xfs
[Top] [All Lists]

Re: [PATCH] xfs: fix race while discarding buffers [V4]

To: Dave Chinner <david@xxxxxxxxxxxxx>, Carlos Maiolino <cmaiolino@xxxxxxxxxx>
Subject: Re: [PATCH] xfs: fix race while discarding buffers [V4]
From: Ben Myers <bpm@xxxxxxx>
Date: Fri, 24 Aug 2012 13:44:41 -0500
Cc: xfs@xxxxxxxxxxx
In-reply-to: <20120820232110.GM19235@dastard>
References: <1344621711-8049-1-git-send-email-cmaiolino@xxxxxxxxxx> <20120820205134.GB29979@xxxxxxx> <20120820224751.GA22096@xxxxxxxxxxxxxxxxxxxxxxxx> <20120820232110.GM19235@dastard>
User-agent: Mutt/1.5.20 (2009-06-14)
Carlos and Dave,

On Tue, Aug 21, 2012 at 09:21:10AM +1000, Dave Chinner wrote:
> On Mon, Aug 20, 2012 at 07:47:51PM -0300, Carlos Maiolino wrote:
> > Thanks for the comments.
> > > 
> > > What was the symptom that led to the discovery of this problem?
> > > 
> > > Reviewed-by: Ben Myers <bpm@xxxxxxx>
> > > 
> > 
> > It started with the messages like the example below being logged by syslog:
> > 
> > shrink_slab: xfs_buftarg_shrink+0x0/0x160 [xfs] negative objects to delete 
> > nr=-61993820
> > shrink_slab: xfs_buftarg_shrink+0x0/0x160 [xfs] negative objects to delete 
> > nr=-146
> > shrink_slab: xfs_buftarg_shrink+0x0/0x160 [xfs] negative objects to delete 
> > nr=-240601220
> > shrink_slab: xfs_buftarg_shrink+0x0/0x160 [xfs] negative objects to delete 
> > nr=-152
> > shrink_slab: xfs_buftarg_shrink+0x0/0x160 [xfs] negative objects to delete 
> > nr=-2921236993
> > 
> > These messages came from shrink_slab().
> 
> Worth noting is that this warning came from a RHEL kernel, not a
> mainline kernel. The mainline kernels don't screw up the nr_to_scan
> calculations when a negative object count is returned to them.
> Hence mainline kernels are not impacted by the accounting bug at
> all...

Thanks for the additional information.  Sometimes it is helpful to know the
symptom along with the fix.

Regards,
Ben

<Prev in Thread] Current Thread [Next in Thread>