb 2014 16:02:39 -0800 (PST) David Rientjes wrote: > Commit bf6bddf1924e ("mm: introduce compaction and migration for ballooned > pages") introduces page_count(page) into memory compaction which > dereferences page->first_page if PageTail(page). > > Introduce a store memory barrier to ensure page->first_page is properly > initialized so that code that does page_count(page) on pages off the lru > always have a valid p->first_page. Could we have a code comment please? Even checkpatch knows this rule! > Reported-by: Holger Kiehl What did Holger report? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org