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SubjectRe: 2.6.19-rc3-git7: BUG: mutex warning sysfs_dir_open


On Tue, 31 Oct 2006, Mark Lord wrote:
>
> I found this in my syslog just now:
>
> kernel: BUG: warning at kernel/mutex.c:132/__mutex_lock_common()

That's the "spin_lock_mutex()" debugging (kernel/mutex-debug.h), and it's
one of either

DEBUG_LOCKS_WARN_ON(in_interrupt());
or
DEBUG_LOCKS_WARN_ON(l->magic != l);

where the much more likely one is the "l->magic" one triggering, because
your bug that follows is:

> kernel: BUG: unable to handle kernel paging request at virtual address 6e726574

64726574 is "tern", for whatever that's worth, and that EIP is in
"__list_add()", which comes from list_add_tail(), and so it looks like the
mutex "lock->lock_list" is also totally buggered (which would certainly
fit with the lock "magic" field being crud too).

> kernel: Call Trace:
> kernel: [<c035d76e>] __mutex_lock_slowpath+0x8e/0x260
> kernel: [<c035d961>] mutex_lock+0x21/0x30
> kernel: [<c01a0286>] sysfs_dir_open+0x26/0x60

This would be

mutex_lock(&dentry->d_inode->i_mutex);

in sysfs_dir_open(), so you would seem to have an inode that is
overwritten by crud (or it could be a dentry with a bogus d_inode
pointer, of course).

There's a ton of stuff with "tern" in it, mostly "Internal", so sadly even
the nice string pattern doesn't seem to be all that helpful.

Is this somewhat reproducible?

HOWEVER, google does find a clue. We've had reports of something somewhat
similar before: googling for "__mutex_lock_slowpath" and "sysfs_dir_open"
shows for example

http://lkml.org/lkml/2006/8/18/72

where the thread ended up first blaming sound, but then deciding that
maybe it was DRM-related. However, you don't seem to have any AGP or DRM
support at all, so maybe it really _is_ a sound problem.

Mark - can you verify that you don't have any DRM support in your kernel?

Frederic, Takashi, did that bug-report ever get resolved?

Linus
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