Re: Odroid U3 mutex deadlock.

[Marek Szyprowski]

Hi Anand,

On 2016-01-02 06:14, Anand Moon wrote:

Hi Krzysztof

On 14 December 2015 at 05:15, Krzysztof Kozlowski
 wrote:

On 12.12.2015 13:32, Anand Moon wrote:

Hi Krzysztof,

I am just observing this deadlock om my Odroid U3.

This is not a deadlock yet, just a report from lockdep. Could be a real
issue, could be false positive, maybe some locks miss nesting annotations.

Typical information for bug report would be useful, like the exact
version (it is mentioned in lockdep report but is it really correct?)
and reproducibility. And of course git-bisect would be nice to have, see:
Documentation/BUG-HUNTING

Best regards,
Krzysztof



Thanks for your inputs. I narrowed down to this commit.
--
commit ec459c0c77faca53cf161830cb264e51bb1abba6
Author: Marek Szyprowski 
Date:   Wed Feb 4 23:44:15 2015 +0900

 ARM: dts: add dependency between TV and LCD0 power domains for exynos4

 TV Mixer needs both TV and LCD0 domains enabled to be fully operational.
 This dependency is modelled by making TV power domains a sub-domain of
 LCD0 power domain.

 Signed-off-by: Marek Szyprowski 
 Signed-off-by: Kukjin Kim 
-
After reverting this I am not observing below lockdep warning report.
But after reverting this patch I observer another bug.


The mentioned lockdep warning is a false positive. Such warning is 
reported for

every subdomain present in a system. As you noticed that removing dependency
between power domains also removes this warning, but it will introduce real
problems with power on/off sequences of graphics devices.

I will send a patch for genpd core fixing the deplock warning. Thanks for
reporting the issue and pointing a good place to start digging in the 
source :)


Best regards
--
Marek Szyprowski, PhD
Samsung R Institute Poland

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Re: Odroid U3 mutex deadlock.

[Anand Moon]

Hi Krzysztof

On 14 December 2015 at 05:15, Krzysztof Kozlowski
 wrote:
> On 12.12.2015 13:32, Anand Moon wrote:
>> Hi Krzysztof,
>>
>> I am just observing this deadlock om my Odroid U3.
>
> This is not a deadlock yet, just a report from lockdep. Could be a real
> issue, could be false positive, maybe some locks miss nesting annotations.
>
> Typical information for bug report would be useful, like the exact
> version (it is mentioned in lockdep report but is it really correct?)
> and reproducibility. And of course git-bisect would be nice to have, see:
> Documentation/BUG-HUNTING
>
> Best regards,
> Krzysztof
>
>
Thanks for your inputs. I narrowed down to this commit.
--
commit ec459c0c77faca53cf161830cb264e51bb1abba6
Author: Marek Szyprowski 
Date:   Wed Feb 4 23:44:15 2015 +0900

ARM: dts: add dependency between TV and LCD0 power domains for exynos4

TV Mixer needs both TV and LCD0 domains enabled to be fully operational.
This dependency is modelled by making TV power domains a sub-domain of
LCD0 power domain.

Signed-off-by: Marek Szyprowski 
Signed-off-by: Kukjin Kim 
-
After reverting this I am not observing below lockdep warning report.
But after reverting this patch I observer another bug.

