Messages in this thread | | | Date | Tue, 23 Aug 2011 21:49:31 +1000 | From | Dave Chinner <> | Subject | Re: 3.1.0-rc3 -- INFO: possible circular locking dependency detected |
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On Tue, Aug 23, 2011 at 07:35:00AM -0400, Josh Boyer wrote: > On Tue, Aug 23, 2011 at 12:39 AM, Miles Lane <miles.lane@gmail.com> wrote: > > [ INFO: possible circular locking dependency detected ] > > 3.1.0-rc3 #2 > > ------------------------------------------------------- > > dconf-service/1836 is trying to acquire lock: > > (&sb->s_type->i_mutex_key#12){+.+.+.}, at: [<ffffffff8116df1a>] > > ext4_evict_inode+0x88/0x32b > > > > but task is already holding lock: > > (&mm->mmap_sem){++++++}, at: [<ffffffff810d4393>] sys_munmap+0x36/0x5b > > > > which lock already depends on the new lock. > > > > the existing dependency chain (in reverse order) is: > > > > -> #1 (&mm->mmap_sem){++++++}: > > [<ffffffff8106933a>] lock_acquire+0x129/0x14e > > [<ffffffff810cddbd>] might_fault+0x68/0x8b > > [<ffffffff810fcf5e>] filldir+0x6a/0xc2 > > [<ffffffff811651a1>] call_filldir+0x91/0xb8 > > [<ffffffff811654bf>] ext4_readdir+0x1af/0x510 > > [<ffffffff810fd1a4>] vfs_readdir+0x76/0xac > > [<ffffffff810fd2b6>] sys_getdents+0x79/0xc9 > > [<ffffffff814162fb>] system_call_fastpath+0x16/0x1b > > > > -> #0 (&sb->s_type->i_mutex_key#12){+.+.+.}: > > [<ffffffff81068b10>] __lock_acquire+0xa5e/0xd52 > > [<ffffffff8106933a>] lock_acquire+0x129/0x14e > > [<ffffffff8140f1a2>] __mutex_lock_common+0x64/0x413 > > [<ffffffff8140f5b0>] mutex_lock_nested+0x16/0x18 > > [<ffffffff8116df1a>] ext4_evict_inode+0x88/0x32b > > [<ffffffff81102d8a>] evict+0x94/0x14e > > [<ffffffff81102fd0>] iput+0x18c/0x195 > > [<ffffffff810ffdd4>] dentry_kill+0x11e/0x140 > > [<ffffffff8110019b>] dput+0xd4/0xe4 > > [<ffffffff810efac3>] fput+0x1a5/0x1bd > > [<ffffffff810d3214>] remove_vma+0x37/0x5f > > [<ffffffff810d4239>] do_munmap+0x2ed/0x306 > > [<ffffffff810d43a1>] sys_munmap+0x44/0x5b > > [<ffffffff814162fb>] system_call_fastpath+0x16/0x1b > > > > other info that might help us debug this: > > > > Possible unsafe locking scenario: > > > > CPU0 CPU1 > > ---- ---- > > lock(&mm->mmap_sem); > > lock(&sb->s_type->i_mutex_key); > > lock(&mm->mmap_sem); > > lock(&sb->s_type->i_mutex_key); > > > > *** DEADLOCK *** > > This one was reported yesterday: https://lkml.org/lkml/2011/8/21/163 > and we're hoping Ted (or someone else from the ext4 camp) can comment > on why ext4_evict_inode is holding i_mutex.
Actually, the problem has nothing to do with ext4. the problem is that remove_vma() is holding the mmap_sem while calling fput(). The correct locking order is i_mutex->mmap_sem, as documented in mm/filemap.c:
* ->i_mutex (generic_file_buffered_write) * ->mmap_sem (fault_in_pages_readable->do_page_fault)
The way remove_vma() calls fput() also triggers lockdep reports in XFS and it will do so with any filesystem that takes an inode specific lock in it's evict() processing. IOWs, remove_vma() needs fixing, not ext4....
Cheers,
Dave. -- Dave Chinner david@fromorbit.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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