From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 17 Jun 2008 19:33:32 +0100 (BST) From: Hugh Dickins Subject: Re: [PATCH][RFC] fix kernel BUG at mm/migrate.c:719! in 2.6.26-rc5-mm3 In-Reply-To: <1213724798.8707.41.camel@lts-notebook> Message-ID: References: <20080611225945.4da7bb7f.akpm@linux-foundation.org> <20080617163501.7cf411ee.nishimura@mxp.nes.nec.co.jp> <1213724798.8707.41.camel@lts-notebook> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Lee Schermerhorn Cc: Daisuke Nishimura , Andrew Morton , Rik van Riel , Kosaki Motohiro , Nick Piggin , linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-testers@vger.kernel.org List-ID: On Tue, 17 Jun 2008, Lee Schermerhorn wrote: > > Now I wonder if the assertion that newpage count == 1 could be violated? > I don't see how. We've just allocated and filled it and haven't > unlocked it yet, so we should hold the only reference. Do you agree? Disagree: IIRC, excellent example of the kind of assumption that becomes invalid with Nick's speculative page references. Someone interested in the previous use of the page may have incremented the refcount, and in due course will find that it's got reused for something else, and will then back off. Hugh -- 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