linux-kernel - Re: 2.6.22-rc4-mm2: GPF during suspend to RAM on HPC nx6325

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Message-Id: <200706130009.51278.rjw@sisk.pl>
Date:	Wed, 13 Jun 2007 00:09:50 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Tejun Heo <htejun@...il.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Greg KH <greg@...ah.com>, LKML <linux-kernel@...r.kernel.org>
Subject: Re: 2.6.22-rc4-mm2: GPF during suspend to RAM on HPC nx6325

On Tuesday, 12 June 2007 23:55, Rafael J. Wysocki wrote:
> On Monday, 11 June 2007 09:17, Tejun Heo wrote:
> > Hello, Rafael.
> > 
> > Rafael J. Wysocki wrote:
> > > gregkh-driver-sysfs-use-singly-linked-list-for-sysfs_dirent-tree.patch breaks
> > > suspend to RAM on HPC nx6325 (x86_64).
> > > 
> > > With this patch applied I get a general protection fault in mutex_lock+0x15
> > > (kernel/mutex.c:91), called by sysfs_hash_and_remove() (fs/sysfs/inode.c:298),
> > > called by threshold_cpu_callback(), called from _cpu_down().
> > 
> > I'm not sure whether this is bug in sysfs or in sysfs handling code in
> > mce_amd and I can't test mce_amd here.  Can you please apply the
> > attached patch and post the resulting dmesg including oops?
> 
> I've applied the patch, but the oops is a kernel panic, so I can't generate a
> dmesg including it. ;-)
> 
> Here's the dmesg output from a fresh boot (runlevel 2):
> 
> http://www.sisk.pl/kernel/debug/2.6.22-rc4-mm2/dmesg.log
> 
> Here's a picture of the oops taken after a failed attempt to suspend:
> 
> http://www.sisk.pl/kernel/debug/2.6.22-rc4-mm2/during_suspend.jpg
> 
> Here's a picture of the oops taken after a failed attempt to offline CPU1
> using 'echo 1 > /sys/devices/system/cpu/cpu1/online':
> 
> http://www.sisk.pl/kernel/debug/2.6.22-rc4-mm2/after_offlining_cpu1.jpg
> 
> [Sorry for the quality of pictures, I couldn't get anything better.]

More information:

With the debug patch applied the oops is a NULL pointer dereference
at sysfs_hash_and_remove+0x16, which according to gdb is

(gdb) l *sysfs_hash_and_remove+0x16
0xffffffff802d4bff is in sysfs_hash_and_remove (/home/rafael/src/mm/linux-2.6.22-rc4-mm2/fs/sysfs/inode.c:294).
289             int found = 0;
290
291             if (!dir)
292                     return -ENOENT;
293
294             if (dir->d_inode == NULL)
295                     /* no inode means this hasn't been made visible yet */
296                     return -ENOENT;
297
298             mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);

That doesn't make much sense to me, but it's 100% reproducible.

Greetings,
Rafael


-- 
"Premature optimization is the root of all evil." - Donald Knuth
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