Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753114Ab0LLMoK (ORCPT ); Sun, 12 Dec 2010 07:44:10 -0500 Received: from thunk.org ([69.25.196.29]:49508 "EHLO thunker.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752834Ab0LLMoH (ORCPT ); Sun, 12 Dec 2010 07:44:07 -0500 Date: Sun, 12 Dec 2010 07:43:54 -0500 From: "Ted Ts'o" To: Jon Nelson Cc: Matt , Chris Mason , Andi Kleen , Mike Snitzer , Milan Broz , linux-btrfs , dm-devel , Linux Kernel , htd , htejun , linux-ext4 Subject: Re: hunt for 2.6.37 dm-crypt+ext4 corruption? (was: Re: dm-crypt barrier support is effective) Message-ID: <20101212124354.GA4513@thunk.org> Mail-Followup-To: Ted Ts'o , Jon Nelson , Matt , Chris Mason , Andi Kleen , Mike Snitzer , Milan Broz , linux-btrfs , dm-devel , Linux Kernel , htd , htejun , linux-ext4 References: <1291945065-sup-1838@think> <20101210023852.GB3059@thunk.org> <20101212023415.GG3059@thunk.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.20 (2009-06-14) X-SA-Exim-Connect-IP: X-SA-Exim-Mail-From: tytso@thunk.org X-SA-Exim-Scanned: No (on thunker.thunk.org); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1356 Lines: 28 On Sun, Dec 12, 2010 at 04:18:29AM -0600, Jon Nelson wrote: > > I have one CPU configured in the environment, 512MB of memory. > > I have not done any memory-constriction tests whatsoever. I've finally been able to reproduce it myself, on real hardware. SMP is not necessary to reproduce it, although having more than one CPU doesn't hurt. What I did need to do (on real hardware with 4 gigs of memory) was to turn off swap and pin enough memory so that free memory was around 200megs or so before the start of the test. (This is the natural amount of free memory that the system would try to reach, since 200 megs is about 5% of 4 gigs.) Then, during the test, free memory would drop to 50-70 megabytes, forcing writeback to run, and then I could trigger it about 1-2 times out of three. I'm guessing that when you used 512mb of memory, that was in effect a memory-constriction test, and if you were to push the memory down a little further, it might reproduce even more quickly. My next step is to try to reproduce this in a VM, and then I can start probing to see what might be going on. - Ted -- 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/