From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail191.messagelabs.com (mail191.messagelabs.com [216.82.242.19]) by kanga.kvack.org (Postfix) with ESMTP id 6879D6B0047 for ; Fri, 20 Mar 2009 11:59:44 -0400 (EDT) Received: from zps36.corp.google.com (zps36.corp.google.com [172.25.146.36]) by smtp-out.google.com with ESMTP id n2K70JU1009243 for ; Fri, 20 Mar 2009 07:00:19 GMT Received: from wf-out-1314.google.com (wfc25.prod.google.com [10.142.3.25]) by zps36.corp.google.com with ESMTP id n2K70H4m014917 for ; Fri, 20 Mar 2009 00:00:17 -0700 Received: by wf-out-1314.google.com with SMTP id 25so999399wfc.14 for ; Fri, 20 Mar 2009 00:00:17 -0700 (PDT) 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 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org To: Linus Torvalds Cc: Andrew Morton , linux-kernel , linux-mm , guichaz@gmail.com, Alex Khesin , Mike Waychison , Rohit Seth , Nick Piggin , Peter Zijlstra List-ID: 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 reproduce= d 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 t= hat >> > was fixed for a while. >> >> I tried 2.6.24 for couple of hours and the problem not happening yet. Wh= ile >> 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 confir= m > 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 > > =A0- 8bc3be2751b4f74ab90a446da1912fd8204d53f7: "writeback: speed up > =A0 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 trigger= ed the problem. > > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0Linus > -- 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