Re: Re: [Bug] possible circular locking in reiserfs_unpack

From: Jarek Poplawski
Date: Thu Sep 09 2010 - 10:55:52 EST

Frederic Weisbecker wrote, On 12/23/-28158 08:59 PM:

> On Wed, Sep 08, 2010 at 03:37:30PM -0700, Andrew Morton wrote:
>> On Sun, 5 Sep 2010 13:31:21 +0200
>> Jarek Poplawski <jarkao2@xxxxxxxxx> wrote:
>>
>>> Hi,
>>> I get this warning on every lilo write with 2.6.35.4 and a bit/git
>>> later too.
>>>
>> Can you tell us the latest kernel version which did *not* have this
>> bug? That way we can narrow the problem down a bit.
>>
>> Thanks.
>
>
>
> Ah, when you see &REISERFS_SB(s)->lock in a bug report, don't hesitate to blame me :-)
>
> This is a problem resulting from the bkl conversion to a mutex that introduced
> a lot of new locking dependencies. Most of them have been fixed, but for less
> tested paths like ioctl, we hear about it later.
>
> Does the following patch fixes the issue?
> If so, I'll make a proper changelog and put the appropriate 2.6.33-35 stable
> tags for the backport.
>
> Thnaks!
>
>
> diff --git a/fs/reiserfs/ioctl.c b/fs/reiserfs/ioctl.c
> index f53505d..679d502 100644
> --- a/fs/reiserfs/ioctl.c
> +++ b/fs/reiserfs/ioctl.c
> @@ -188,7 +188,7 @@ int reiserfs_unpack(struct inode *inode, struct file *filp)
> /* we need to make sure nobody is changing the file size beneath
> ** us
> */
> - mutex_lock(&inode->i_mutex);
> + reiserfs_mutex_lock_safe(&inode->i_mutex, inode->i_sb);
> reiserfs_write_lock(inode->i_sb);
>
> write_from = inode->i_size & (blocksize - 1);
>


So, there is still a warning but a bit different now.

Jarek P.

