From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f169.google.com (mail-wi0-f169.google.com [209.85.212.169]) by kanga.kvack.org (Postfix) with ESMTP id 449356B0032 for ; Tue, 9 Dec 2014 04:59:27 -0500 (EST) Received: by mail-wi0-f169.google.com with SMTP id r20so9566891wiv.0 for ; Tue, 09 Dec 2014 01:59:26 -0800 (PST) Received: from mx2.suse.de (cantor2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id lj5si1224101wjc.60.2014.12.09.01.59.26 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Tue, 09 Dec 2014 01:59:26 -0800 (PST) Date: Tue, 9 Dec 2014 09:59:22 +0000 From: Mel Gorman Subject: Re: [PATCH] mm: page_alloc: place zone id check before VM_BUG_ON_PAGE check Message-ID: <20141209095922.GB21903@suse.de> References: <000001d01383$8e0f1120$aa2d3360$%yang@samsung.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <000001d01383$8e0f1120$aa2d3360$%yang@samsung.com> Sender: owner-linux-mm@kvack.org List-ID: To: Weijie Yang Cc: 'Andrew Morton' , 'Johannes Weiner' , 'Rik van Riel' , linux-mm@kvack.org, linux-kernel@vger.kernel.org, 'Weijie Yang' On Tue, Dec 09, 2014 at 03:40:35PM +0800, Weijie Yang wrote: > If the free page and its buddy has different zone id, the current > zone->lock cann't prevent buddy page getting allocated, this could > trigger VM_BUG_ON_PAGE in a very tiny chance: > Under what circumstances can a buddy page be allocated without the zone->lock? Any parallel allocation from that zone that takes place will be from the per-cpu allocator and should not be affected by this. Have you actually hit this race? -- Mel Gorman SUSE Labs -- 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