linux-kernel - Re: [possible deadlock][3.1.0-g138c4ae] possible circular locking dependency detected

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Message-ID: <CAA_GA1cKK45Z=YFUHRi-LUuhWpcs9ruW9xom_6LRmqhRNao+hQ@mail.gmail.com>
Date:	Fri, 28 Oct 2011 14:02:56 +0800
From:	Bob Liu <lliubbo@...il.com>
To:	gaowanlong@...fujitsu.com
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	linux-fsdevel@...r.kernel.org, Linux-MM <linux-mm@...ck.org>
Subject: Re: [possible deadlock][3.1.0-g138c4ae] possible circular locking
 dependency detected

On Fri, Oct 28, 2011 at 1:49 PM, Wanlong Gao <gaowanlong@...fujitsu.com> wrote:
> On 10/28/2011 01:44 PM, Bob Liu wrote:
>
>> On Fri, Oct 28, 2011 at 11:42 AM, Wanlong Gao <gaowanlong@...fujitsu.com> wrote:
>>> Hi folks:
>>>
>>> My dmesg said that:
>>>
>>> ======================================================
>>> [ INFO: possible circular locking dependency detected ]
>>> 3.1.0-138c4ae #2
>>> -------------------------------------------------------
>>> hugemmap05/18198 is trying to acquire lock:
>>>  (&mm->mmap_sem){++++++}, at: [<ffffffff8114d85c>] might_fault+0x5c/0xb0
>>>
>>> but task is already holding lock:
>>>  (&sb->s_type->i_mutex_key#21){+.+.+.}, at: [<ffffffff811a10f6>] vfs_readdir+0x86/0xe0
>>>
>>> which lock already depends on the new lock.
>>>
>>>
>>> the existing dependency chain (in reverse order) is:
>>>
>>> -> #1 (&sb->s_type->i_mutex_key#21){+.+.+.}:
>>>       [<ffffffff810afd34>] validate_chain+0x704/0x860
>>>       [<ffffffff810b018c>] __lock_acquire+0x2fc/0x500
>>>       [<ffffffff810b0b01>] lock_acquire+0xb1/0x1a0
>>>       [<ffffffff815464f2>] __mutex_lock_common+0x62/0x420
>>>       [<ffffffff81546a1a>] mutex_lock_nested+0x4a/0x60
>>>       [<ffffffff8120b4ba>] hugetlbfs_file_mmap+0xaa/0x160
>>>       [<ffffffff81158071>] mmap_region+0x3e1/0x590
>>>       [<ffffffff81158584>] do_mmap_pgoff+0x364/0x3b0
>>>       [<ffffffff811587d9>] sys_mmap_pgoff+0x209/0x240
>>>       [<ffffffff8101aac9>] sys_mmap+0x29/0x30
>>>       [<ffffffff81551542>] system_call_fastpath+0x16/0x1b
>>>
>>> -> #0 (&mm->mmap_sem){++++++}:
>>>       [<ffffffff810af607>] check_prev_add+0x537/0x560
>>>       [<ffffffff810afd34>] validate_chain+0x704/0x860
>>>       [<ffffffff810b018c>] __lock_acquire+0x2fc/0x500
>>>       [<ffffffff810b0b01>] lock_acquire+0xb1/0x1a0
>>>       [<ffffffff8114d889>] might_fault+0x89/0xb0
>>>       [<ffffffff811a0f2e>] filldir+0x7e/0xe0
>>>       [<ffffffff811b445e>] dcache_readdir+0x5e/0x230
>>>       [<ffffffff811a1130>] vfs_readdir+0xc0/0xe0
>>>       [<ffffffff811a12c9>] sys_getdents+0x89/0x100
>>>       [<ffffffff81551542>] system_call_fastpath+0x16/0x1b
>>>
>>> other info that might help us debug this:
>>>
>>>  Possible unsafe locking scenario:
>>>
>>>       CPU0                    CPU1
>>>       ----                    ----
>>>  lock(&sb->s_type->i_mutex_key);
>>>                               lock(&mm->mmap_sem);
>>>                               lock(&sb->s_type->i_mutex_key);
>>>  lock(&mm->mmap_sem);
>>>
>>>  *** DEADLOCK ***
>>>
>>> 1 lock held by hugemmap05/18198:
>>>  #0:  (&sb->s_type->i_mutex_key#21){+.+.+.}, at: [<ffffffff811a10f6>] vfs_readdir+0x86/0xe0
>>>
>>> stack backtrace:
>>> Pid: 18198, comm: hugemmap05 Not tainted 3.1.0-138c4ae #2
>>> Call Trace:
>>>  [<ffffffff810ad469>] print_circular_bug+0x109/0x110
>>>  [<ffffffff810af607>] check_prev_add+0x537/0x560
>>>  [<ffffffff8114e112>] ? do_anonymous_page+0xf2/0x2d0
>>>  [<ffffffff810afd34>] validate_chain+0x704/0x860
>>>  [<ffffffff810b018c>] __lock_acquire+0x2fc/0x500
>>>  [<ffffffff810b0b01>] lock_acquire+0xb1/0x1a0
>>>  [<ffffffff8114d85c>] ? might_fault+0x5c/0xb0
>>>  [<ffffffff8114d889>] might_fault+0x89/0xb0
>>>  [<ffffffff8114d85c>] ? might_fault+0x5c/0xb0
>>>  [<ffffffff81546763>] ? __mutex_lock_common+0x2d3/0x420
>>>  [<ffffffff811a10f6>] ? vfs_readdir+0x86/0xe0
>>>  [<ffffffff811a0f2e>] filldir+0x7e/0xe0
>>>  [<ffffffff811b445e>] dcache_readdir+0x5e/0x230
>>>  [<ffffffff811a0eb0>] ? filldir64+0xf0/0xf0
>>>  [<ffffffff811a0eb0>] ? filldir64+0xf0/0xf0
>>>  [<ffffffff811a0eb0>] ? filldir64+0xf0/0xf0
>>>  [<ffffffff811a1130>] vfs_readdir+0xc0/0xe0
>>>  [<ffffffff8118e9be>] ? fget+0xee/0x220
>>>  [<ffffffff8118e8d0>] ? fget_raw+0x220/0x220
>>>  [<ffffffff811a12c9>] sys_getdents+0x89/0x100
>>>  [<ffffffff81551542>] system_call_fastpath+0x16/0x1b
>>>
>>
>> Please try this patch "lockdep: Add helper function for dir vs file
>> i_mutex annotation" by josh.
>> http://git.kernel.org/?p=linux/kernel/git/next/linux-next.git;a=commitdiff;h=e096d0c7e2e4e5893792db865dd065ac73cf1f00
>>
>
>
> Oh, it looks like can fix this bug, but I also can't reproduce it whether with or without this patch.
>

Make sure CONFIG_DEBUG_LOCK_ALLOC was set.

-- 
Regards,
--Bob
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