Re: cx231xx: possible circular locking dependency detected on 3.2
Le Fri, 6 Jan 2012 22:42:31 +0100, Thomas Petazzoni thomas.petazz...@free-electrons.com a écrit : Hello, I'm running the Hauppauge USB-Live 2 device on an ARM OMAP3 platform. After loading the cx231xx driver and launching v4l2grab, I immediately get: [ 407.087158] cx231xx #0: setPowerMode::mode = 48, No Change req. [ 407.145477] [ 407.147064] == [ 407.153533] [ INFO: possible circular locking dependency detected ] [ 407.160095] 3.2.0-7-gb928298 #18 [ 407.163848] --- One code path is (mmap_sem taken before, video_device lock taken afterwards) : - sys_mmap_pgoff() grabs current-mm-mmap_sem at http://lxr.free-electrons.com/source/mm/mmap.c#L - do_mmap_pgoff() - mmap_region() - v4l2_mmap() grabs struct video_device-lock at http://lxr.free-electrons.com/source/drivers/media/video/v4l2-dev.c#L396 The other code path is (video_device taken first, mmap_sem taken afterwards) : - v4l2_ioctl() grabs video_device-lock at http://lxr.free-electrons.com/source/drivers/media/video/v4l2-dev.c#L327 - video_ioctl2() - video_usercopy() - __video_do_ioctl() - videobuf_qbuf() grabs current-mm-mmap_sem at http://lxr.free-electrons.com/source/drivers/media/video/videobuf-core.c#L537 Regards, Thomas -- Thomas Petazzoni, Free Electrons Kernel, drivers, real-time and embedded Linux development, consulting, training and support. http://free-electrons.com -- To unsubscribe from this list: send the line unsubscribe linux-media in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
cx231xx: possible circular locking dependency detected on 3.2
Hello,
I'm running the Hauppauge USB-Live 2 device on an ARM OMAP3 platform.
After loading the cx231xx driver and launching v4l2grab, I immediately
get:
[ 407.087158] cx231xx #0: setPowerMode::mode = 48, No Change req.
[ 407.145477]
[ 407.147064] ==
[ 407.153533] [ INFO: possible circular locking dependency detected ]
[ 407.160095] 3.2.0-7-gb928298 #18
[ 407.163848] ---
[ 407.170410] v4l2grab/680 is trying to acquire lock:
[ 407.175537] (mm-mmap_sem){++}, at: [bf03e10c]
videobuf_qbuf+0x298/0x48c [videobuf_core]
[ 407.184783]
[ 407.184783] but task is already holding lock:
[ 407.190887] (dev-lock#2){+.+.+.}, at: [bf00e47c] v4l2_ioctl+0xec/0x150
[videodev]
[ 407.199249]
[ 407.199249] which lock already depends on the new lock.
[ 407.199249]
[ 407.207824]
[ 407.207824] the existing dependency chain (in reverse order) is:
[ 407.215667]
[ 407.215667] - #1 (dev-lock#2){+.+.+.}:
[ 407.221435][c008bac8] lock_acquire+0x98/0x100
[ 407.226928][c0471594] mutex_lock_interruptible_nested+0x4c/0x37c
[ 407.234161][bf00e378] v4l2_mmap+0x94/0xac [videodev]
[ 407.240295][c00eee5c] mmap_region+0x2d4/0x468
[ 407.245788][c00ef3a0] sys_mmap_pgoff+0x78/0xc0
[ 407.251342][c0013b00] ret_fast_syscall+0x0/0x3c
[ 407.257019]
[ 407.257019] - #0 (mm-mmap_sem){++}:
[ 407.262878][c008b3f0] __lock_acquire+0x1d04/0x1d94
[ 407.268829][c008bac8] lock_acquire+0x98/0x100
[ 407.274291][c04726cc] down_read+0x2c/0x3c
[ 407.279418][bf03e10c] videobuf_qbuf+0x298/0x48c [videobuf_core]
[ 407.286529][bf00fbf4] __video_do_ioctl+0x500/0x55a8 [videodev]
[ 407.293579][bf00f2d0] video_usercopy+0x128/0x4d8 [videodev]
[ 407.300354][bf00e418] v4l2_ioctl+0x88/0x150 [videodev]
[ 407.306671][c0112cd4] do_vfs_ioctl+0x7c/0x584
[ 407.312164][c0113250] sys_ioctl+0x74/0x7c
[ 407.317260][c0013b00] ret_fast_syscall+0x0/0x3c
[ 407.322937]
[ 407.322937] other info that might help us debug this:
[ 407.322937]
[ 407.331329] Possible unsafe locking scenario:
[ 407.331329]
[ 407.337524]CPU0CPU1
[ 407.342285]
[ 407.347015] lock(dev-lock);
[ 407.350311]lock(mm-mmap_sem);
[ 407.356536]lock(dev-lock);
[ 407.362457] lock(mm-mmap_sem);
[ 407.366027]
[ 407.366027] *** DEADLOCK ***
[ 407.366027]
[ 407.372253] 1 lock held by v4l2grab/680:
[ 407.376342] #0: (dev-lock#2){+.+.+.}, at: [bf00e47c]
v4l2_ioctl+0xec/0x150 [videodev]
[ 407.385162]
[ 407.385162] stack backtrace:
[ 407.389739] [c001b3b0] (unwind_backtrace+0x0/0xf0) from [c0087c04]
(print_circular_bug+0x1d4/0x2f0)
[ 407.399597] [c0087c04] (print_circular_bug+0x1d4/0x2f0) from [c008b3f0]
(__lock_acquire+0x1d04/0x1d94)
[ 407.409729] [c008b3f0] (__lock_acquire+0x1d04/0x1d94) from [c008bac8]
(lock_acquire+0x98/0x100)
[ 407.419219] [c008bac8] (lock_acquire+0x98/0x100) from [c04726cc]
(down_read+0x2c/0x3c)
[ 407.427886] [c04726cc] (down_read+0x2c/0x3c) from [bf03e10c]
(videobuf_qbuf+0x298/0x48c [videobuf_core])
[ 407.438201] [bf03e10c] (videobuf_qbuf+0x298/0x48c [videobuf_core]) from
[bf00fbf4] (__video_do_ioctl+0x500/0x55a8 [videodev])
[ 407.450469] [bf00fbf4] (__video_do_ioctl+0x500/0x55a8 [videodev]) from
[bf00f2d0] (video_usercopy+0x128/0x4d8 [videodev])
[ 407.462341] [bf00f2d0] (video_usercopy+0x128/0x4d8 [videodev]) from
[bf00e418] (v4l2_ioctl+0x88/0x150 [videodev])
[ 407.473480] [bf00e418] (v4l2_ioctl+0x88/0x150 [videodev]) from
[c0112cd4] (do_vfs_ioctl+0x7c/0x584)
[ 407.483337] [c0112cd4] (do_vfs_ioctl+0x7c/0x584) from [c0113250]
(sys_ioctl+0x74/0x7c)
[ 407.492004] [c0113250] (sys_ioctl+0x74/0x7c) from [c0013b00]
(ret_fast_syscall+0x0/0x3c)
[ 407.500915] cx231xx #0: cx231xx_stop_stream():: ep_mask = 8
Best regards,
Thomas Petazzoni
--
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com
--
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