Revision 6946bd636364effce06ea46fe8f8cd6e2edb004e authored by Peter Zijlstra on 27 August 2006, 08:23:31 UTC, committed by Linus Torvalds on 27 August 2006, 18:01:29 UTC
On Wed, 2006-08-09 at 07:57 +0200, Rolf Eike Beer wrote:
> =============================================
> [ INFO: possible recursive locking detected ]
> ---------------------------------------------
> parted/7929 is trying to acquire lock:
> (&bdev->bd_mutex){--..}, at: [<c105eb8d>] __blkdev_put+0x1e/0x13c
>
> but task is already holding lock:
> (&bdev->bd_mutex){--..}, at: [<c105eec6>] do_open+0x72/0x3a8
>
> other info that might help us debug this:
> 1 lock held by parted/7929:
> #0: (&bdev->bd_mutex){--..}, at: [<c105eec6>] do_open+0x72/0x3a8
> stack backtrace:
> [<c1003aad>] show_trace_log_lvl+0x58/0x15b
> [<c100495f>] show_trace+0xd/0x10
> [<c1004979>] dump_stack+0x17/0x1a
> [<c102dee5>] __lock_acquire+0x753/0x99c
> [<c102e3b0>] lock_acquire+0x4a/0x6a
> [<c1204501>] mutex_lock_nested+0xc8/0x20c
> [<c105eb8d>] __blkdev_put+0x1e/0x13c
> [<c105ecc4>] blkdev_put+0xa/0xc
> [<c105f18a>] do_open+0x336/0x3a8
> [<c105f21b>] blkdev_open+0x1f/0x4c
> [<c1057b40>] __dentry_open+0xc7/0x1aa
> [<c1057c91>] nameidata_to_filp+0x1c/0x2e
> [<c1057cd1>] do_filp_open+0x2e/0x35
> [<c1057dd7>] do_sys_open+0x38/0x68
> [<c1057e33>] sys_open+0x16/0x18
> [<c1002845>] sysenter_past_esp+0x56/0x8d
OK, I'm having a look here; its all new to me so bear with me.
blkdev_open() calls
do_open(bdev, ...,BD_MUTEX_NORMAL) and takes
mutex_lock_nested(&bdev->bd_mutex, BD_MUTEX_NORMAL)
then something fails, and we're thrown to:
out_first: where
if (bdev != bdev->bd_contains)
blkdev_put(bdev->bd_contains) which is
__blkdev_put(bdev->bd_contains, BD_MUTEX_NORMAL) which does
mutex_lock_nested(&bdev->bd_contains->bd_mutex, BD_MUTEX_NORMAL) <--- lockdep trigger
When going to out_first, dbev->bd_contains is either bdev or whole, and
since we take the branch it must be whole. So it seems to me the
following patch would be the right one:
[akpm@osdl.org: compile fix]
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Acked-by: NeilBrown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
1 parent 7334bb4
unaligned.h
#ifndef __X8664_UNALIGNED_H
#define __X8664_UNALIGNED_H
/*
* The x86-64 can do unaligned accesses itself.
*
* The strange macros are there to make sure these can't
* be misused in a way that makes them not work on other
* architectures where unaligned accesses aren't as simple.
*/
/**
* get_unaligned - get value from possibly mis-aligned location
* @ptr: pointer to value
*
* This macro should be used for accessing values larger in size than
* single bytes at locations that are expected to be improperly aligned,
* e.g. retrieving a u16 value from a location not u16-aligned.
*
* Note that unaligned accesses can be very expensive on some architectures.
*/
#define get_unaligned(ptr) (*(ptr))
/**
* put_unaligned - put value to a possibly mis-aligned location
* @val: value to place
* @ptr: pointer to location
*
* This macro should be used for placing values larger in size than
* single bytes at locations that are expected to be improperly aligned,
* e.g. writing a u16 value to a location not u16-aligned.
*
* Note that unaligned accesses can be very expensive on some architectures.
*/
#define put_unaligned(val, ptr) ((void)( *(ptr) = (val) ))
#endif
Computing file changes ...
