On Mon, 7 Nov 2011 22:37:57 +0100 (CET)
Thomas Gleixner <tglx@linutronix.de> wrote:

> Dear RT Folks,
> 
> I'm pleased to announce the 3.0.8-rt21 release.
> 
>

Thomas et al, 

Got the following splat on boot (f15 64-bit laptop, quad-core i7):

[  146.609030] 
[  146.609031] =======================================================
[  146.609033] [ INFO: possible circular locking dependency detected ]
[  146.609035] 3.0.8-rt22+ #27
[  146.609036] -------------------------------------------------------
[  146.609038] dconf-service/9046 is trying to acquire lock:
[  146.609040]  (&sb->s_type->i_mutex_key#13){+.+.+.}, at: [<ffffffff811adcc4>] ext4_evict_inode+0x44/0x26f
[  146.609047] 
[  146.609048] but task is already holding lock:
[  146.609049]  (&mm->mmap_sem){++++++}, at: [<ffffffff81108ee6>] sys_munmap+0x36/0x5b
[  146.609053] 
[  146.609054] which lock already depends on the new lock.
[  146.609055] 
[  146.609056] 
[  146.609056] the existing dependency chain (in reverse order) is:
[  146.609058] 
[  146.609058] -> #1 (&mm->mmap_sem){++++++}:
[  146.609061]        [<ffffffff810844f0>] check_prevs_add+0x8b/0x104
[  146.609065]        [<ffffffff810848ca>] validate_chain+0x361/0x39d
[  146.609067]        [<ffffffff81084fa5>] __lock_acquire+0x37a/0x3f3
[  146.609069]        [<ffffffff81085501>] lock_acquire+0xc4/0x108
[  146.609071]        [<ffffffff811026a7>] might_fault+0x6d/0x90
[  146.609075]        [<ffffffff8113eac7>] filldir+0x6f/0xc7
[  146.609079]        [<ffffffff811a377b>] call_filldir+0x96/0xc0
[  146.609081]        [<ffffffff811a3937>] ext4_dx_readdir+0x17d/0x1e6
[  146.609083]        [<ffffffff811a3b4d>] ext4_readdir+0x70/0x3b3
[  146.609085]        [<ffffffff8113ed1d>] vfs_readdir+0x7c/0xb5
[  146.609087]        [<ffffffff8113ee3c>] sys_getdents+0x7e/0xd1
[  146.609089]        [<ffffffff814cc2c2>] system_call_fastpath+0x16/0x1b
[  146.609094] 
[  146.609094] -> #0 (&sb->s_type->i_mutex_key#13){+.+.+.}:
[  146.609096]        [<ffffffff810842c6>] check_prev_add+0x68/0x207
[  146.609098]        [<ffffffff810844f0>] check_prevs_add+0x8b/0x104
[  146.609101]        [<ffffffff810848ca>] validate_chain+0x361/0x39d
[  146.609103]        [<ffffffff81084fa5>] __lock_acquire+0x37a/0x3f3
[  146.609105]        [<ffffffff81085501>] lock_acquire+0xc4/0x108
[  146.609108]        [<ffffffff814c5854>] _mutex_lock+0x31/0x40
[  146.609113]        [<ffffffff811adcc4>] ext4_evict_inode+0x44/0x26f
[  146.609120]        [<ffffffff811452b7>] evict+0x89/0x141
[  146.609123]        [<ffffffff81145501>] iput_final+0x14d/0x155
[  146.609126]        [<ffffffff81145543>] iput+0x3a/0x3e
[  146.609128]        [<ffffffff81140b61>] dentry_iput+0x97/0xaf
[  146.609130]        [<ffffffff81141e89>] dentry_kill+0xc7/0xde
[  146.609133]        [<ffffffff81142444>] dput+0xe3/0xf4
