https://github.com/torvalds/linux
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
Raw File
Tip revision: 6946bd636364effce06ea46fe8f8cd6e2edb004e authored by Peter Zijlstra on 27 August 2006, 08:23:31 UTC
[PATCH] lockdep: fix blkdev_open() warning
Tip revision: 6946bd6
REPORTING-BUGS
[Some of this is taken from Frohwalt Egerer's original linux-kernel FAQ]

     What follows is a suggested procedure for reporting Linux bugs. You
aren't obliged to use the bug reporting format, it is provided as a guide
to the kind of information that can be useful to developers - no more.

     If the failure includes an "OOPS:" type message in your log or on
screen please read "Documentation/oops-tracing.txt" before posting your
bug report. This explains what you should do with the "Oops" information
to make it useful to the recipient.

      Send the output to the maintainer of the kernel area that seems to
be involved with the problem. Don't worry too much about getting the
wrong person. If you are unsure send it to the person responsible for the
code relevant to what you were doing. If it occurs repeatably try and
describe how to recreate it. That is worth even more than the oops itself.
The list of maintainers is in the MAINTAINERS file in this directory.

      If it is a security bug, please copy the Security Contact listed
in the MAINTAINERS file.  They can help coordinate bugfix and disclosure.
See Documentation/SecurityBugs for more information.

      If you are totally stumped as to whom to send the report, send it to
linux-kernel@vger.kernel.org. (For more information on the linux-kernel
mailing list see http://www.tux.org/lkml/).

This is a suggested format for a bug report sent to the Linux kernel mailing
list. Having a standardized bug report form makes it easier for you not to
overlook things, and easier for the developers to find the pieces of
information they're really interested in. Don't feel you have to follow it.

      First run the ver_linux script included as scripts/ver_linux, which
reports the version of some important subsystems.  Run this script with
the command "sh scripts/ver_linux".

Use that information to fill in all fields of the bug report form, and
post it to the mailing list with a subject of "PROBLEM: <one line
summary from [1.]>" for easy identification by the developers.

[1.] One line summary of the problem:
[2.] Full description of the problem/report:
[3.] Keywords (i.e., modules, networking, kernel):
[4.] Kernel version (from /proc/version):
[5.] Most recent kernel version which did not have the bug:
[6.] Output of Oops.. message (if applicable) with symbolic information
     resolved (see Documentation/oops-tracing.txt)
[7.] A small shell script or example program which triggers the
     problem (if possible)
[8.] Environment
[8.1.] Software (add the output of the ver_linux script here)
[8.2.] Processor information (from /proc/cpuinfo):
[8.3.] Module information (from /proc/modules):
[8.4.] Loaded driver and hardware information (/proc/ioports, /proc/iomem)
[8.5.] PCI information ('lspci -vvv' as root)
[8.6.] SCSI information (from /proc/scsi/scsi)
[8.7.] Other information that might be relevant to the problem
       (please look in /proc and include all information that you
       think to be relevant):
[X.] Other notes, patches, fixes, workarounds:


Thank you
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