From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with ESMTP id A03456B0089 for ; Mon, 6 Dec 2010 07:36:46 -0500 (EST) In-reply-to: <20101203085350.55f94057@xenia.leun.net> (message from Michael Leun on Fri, 3 Dec 2010 08:53:50 +0100) Subject: Re: kernel BUG at mm/truncate.c:475! References: <20101130194945.58962c44@xenia.leun.net> <20101201124528.6809c539@xenia.leun.net> <20101202084159.6bff7355@xenia.leun.net> <20101202091552.4a63f717@xenia.leun.net> <20101202115722.1c00afd5@xenia.leun.net> <20101203085350.55f94057@xenia.leun.net> Message-Id: From: Miklos Szeredi Date: Mon, 06 Dec 2010 13:36:30 +0100 Sender: owner-linux-mm@kvack.org To: Michael Leun Cc: miklos@szeredi.hu, hughd@google.com, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: On Fri, 3 Dec 2010, Michael Leun wrote: > On Thu, 2 Dec 2010 11:57:22 +0100 > Michael Leun wrote: > > > > Can you please describe in detail the workload that's causing this > > > to happen? > > > > Thats rather complicated, but I'll try. Basically it boils down to: > > > > unshare -n -m /bin/bash > > unionfs -o > > cow,suid,allow_other,max_files=65536 /home/netenv/user1-union=RW:/=RO /home/netenv/user1 > > mount -n -t proc none /home/netenv/user1/proc mount -n -t sysfs > > none /home/netenv/user1/sys mount -n -t devtmpfs > > devtmpfs /home/netenv/user1/dev mount -n -t devpts > > devpts /home/netenv/user1/dev/pts chroot /home/netenv/user1 /bin/su - > > user1 > [...] > > In some of this setups two or more environments share the same > > writable branch, so the files in this environments changed against > > real root of the machine are the same, e.g.: > > > > [...] > > unionfs -o > > cow,suid,allow_other,max_files=65536 /home/netenv/commondir=RW:/=RO /home/netenv/user1 > > [...] > > > > and another one > > > > [...] > > unionfs -o > > cow,suid,allow_other,max_files=65536 /home/netenv/commondir=RW:/=RO /home/netenv/user2 > > [...] > > Additional note: Happens also WITHOUT that "two unionfs mounts use the > same branch dir" stuff. Thanks. For you the workaround would be to use the "kernel_cache" option which disables cache invalidation on open. I'll try to reproduce the BUG on my machine, and if I don't succeed I'll need som more help from you. Also could you please send me your kernel .config > > Really seems to happen much more often in 2.6.36.1 than in 2.6.36. Probably just coincidence. Sometimes the frequency a bug shows up depends on code layout (and hence cache layout) differences, which can vary from compile to compile and even from one boot to the next. Thanks, Miklos -- 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/ . Fight unfair telecom policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: email@kvack.org