From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail202.messagelabs.com (mail202.messagelabs.com [216.82.254.227]) by kanga.kvack.org (Postfix) with ESMTP id D2EF16B0011 for ; Wed, 27 Apr 2011 12:54:39 -0400 (EDT) Content-Type: text/plain; charset=UTF-8 From: Chris Mason Subject: Re: [BUG] fatal hang untarring 90GB file, possibly writeback related. In-reply-to: <1303923000.2583.8.camel@mulgrave.site> References: <1303920553.2583.7.camel@mulgrave.site> <1303921583-sup-4021@think> <1303923000.2583.8.camel@mulgrave.site> Date: Wed, 27 Apr 2011 12:54:26 -0400 Message-Id: <1303923177-sup-2603@think> Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org List-ID: To: James Bottomley Cc: linux-fsdevel , linux-mm , linux-kernel Excerpts from James Bottomley's message of 2011-04-27 12:50:00 -0400: > On Wed, 2011-04-27 at 12:33 -0400, Chris Mason wrote: > > Probably easier to debug with a sysrq-l and sysrq-w. > > Yes, just enabling them for the repro ... I didn't echo 1 > > /proc/sys/kernel/sysrq first time around > > > If you get stuck > > on the filesystem, it is probably waiting on ram, which it probably > > can't get because kswapd is spinning. Eventually everyone backs up > > waiting for the transaction that never ends. If we're really lucky it > > is just GFP_KERNEL where it should NOFS. > > > > Since you're often stuck in different spots inside shrink_slab, we're > > probably not stuck on a lock. But, trying with lock debugging, lockdep > > enabled and preempt on is a good idea to rule out locking mistakes. > > > > Does the fedora debug kernel enable preempt? > > No ... I've taken the Fedora 15 kernel config directly from their > install CD for this (with a bit of munging to get it to work on -rc4) Ok, I'd try turning it on so we catch the sleeping with a spinlock held case better. -chris -- 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 internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org