Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753397AbZCTHAe (ORCPT ); Fri, 20 Mar 2009 03:00:34 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752692AbZCTHAZ (ORCPT ); Fri, 20 Mar 2009 03:00:25 -0400 Received: from smtp-out.google.com ([216.239.33.17]:15951 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752642AbZCTHAY convert rfc822-to-8bit (ORCPT ); Fri, 20 Mar 2009 03:00:24 -0400 DomainKey-Signature: a=rsa-sha1; s=beta; d=google.com; c=nofws; q=dns; h=mime-version:in-reply-to:references:date:message-id:subject:from:to: cc:content-type:content-transfer-encoding:x-system-of-record; b=nU1WfcUs6i+J7GntneKk8EKXYh6PM254NZ40PUQt5ApgNrq7tHHu8lvPsE88WTEnG j4acfQLXSezKtJ9U++MDw== MIME-Version: 1.0 In-Reply-To: References: <604427e00903181244w360c5519k9179d5c3e5cd6ab3@mail.gmail.com> <20090318151157.85109100.akpm@linux-foundation.org> <604427e00903191734l42376eebsee018e8243b4d6f5@mail.gmail.com> Date: Fri, 20 Mar 2009 00:00:17 -0700 Message-ID: <604427e00903200000n157a59a0od47b12975232d4cf@mail.gmail.com> Subject: Re: ftruncate-mmap: pages are lost after writing to mmaped file. From: Ying Han To: Linus Torvalds Cc: Andrew Morton , linux-kernel , linux-mm , guichaz@gmail.com, Alex Khesin , Mike Waychison , Rohit Seth , Nick Piggin , Peter Zijlstra Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT X-System-Of-Record: true Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2114 Lines: 50 On Thu, Mar 19, 2009 at 5:49 PM, Linus Torvalds wrote: > > > On Thu, 19 Mar 2009, Ying Han wrote: >> > >> > Ying Han - since you're all set up for testing this and have reproduced it >> > on multiple kernels, can you try it on a few more kernel versions? It >> > would be interesting to both go further back in time (say 2.6.15-ish), >> > _and_ check something like 2.6.21 which had the exact dirty accounting >> > fix. Maybe it's not really an old bug - maybe we re-introduced a bug that >> > was fixed for a while. >> >> I tried 2.6.24 for couple of hours and the problem not happening yet. While >> the same test on 2.6.25, the problem happen right away. > > Ok, so 2.6.25 is known bad. Can you test 2.6.24 a lot more, because we > should not decide that it's bug-free without a _lot_ of testing. > > But if it's a bug that has gone away and then re-appeared, it at least > explains how 2.6.21 (which got a fair amount of mmap testing) didn't have > lots of reports of mmap corruption. > > That said, I can think of nothing obvious in between 2.6.24 and .25 that > would have re-introduced it. But if some heavy testing really does confirm > that 2.6.24 doesn't have the problem, that is a good first step to trying > to narrow down where things started going wrong. > > That said, it could _easily_ be some timing-related pattern. One of the > things in between 2.6.24 and .25 is > > ?- 8bc3be2751b4f74ab90a446da1912fd8204d53f7: "writeback: speed up > ? writeback of big dirty files" > > which is that exact kind of "change the timing patterns, but don't change > anything fundamental" thing. > > Which is why I'd like you to continue testing 2.6.24 just to be _really_ > sure that it really doesn't happen there. Unfortunately, 2.6.24 is not immune. After running several hours, i triggered the problem. > > ? ? ? ? ? ? ? ?Linus > -- 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/