* Re: 4.6 regression: deadlock in exynos fimc_md_probe()
2016-05-01 16:43 ` 4.6 regression: deadlock in exynos fimc_md_probe() Hans Verkuil
@ 2016-05-01 22:04 ` Hans Verkuil
0 siblings, 0 replies; 2+ messages in thread
From: Hans Verkuil @ 2016-05-01 22:04 UTC (permalink / raw)
To: Mauro Carvalho Chehab
Cc: Marek Szyprowski, Sakari Ailus, Linux Media Mailing List
Oh never mind, Marek posted a patch for this on Thursday which I didn't notice.
Mauro, these two patches:
[PATCH 1/2] media: exynos4-is: fix deadlock on driver probe
[PATCH 2/2] media: s3c-camif: fix deadlock on driver probe()
should be fasttracked for 4.6.
Hans
On 05/01/2016 06:43 PM, Hans Verkuil wrote:
> On 05/01/2016 06:42 PM, Hans Verkuil wrote:
>> I'm adding Sakari since this problem was introduced in his commit 0c426c472b5585ed6e59160359c979506d45ae49:
>> "media: Always keep a graph walk large enough around".
>
> And now adding linux-media as well. Sorry about that.
>
> Hans
>
>>
>> Regards,
>>
>> Hans
>>
>> On 05/01/2016 06:15 PM, Hans Verkuil wrote:
>>> Hi Mauro,
>>>
>>> While testing an unrelated patch series for the exynos4 using kernel 4.6 I
>>> came across this deadlock that caused the boot sequence to hang (I'm using
>>> an exynos4 Odroid U3):
>>>
>>> =============================================
>>> [ INFO: possible recursive locking detected ]
>>> 4.6.0-rc5-odroid #987 Not tainted
>>> ---------------------------------------------
>>> swapper/0/1 is trying to acquire lock:
>>> (&mdev->graph_mutex){+.+.+.}, at: [<c05d96d4>] media_device_register_entity+0x78/0x1e8
>>>
>>> but task is already holding lock:
>>> (&mdev->graph_mutex){+.+.+.}, at: [<c060cec8>] fimc_md_probe+0x22c/0xac0
>>>
>>> other info that might help us debug this:
>>> Possible unsafe locking scenario:
>>>
>>> CPU0
>>> ----
>>> lock(&mdev->graph_mutex);
>>> lock(&mdev->graph_mutex);
>>>
>>> *** DEADLOCK ***
>>>
>>> May be due to missing lock nesting notation
>>>
>>> 4 locks held by swapper/0/1:
>>> #0: (&dev->mutex){......}, at: [<c04aed50>] __driver_attach+0x58/0xcc
>>> #1: (&dev->mutex){......}, at: [<c04aed60>] __driver_attach+0x68/0xcc
>>> #2: (&mdev->graph_mutex){+.+.+.}, at: [<c060cec8>] fimc_md_probe+0x22c/0xac0
>>> #3: (&dev->mutex){......}, at: [<c060cf98>] fimc_md_probe+0x2fc/0xac0
>>>
>>> stack backtrace:
>>> CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.6.0-rc5-odroid #987
>>> Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
>>> Backtrace:
>>> [<c010bd94>] (dump_backtrace) from [<c010bf90>] (show_stack+0x18/0x1c)
>>> r7:c0d1c9a4 r6:c0d1c9a4 r5:200001d3 r4:00000000
>>> [<c010bf78>] (show_stack) from [<c03e65dc>] (dump_stack+0xb0/0xdc)
>>> [<c03e652c>] (dump_stack) from [<c016c854>] (__lock_acquire+0x19bc/0x1dcc)
>>> r9:ee880000 r8:c1516a7c r7:c14dc9ec r6:c0e99058 r5:c0e99058 r4:c0e99058