[ 67.110273] =======================================================
[ 67.110313] [ INFO: possible circular locking dependency detected ]
[ 67.110313] 2.6.35.4.4a #3
[ 67.110313] -------------------------------------------------------
[ 67.110313] lilo/1620 is trying to acquire lock:
[ 67.110313] (&journal->j_mutex){+.+...}, at: [<d0325bff>] do_journal_begin_r+0x7f/0x340 [reiserfs]
[ 67.110313]
[ 67.110313] but task is already holding lock:
[ 67.110313] (&REISERFS_SB(s)->lock){+.+.+.}, at: [<d032a278>] reiserfs_write_lock+0x28/0x40 [reiserfs]
[ 67.110313]
[ 67.110313] which lock already depends on the new lock.
[ 67.110313]
[ 67.110313]
[ 67.110313] the existing dependency chain (in reverse order) is:
[ 67.110313]
[ 67.110313] -> #1 (&REISERFS_SB(s)->lock){+.+.+.}:
[ 67.110313] [<c10562b7>] lock_acquire+0x67/0x80
[ 67.110313] [<c12facad>] __mutex_lock_common+0x4d/0x410
[ 67.110313] [<c12fb0c8>] mutex_lock_nested+0x18/0x20
[ 67.110313] [<d032a278>] reiserfs_write_lock+0x28/0x40 [reiserfs]
[ 67.110313] [<d0325c06>] do_journal_begin_r+0x86/0x340 [reiserfs]
[ 67.110313] [<d0325f77>] journal_begin+0x77/0x140 [reiserfs]
[ 67.110313] [<d0315be4>] reiserfs_remount+0x224/0x530 [reiserfs]
[ 67.110313] [<c10b6a20>] do_remount_sb+0x60/0x110
[ 67.110313] [<c10cee25>] do_mount+0x625/0x790
[ 67.110313] [<c10cf014>] sys_mount+0x84/0xb0
[ 67.110313] [<c12fca3d>] syscall_call+0x7/0xb
[ 67.110313]
[ 67.110313] -> #0 (&journal->j_mutex){+.+...}:
[ 67.110313] [<c10560f6>] __lock_acquire+0x1026/0x1180
[ 67.110313] [<c10562b7>] lock_acquire+0x67/0x80
[ 67.110313] [<c12facad>] __mutex_lock_common+0x4d/0x410
[ 67.110313] [<c12fb0c8>] mutex_lock_nested+0x18/0x20
[ 67.110313] [<d0325bff>] do_journal_begin_r+0x7f/0x340 [reiserfs]
[ 67.110313] [<d0325f77>] journal_begin+0x77/0x140 [reiserfs]
[ 67.110313] [<d0326271>] reiserfs_persistent_transaction+0x41/0x90 [reiserfs]
[ 67.110313] [<d030d06c>] reiserfs_get_block+0x22c/0x1530 [reiserfs]
[ 67.110313] [<c10db9db>] __block_prepare_write+0x1bb/0x3a0
[ 67.110313] [<c10dbbe6>] block_prepare_write+0x26/0x40
[ 67.110313] [<d030b738>] reiserfs_prepare_write+0x88/0x170 [reiserfs]
[ 67.110313] [<d03294d6>] reiserfs_unpack+0xe6/0x120 [reiserfs]
[ 67.110313] [<d0329782>] reiserfs_ioctl+0x272/0x320 [reiserfs]
[ 67.110313] [<c10c3188>] vfs_ioctl+0x28/0xa0
[ 67.110313] [<c10c3bbd>] do_vfs_ioctl+0x32d/0x5c0
[ 67.110313] [<c10c3eb3>] sys_ioctl+0x63/0x70
[ 67.110313] [<c12fca3d>] syscall_call+0x7/0xb
[ 67.110313]
[ 67.110313] other info that might help us debug this:
[ 67.110313]
[ 67.110313] 2 locks held by lilo/1620:
[ 67.110313] #0: (&sb->s_type->i_mutex_key#8){+.+.+.}, at: [<d032945a>] reiserfs_unpack+0x6a/0x120 [reiserfs]
[ 67.110313] #1: (&REISERFS_SB(s)->lock){+.+.+.}, at: [<d032a278>] reiserfs_write_lock+0x28/0x40 [reiserfs]
[ 67.110313]
[ 67.110313] stack backtrace:
[ 67.110313] Pid: 1620, comm: lilo Not tainted 2.6.35.4.4a #3
[ 67.110313] Call Trace:
[ 67.110313] [<c12f9aba>] ? printk+0x18/0x1e
[ 67.110313] [<c1054182>] print_circular_bug+0xd2/0xe0
[ 67.110313] [<c10560f6>] __lock_acquire+0x1026/0x1180
[ 67.110313] [<c10562b7>] lock_acquire+0x67/0x80
[ 67.110313] [<d0325bff>] ? do_journal_begin_r+0x7f/0x340 [reiserfs]
[ 67.110313] [<c12facad>] __mutex_lock_common+0x4d/0x410
[ 67.110313] [<d0325bff>] ? do_journal_begin_r+0x7f/0x340 [reiserfs]
[ 67.110313] [<c1055275>] ? __lock_acquire+0x1a5/0x1180
[ 67.110313] [<c10897ae>] ? mempool_alloc_slab+0xe/0x10
[ 67.110313] [<c12fb0c8>] mutex_lock_nested+0x18/0x20
[ 67.110313] [<d0325bff>] ? do_journal_begin_r+0x7f/0x340 [reiserfs]
[ 67.110313] [<d0325bff>] do_journal_begin_r+0x7f/0x340 [reiserfs]
[ 67.110313] [<c1054bd2>] ? mark_held_locks+0x62/0x80
[ 67.110313] [<c10b163d>] ? kmem_cache_alloc+0x7d/0xb0
[ 67.110313] [<c1054e5c>] ? trace_hardirqs_on_caller+0x11c/0x160
[ 67.110313] [<d0325f77>] journal_begin+0x77/0x140 [reiserfs]
[ 67.110313] [<d0326262>] ? reiserfs_persistent_transaction+0x32/0x90 [reiserfs]
[ 67.110313] [<d0326271>] reiserfs_persistent_transaction+0x41/0x90 [reiserfs]
[ 67.110313] [<d030d06c>] reiserfs_get_block+0x22c/0x1530 [reiserfs]
[ 67.110313] [<c1055275>] ? __lock_acquire+0x1a5/0x1180
[ 67.110313] [<c12fc672>] ? _raw_spin_unlock_irq+0x22/0x50
[ 67.110313] [<c10b163d>] ? kmem_cache_alloc+0x7d/0xb0
[ 67.110313] [<c1054e5c>] ? trace_hardirqs_on_caller+0x11c/0x160
[ 67.110313] [<c102789b>] ? sub_preempt_count+0x7b/0xb0
[ 67.110313] [<c12fc457>] ? _raw_spin_unlock+0x27/0x40
[ 67.110313] [<c10db9db>] __block_prepare_write+0x1bb/0x3a0
[ 67.110313] [<c10dbbe6>] block_prepare_write+0x26/0x40
[ 67.110313] [<d030ce40>] ? reiserfs_get_block+0x0/0x1530 [reiserfs]
[ 67.110313] [<d030b738>] reiserfs_prepare_write+0x88/0x170 [reiserfs]
[ 67.110313] [<d030ce40>] ? reiserfs_get_block+0x0/0x1530 [reiserfs]
[ 67.110313] [<d03294d6>] reiserfs_unpack+0xe6/0x120 [reiserfs]
[ 67.110313] [<d0329782>] reiserfs_ioctl+0x272/0x320 [reiserfs]
[ 67.110313] [<d0329510>] ? reiserfs_ioctl+0x0/0x320 [reiserfs]
[ 67.110313] [<c10c3188>] vfs_ioctl+0x28/0xa0
[ 67.110313] [<c10c3bbd>] do_vfs_ioctl+0x32d/0x5c0
[ 67.110313] [<c109a228>] ? might_fault+0x88/0x90
[ 67.110313] [<c109a1e2>] ? might_fault+0x42/0x90
[ 67.110313] [<c10b6588>] ? fget_light+0xf8/0x2f0
[ 67.110313] [<c10c3eb3>] sys_ioctl+0x63/0x70
[ 67.110313] [<c12fca3d>] syscall_call+0x7/0xb
[ 67.110313] [<c12f007b>] ? cookie_v6_check+0x44b/0x630

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