Re: ext4 lockdep trace (3.1.0rc3)

Tao Ma
2011-08-30T10:23:22Z

Hi Dave,
On 08/30/2011 04:54 AM, Dave Jones wrote:
> On Mon, Aug 29, 2011 at 04:48:30PM -0400, Dave Jones wrote:
> > On Fri, Aug 26, 2011 at 05:49:30PM -0400, Dave Jones wrote:
> > > just hit this while building a kernel. Laptop wedged for a few seconds
> > > during the final link, and this was in the log when it unwedged.
> >
> > I still see this in rc4, and can reproduce it reliably every time I build.
> > It only started happening in the last week. I don't see any ext4 or vfs commits
> > within a few days of that, so I'm not sure why it only just begun
> > (I do daily builds, and the 26th was the first time I saw it appear)
> >
> > Given the lack of obvious commits in that timeframe, I'm not sure a bisect is
> > going to be particularly fruitful. It might just be that my IO patterns changed ?
>
> also a second variant with a different trace.
Ted has sent out a fix in the ext4 mailist. Please search for the subject:
[URGENT PATCH] ext4: fix potential deadlock in ext4_evict_inode()

Thanks
Tao
>
> Dave
>
>
> =======================================================
> [ INFO: possible circular locking dependency detected ]
> 3.1.0-rc3+ #151
> -------------------------------------------------------
> gnome-settings-/2037 is trying to acquire lock:
> (&sb->s_type->i_mutex_key#14){+.+.+.}, at: [<ffffffff811cee83>] ext4_evict_inode+0x76/0x33c
>
> but task is already holding lock:
> (&mm->mmap_sem){++++++}, at: [<ffffffff8111ba13>] sys_munmap+0x3b/0x60
>
> which lock already depends on the new lock.
>
>
> the existing dependency chain (in reverse order) is:
>
> -> #1 (&mm->mmap_sem){++++++}:
> [<ffffffff81091251>] lock_acquire+0xf3/0x13e
> [<ffffffff8111499a>] might_fault+0x80/0xa3
> [<ffffffff811570ef>] filldir+0x6f/0xc7
> [<ffffffff811c5c3f>] call_filldir+0x96/0xc0
> [<ffffffff811c5f78>] ext4_readdir+0x1bd/0x548
> [<ffffffff81157344>] vfs_readdir+0x7b/0xb4
> [<ffffffff81157463>] sys_getdents+0x7e/0xd1
> [<ffffffff814f2342>] system_call_fastpath+0x16/0x1b
>
> -> #0 (&sb->s_type->i_mutex_key#14){+.+.+.}:
> [<ffffffff81090a71>] __lock_acquire+0xa2f/0xd0c
> [<ffffffff81091251>] lock_acquire+0xf3/0x13e
> [<ffffffff814ea40d>] __mutex_lock_common+0x65/0x44a
> [<ffffffff814ea8ed>] mutex_lock_nested+0x3b/0x40
> [<ffffffff811cee83>] ext4_evict_inode+0x76/0x33c
> [<ffffffff8115d2a5>] evict+0x98/0x152
> [<ffffffff8115d4f0>] iput+0x191/0x199
> [<ffffffff8115a0f2>] dentry_kill+0x123/0x145
> [<ffffffff8115a4fc>] dput+0xf2/0x102
> [<ffffffff8114948a>] fput+0x1d8/0x1f0
> [<ffffffff8111a6bd>] remove_vma+0x51/0x82
> [<ffffffff8111b8a0>] do_munmap+0x2f2/0x30b
> [<ffffffff8111ba21>] sys_munmap+0x49/0x60
> [<ffffffff814f2342>] 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 ***
>
> 1 lock held by gnome-settings-/2037:
> #0: (&mm->mmap_sem){++++++}, at: [<ffffffff8111ba13>] sys_munmap+0x3b/0x60
>
> stack backtrace:
> Pid: 2037, comm: gnome-settings- Not tainted 3.1.0-rc3+ #151
> Call Trace:
> [<ffffffff810811d1>] ? up+0x39/0x3e
> [<ffffffff814e1469>] print_circular_bug+0x1f8/0x209
> [<ffffffff81090a71>] __lock_acquire+0xa2f/0xd0c
> [<ffffffff810821ef>] ? local_clock+0x35/0x4c
> [<ffffffff8108fe4f>] ? mark_lock+0x2d/0x220
> [<ffffffff811cee83>] ? ext4_evict_inode+0x76/0x33c
> [<ffffffff81091251>] lock_acquire+0xf3/0x13e
> [<ffffffff811cee83>] ? ext4_evict_inode+0x76/0x33c
> [<ffffffff814ea3e5>] ? __mutex_lock_common+0x3d/0x44a
> [<ffffffff814ea8ed>] ? mutex_lock_nested+0x3b/0x40
> [<ffffffff811cee83>] ? ext4_evict_inode+0x76/0x33c
> [<ffffffff814ea40d>] __mutex_lock_common+0x65/0x44a
> [<ffffffff811cee83>] ? ext4_evict_inode+0x76/0x33c
> [<ffffffff810821ef>] ? local_clock+0x35/0x4c
> [<ffffffff8115d297>] ? evict+0x8a/0x152
> [<ffffffff8108d9ba>] ? put_lock_stats+0xe/0x29
> [<ffffffff8108e03e>] ? lock_release_holdtime.part.10+0x59/0x62
> [<ffffffff8115d297>] ? evict+0x8a/0x152
> [<ffffffff814ea8ed>] mutex_lock_nested+0x3b/0x40
> [<ffffffff811cee83>] ext4_evict_inode+0x76/0x33c
> [<ffffffff8115d2a5>] evict+0x98/0x152
> [<ffffffff8115d4f0>] iput+0x191/0x199
> [<ffffffff8115a0f2>] dentry_kill+0x123/0x145
> [<ffffffff8115a4fc>] dput+0xf2/0x102
> [<ffffffff8114948a>] fput+0x1d8/0x1f0
> [<ffffffff8111a6bd>] remove_vma+0x51/0x82
> [<ffffffff8111b8a0>] do_munmap+0x2f2/0x30b
> [<ffffffff8111ba21>] sys_munmap+0x49/0x60
> [<ffffffff814f2342>] system_call_fastpath+0x16/0x1b
>
> --
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