From: Jon Nelson Subject: Re: hunt for 2.6.37 dm-crypt+ext4 corruption? (was: Re: dm-crypt barrier support is effective) Date: Tue, 7 Dec 2010 21:29:26 -0600 Message-ID: References: <4CF692D1.1010906@redhat.com> <4CF6B3E8.2000406@redhat.com> <20101201212310.GA15648@redhat.com> <20101204193828.GB13871@redhat.com> <20101207142145.GA27861@think> <20101207182243.GB21112@redhat.com> <1291747731-sup-3099@think> <1291751698-sup-9297@think> <1291754340-sup-1631@think> <1291755258-sup-8760@think> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Mike Snitzer , Matt , Milan Broz , Andi Kleen , linux-btrfs , dm-devel , Linux Kernel , htd , htejun , linux-ext4 To: Chris Mason Return-path: Received: from mail-bw0-f66.google.com ([209.85.214.66]:45952 "EHLO mail-bw0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753819Ab0LHD3t convert rfc822-to-8bit (ORCPT ); Tue, 7 Dec 2010 22:29:49 -0500 In-Reply-To: <1291755258-sup-8760@think> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Tue, Dec 7, 2010 at 3:02 PM, Chris Mason wr= ote: > Excerpts from Jon Nelson's message of 2010-12-07 15:48:58 -0500: >> On Tue, Dec 7, 2010 at 2:41 PM, Chris Mason = wrote: >> > Excerpts from Jon Nelson's message of 2010-12-07 15:25:47 -0500: >> >> On Tue, Dec 7, 2010 at 2:02 PM, Chris Mason wrote: >> >> > Excerpts from Jon Nelson's message of 2010-12-07 14:34:40 -0500= : >> >> >> On Tue, Dec 7, 2010 at 12:52 PM, Chris Mason wrote: >> >> >> >> postgresql errors. Typically, header corruption but from th= e limited >> >> >> >> visibility I've had into this via strace, what I see is zer= oed pages >> >> >> >> where there shouldn't be. >> >> >> > >> >> >> > This sounds a lot like a bug higher up than dm-crypt. =C2=A0= Zeros tend to >> >> >> > come from some piece of code explicitly filling a page with = zeros, and >> >> >> > that often happens in the corner cases for O_DIRECT and a fe= w other >> >> >> > places in the filesystem. >> >> >> > >> >> >> > Have you tried triggering this with a regular block device? >> >> >> >> >> >> I just tried the whole set of tests, but with /dev/sdb directl= y (as >> >> >> ext4) without any crypt-y bits. >> >> >> It takes more iterations but out of 6 tests I had one failure:= same >> >> >> type of thing, 'invalid page header in block ....'. >> >> >> >> >> >> I can't guarantee that it is a full-page of zeroes, just what = I saw >> >> >> from the (limited) stracing I did. >> >> > >> >> > Fantastic. Now for our usual suspects: Maybe not so fantastic. I kept testing and had no more failures. At all. After 40+ iterations I gave up. I went back to trying ext4 on a LUKS volume. The 'hit' ratio went to something like 1 in 3, or better. I will continue to do testing with and without LUKS. I did /not/ reboot between tests, but I do start with a fresh postgres database. --=20 Jon -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html