>>> [<c016ae98>] (__lock_acquire) from [<c016d518>] (lock_acquire+0x78/0x98)
>>> r10:eefad144 r9:eea95044 r8:ee880000 r7:00000001 r6:00000000 r5:60000153
>>> r4:00000000
>>> [<c016d4a0>] (lock_acquire) from [<c089bd74>] (mutex_lock_nested+0x70/0x4c0)
>>> r7:c14dc9ec r6:c05d96d4 r5:00000000 r4:ee2bdcac
>>> [<c089bd04>] (mutex_lock_nested) from [<c05d96d4>] (media_device_register_entity+0x78/0x1e8)
>>> r10:eefad144 r9:eea95044 r8:ee2bdc44 r7:ee2bdcac r6:ee2bd910 r5:00000000
>>> r4:ee30d4d0
>>> [<c05d965c>] (media_device_register_entity) from [<c05e3ed8>] (v4l2_device_register_subdev+0xa4/0x174)
>>> r8:ee30d010 r7:eefad4ac r6:00000000 r5:ee2bdd90 r4:ee30d4d0
>>> [<c05e3e34>] (v4l2_device_register_subdev) from [<c060d1e0>] (fimc_md_probe+0x544/0xac0)
>>> r7:eefad4ac r6:eea95000 r5:ee30d4d0 r4:ee2bd810
>>> [<c060cc9c>] (fimc_md_probe) from [<c04b06bc>] (platform_drv_probe+0x54/0xb8)
>>> r10:00000116 r9:00000000 r8:c0d36da4 r7:fffffdfb r6:c0d36da4 r5:eea94c10
>>> r4:eea94c10
>>> [<c04b0668>] (platform_drv_probe) from [<c04aec4c>] (driver_probe_device+0x21c/0x2c8)
>>> r7:00000000 r6:c151c298 r5:c151c290 r4:eea94c10
>>> [<c04aea30>] (driver_probe_device) from [<c04aedc0>] (__driver_attach+0xc8/0xcc)
>>> r9:c0d52000 r8:00000000 r7:00000000 r6:eea94c44 r5:c0d36da4 r4:eea94c10
>>> [<c04aecf8>] (__driver_attach) from [<c04acd04>] (bus_for_each_dev+0x70/0xa4)
>>> r7:00000000 r6:c04aecf8 r5:c0d36da4 r4:00000000
>>> [<c04acc94>] (bus_for_each_dev) from [<c04ae43c>] (driver_attach+0x24/0x28)
>>> r6:c0d26af8 r5:eea76c80 r4:c0d36da4
>>> [<c04ae418>] (driver_attach) from [<c04adfd8>] (bus_add_driver+0x1a8/0x220)
>>> [<c04ade30>] (bus_add_driver) from [<c04af560>] (driver_register+0x80/0x100)
>>> r7:edd74d80 r6:c0d05a90 r5:c0c1c83c r4:c0d36da4
>>> [<c04af4e0>] (driver_register) from [<c04b061c>] (__platform_driver_register+0x48/0x50)
>>> r5:c0c1c83c r4:c0d05a90
>>> [<c04b05d4>] (__platform_driver_register) from [<c0c1c870>] (fimc_md_init+0x34/0x40)
>>> [<c0c1c83c>] (fimc_md_init) from [<c0101898>] (do_one_initcall+0x98/0x1e4)
>>> [<c0101800>] (do_one_initcall) from [<c0c00e34>] (kernel_init_freeable+0x164/0x208)
>>> r8:00000006 r7:c0c34858 r6:c0c00608 r5:c0c34850 r4:c0d52000
>>> [<c0c00cd0>] (kernel_init_freeable) from [<c0899c84>] (kernel_init+0x10/0x11c)
>>> r10:00000000 r9:00000000 r8:00000000 r7:00000000 r6:00000000 r5:c0899c74
>>> r4:00000000
>>> [<c0899c74>] (kernel_init) from [<c0107cf0>] (ret_from_fork+0x14/0x24)
>>> r5:c0899c74 r4:00000000
>>>
>>> Commenting out 'mutex_lock(&fmd->media_dev.graph_mutex);' in fimc_md_probe()
>>> makes it boot again, but I'm not 100% certain that's correct.
>>>
>>> Can you take a look?
>>>
>>> Thanks!
>>>
>>> Hans
>>>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-media" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
>
^ permalink raw reply [flat|nested] 2+ messages in thread