[  146.609135]        [<ffffffff8113157d>] __fput+0x1a9/0x1c1
[  146.609137]        [<ffffffff811315b2>] fput+0x1d/0x1f
[  146.609139]        [<ffffffff81107bb1>] remove_vma+0x3c/0x71
[  146.609141]        [<ffffffff81108d78>] do_munmap+0x267/0x280
[  146.609143]        [<ffffffff81108ef4>] sys_munmap+0x44/0x5b
[  146.609145]        [<ffffffff814cc2c2>] system_call_fastpath+0x16/0x1b
[  146.609148] 
[  146.609149] other info that might help us debug this:
[  146.609150] 
[  146.609151]  Possible unsafe locking scenario:
[  146.609151] 
[  146.609152]        CPU0                    CPU1
[  146.609153]        ----                    ----
[  146.609154]   lock(&mm->mmap_sem);
[  146.609155]                                lock(&sb->s_type->i_mutex_key);
[  146.609157]                                lock(&mm->mmap_sem);
[  146.609158]   lock(&sb->s_type->i_mutex_key);
[  146.609159] 
[  146.609160]  *** DEADLOCK ***
[  146.609160] 
[  146.609162] 1 lock held by dconf-service/9046:
[  146.609163]  #0:  (&mm->mmap_sem){++++++}, at: [<ffffffff81108ee6>] sys_munmap+0x36/0x5b
[  146.609166] 
[  146.609166] stack backtrace:
[  146.609168] Pid: 9046, comm: dconf-service Not tainted 3.0.8-rt22+ #27
[  146.609169] Call Trace:
[  146.609174]  [<ffffffff814b1fd1>] print_circular_bug+0xc8/0xd9
[  146.609176]  [<ffffffff810842c6>] check_prev_add+0x68/0x207
[  146.609179]  [<ffffffff810844f0>] check_prevs_add+0x8b/0x104
[  146.609182]  [<ffffffff810848ca>] validate_chain+0x361/0x39d
[  146.609184]  [<ffffffff81084fa5>] __lock_acquire+0x37a/0x3f3
[  146.609187]  [<ffffffff811adcc4>] ? ext4_evict_inode+0x44/0x26f
[  146.609189]  [<ffffffff81085501>] lock_acquire+0xc4/0x108
[  146.609192]  [<ffffffff811adcc4>] ? ext4_evict_inode+0x44/0x26f
[  146.609194]  [<ffffffff810852ef>] ? lock_release_nested+0x9f/0xa6
[  146.609197]  [<ffffffff814c5854>] _mutex_lock+0x31/0x40
[  146.609199]  [<ffffffff811adcc4>] ? ext4_evict_inode+0x44/0x26f
[  146.609201]  [<ffffffff814c91cd>] ? sub_preempt_count+0x4d/0x4f
[  146.609204]  [<ffffffff811adcc4>] ext4_evict_inode+0x44/0x26f
[  146.609206]  [<ffffffff811452b7>] evict+0x89/0x141
[  146.609208]  [<ffffffff81145501>] iput_final+0x14d/0x155
[  146.609210]  [<ffffffff81145543>] iput+0x3a/0x3e
[  146.609212]  [<ffffffff81140b61>] dentry_iput+0x97/0xaf
[  146.609214]  [<ffffffff81141e89>] dentry_kill+0xc7/0xde
[  146.609216]  [<ffffffff81142444>] dput+0xe3/0xf4
[  146.609218]  [<ffffffff8113157d>] __fput+0x1a9/0x1c1
[  146.609220]  [<ffffffff811315b2>] fput+0x1d/0x1f
[  146.609222]  [<ffffffff81107bb1>] remove_vma+0x3c/0x71
[  146.609224]  [<ffffffff81108d78>] do_munmap+0x267/0x280
[  146.609227]  [<ffffffff814c4f07>] ? rt_mutex_lock+0x15/0x17
[  146.609229]  [<ffffffff81108ef4>] sys_munmap+0x44/0x5b
[  146.609232]  [<ffffffff814cc2c2>] system_call_fastpath+0x16/0x1b


Config file attached.

Clark