Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755700AbaLIJ73 (ORCPT ); Tue, 9 Dec 2014 04:59:29 -0500 Received: from cantor2.suse.de ([195.135.220.15]:44970 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754396AbaLIJ71 (ORCPT ); Tue, 9 Dec 2014 04:59:27 -0500 Date: Tue, 9 Dec 2014 09:59:22 +0000 From: Mel Gorman To: Weijie Yang Cc: "'Andrew Morton'" , "'Johannes Weiner'" , "'Rik van Riel'" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, "'Weijie Yang'" 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> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/