linux-kernel - Re: 2.6.29-rc1: i915 lockdep warning

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Date:	Fri, 30 Jan 2009 14:42:16 -0500
From:	Bob Copeland <me@...copeland.com>
To:	"Brandeburg, Jesse" <jesse.brandeburg@...el.com>
Cc:	Linux kernel mailing list <linux-kernel@...r.kernel.org>,
	"airlied@...ux.ie" <airlied@...ux.ie>,
	"dri-devel@...ts.sourceforge.net" <dri-devel@...ts.sourceforge.net>,
	"keithp@...thp.com" <keithp@...thp.com>,
	Ingo Molnar <mingo@...e.hu>,
	"arjan@...ux.intel.com" <arjan@...ux.intel.com>
Subject: Re: 2.6.29-rc1: i915 lockdep warning

On Tue, Jan 13, 2009 at 6:17 PM, Brandeburg, Jesse
<jesse.brandeburg@...el.com> wrote:
> [drm] Initialized i915 1.6.0 20080730 on minor 0
>
> =======================================================
> [ INFO: possible circular locking dependency detected ]
> 2.6.29-rc1 #1
> -------------------------------------------------------

Same here, this happens every time I start X, still in -rc3.  I can test
any patches.  This is Fedora 10.

=======================================================
[ INFO: possible circular locking dependency detected ]
2.6.29-rc3 #45
-------------------------------------------------------
Xorg/3108 is trying to acquire lock:
 (&mm->mmap_sem){----}, at: [<c016a148>] might_fault+0x48/0x84

but task is already holding lock:
 (&dev->struct_mutex){--..}, at: [<f82ded8c>]
i915_gem_execbuffer+0x124/0xa48 [i915]

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&dev->struct_mutex){--..}:
       [<c0140197>] __lock_acquire+0xfb9/0x12d3
       [<f82bdd47>] drm_vm_open+0x22/0x32 [drm]
       [<f82bdd47>] drm_vm_open+0x22/0x32 [drm]
       [<c01404fa>] lock_acquire+0x49/0x61
       [<f82bdd47>] drm_vm_open+0x22/0x32 [drm]
       [<c031300b>] mutex_lock_nested+0xe6/0x27d
       [<f82bdd47>] drm_vm_open+0x22/0x32 [drm]
       [<f82bdd47>] drm_vm_open+0x22/0x32 [drm]
       [<f82bdd47>] drm_vm_open+0x22/0x32 [drm]
       [<c012117c>] dup_mm+0x26d/0x31c
       [<c0121bd1>] copy_process+0x983/0xfaf
       [<c012b314>] do_sigaction+0x6a/0x13d
       [<c0122315>] do_fork+0x118/0x2a6
       [<c012b489>] sys_rt_sigaction+0x66/0x79
       [<c0102e77>] sysenter_exit+0xf/0x18
       [<c010165a>] sys_clone+0x22/0x26
       [<c0102e45>] sysenter_do_call+0x12/0x35
       [<ffffffff>] 0xffffffff

-> #1 (&mm->mmap_sem/1){--..}:
       [<c0140197>] __lock_acquire+0xfb9/0x12d3
       [<c0120fba>] dup_mm+0xab/0x31c
       [<c0120fba>] dup_mm+0xab/0x31c
       [<c01404fa>] lock_acquire+0x49/0x61
       [<c0120fba>] dup_mm+0xab/0x31c
       [<c0135605>] down_write_nested+0x2b/0x45
       [<c0120fba>] dup_mm+0xab/0x31c
       [<c0120fba>] dup_mm+0xab/0x31c
       [<c0121b2c>] copy_process+0x8de/0xfaf
       [<c0121bd1>] copy_process+0x983/0xfaf
       [<c0122315>] do_fork+0x118/0x2a6
       [<c01f4eaf>] copy_to_user+0x29/0xf8
       [<c0102e77>] sysenter_exit+0xf/0x18
       [<c010165a>] sys_clone+0x22/0x26
       [<c0102e45>] sysenter_do_call+0x12/0x35
       [<ffffffff>] 0xffffffff

-> #0 (&mm->mmap_sem){----}:
       [<c013fec7>] __lock_acquire+0xce9/0x12d3
       [<c0314559>] _spin_unlock+0x25/0x3a
       [<c01404fa>] lock_acquire+0x49/0x61
       [<c016a148>] might_fault+0x48/0x84
       [<c016a165>] might_fault+0x65/0x84
       [<c016a148>] might_fault+0x48/0x84
       [<c01f4eaf>] copy_to_user+0x29/0xf8
       [<f82df5ec>] i915_gem_execbuffer+0x984/0xa48 [i915]
       [<c016a148>] might_fault+0x48/0x84
       [<f82b951a>] drm_ioctl+0x1a9/0x221 [drm]
       [<f82dec68>] i915_gem_execbuffer+0x0/0xa48 [i915]
       [<c0186102>] vfs_ioctl+0x49/0x5f
       [<c0186656>] do_vfs_ioctl+0x46c/0x4a7
       [<c03144c8>] _spin_unlock_irq+0x2b/0x40
       [<c0125cd9>] do_setitimer+0x15d/0x2af
       [<c0125e70>] sys_setitimer+0x45/0x6f
       [<c01866bd>] sys_ioctl+0x2c/0x42
       [<c0102e45>] sysenter_do_call+0x12/0x35
       [<ffffffff>] 0xffffffff

other info that might help us debug this:

1 lock held by Xorg/3108:
 #0:  (&dev->struct_mutex){--..}, at: [<f82ded8c>]
i915_gem_execbuffer+0x124/0xa48 [i915]

stack backtrace:
Pid: 3108, comm: Xorg Not tainted 2.6.29-rc3 #45
Call Trace:
 [<c013eeb5>] print_circular_bug_tail+0xa4/0xae
 [<c013fec7>] __lock_acquire+0xce9/0x12d3
 [<c0314559>] _spin_unlock+0x25/0x3a
 [<c01404fa>] lock_acquire+0x49/0x61
 [<c016a148>] might_fault+0x48/0x84
 [<c016a165>] might_fault+0x65/0x84
 [<c016a148>] might_fault+0x48/0x84
 [<c01f4eaf>] copy_to_user+0x29/0xf8
 [<f82df5ec>] i915_gem_execbuffer+0x984/0xa48 [i915]
 [<c016a148>] might_fault+0x48/0x84
 [<f82b951a>] drm_ioctl+0x1a9/0x221 [drm]
 [<f82dec68>] i915_gem_execbuffer+0x0/0xa48 [i915]
 [<c0186102>] vfs_ioctl+0x49/0x5f
 [<c0186656>] do_vfs_ioctl+0x46c/0x4a7
 [<c03144c8>] _spin_unlock_irq+0x2b/0x40
 [<c0125cd9>] do_setitimer+0x15d/0x2af
 [<c0125e70>] sys_setitimer+0x45/0x6f
 [<c01866bd>] sys_ioctl+0x2c/0x42
 [<c0102e45>] sysenter_do_call+0x12/0x35

-- 
Bob Copeland %% www.bobcopeland.com
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