Best regards.
-Anand Moon

>> --
>>
>> [2.937531] =
>> [2.938733] [ INFO: possible recursive locking detected ]
>> [2.944117] 4.4.0-rc4-xu3s #32 Not tainted
>> [2.948195] -
>> [2.953577] swapper/0/1 is trying to acquire lock:
>> [2.958351]  (>lock){+.+...}, at: []
>> __genpd_poweron+0x64/0x108
>> [2.965727]
>> [2.965727] but task is already holding lock:
>> [2.971543]  (>lock){+.+...}, at: []
>> genpd_dev_pm_attach+0x168/0x1b8
>> [2.979355]
>> [2.979355] other info that might help us debug this:
>> [2.985865]  Possible unsafe locking scenario:
>> [2.985865]
>> [2.991768]CPU0
>> [2.994198]
>> [2.996628]   lock(>lock);
>> [2.26]   lock(>lock);
>> [3.003225]
>> [3.003225]  *** DEADLOCK ***
>> [3.003225]
>> [3.009128]  May be due to missing lock nesting notation
>> [3.009128]
>> [3.015900] 3 locks held by swapper/0/1:
>> [3.019804]  #0:  (>mutex){..}, at: []
>> __driver_attach+0x48/0x98
>> [3.027442]  #1:  (>mutex){..}, at: []
>> __driver_attach+0x58/0x98
>> [3.035081]  #2:  (>lock){+.+...}, at: []
>> genpd_dev_pm_attach+0x168/0x1b8
>> [3.043326]
>> [3.043326] stack backtrace:
>> [3.047671] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.4.0-rc4-xu3s #32
>> [3.054351] Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
>> [3.060444] [] (unwind_backtrace) from []
>> (show_stack+0x10/0x14)
>> [3.068163] [] (show_stack) from []
>> (dump_stack+0x84/0xc4)
>> [3.075367] [] (dump_stack) from []
>> (__lock_acquire+0x1f88/0x215c)
>> [3.083262] [] (__lock_acquire) from []
>> (lock_acquire+0xa4/0xd0)
>> [3.090990] [] (lock_acquire) from []
>> (mutex_lock_nested+0x70/0x4d4)
>> [3.099061] [] (mutex_lock_nested) from []
>> (__genpd_poweron+0x64/0x108)
>> [3.107393] [] (__genpd_poweron) from []
>> (genpd_dev_pm_attach+0x170/0x1b8)
>> [3.115986] [] (genpd_dev_pm_attach) from []
>> (platform_drv_probe+0x2c/0xac)
>> [3.124667] [] (platform_drv_probe) from []
>> (driver_probe_device+0x208/0x2fc)
>> [3.133519] [] (driver_probe_device) from []
>> (__driver_attach+0x94/0x98)
>> [3.141939] [] (__driver_attach) from []
>> (bus_for_each_dev+0x68/0x9c)
>> [3.150097] [] (bus_for_each_dev) from []
>> (bus_add_driver+0x1a0/0x218)
>> [3.158344] [] (bus_add_driver) from []
>> (driver_register+0x78/0xf8)
>> [3.166330] [] (driver_register) from []
>> (exynos_drm_register_drivers+0x28/0x74)
>> [3.175441] [] (exynos_drm_register_drivers) from
>> [] (exynos_drm_init+0x6c/0xc4)
>> [3.184556] [] (exynos_drm_init) from []
>> (do_one_initcall+0x90/0x1dc)
>> [3.192718] [] (do_one_initcall) from []
>> (kernel_init_freeable+0x158/0x1f8)
>> [3.201396] [] (kernel_init_freeable) from []
>> (kernel_init+0x8/0xe8)
>> [3.209469] [] (kernel_init) from []
>> (ret_from_fork+0x14/0x24)
>> [3.217932] exynos-hdmi 12d0.hdmi: GPIO lookup for consumer hpd
>> [3.223293] exynos-hdmi 12d0.hdmi: using device tree for GPIO lookup
>> [3.229980] of_get_named_gpiod_flags: can't parse 'hpd-gpios'
>> property of node '/hdmi@12D0[0]'
>> [3.238945] of_get_named_gpiod_flags: parsed 'hpd-gpio' property of
>> node '/hdmi@12D0[0]' - status (0)
>> [3.253430] 

Re: Odroid U3 mutex deadlock.

[Krzysztof Kozlowski]

On 12.12.2015 13:32, Anand Moon wrote:
> Hi Krzysztof,
> 
> I am just observing this deadlock om my Odroid U3.

This is not a deadlock yet, just a report from lockdep. Could be a real
issue, could be false positive, maybe some locks miss nesting annotations.

Typical information for bug report would be useful, like the exact
version (it is mentioned in lockdep report but is it really correct?)
and reproducibility. And of course git-bisect would be nice to have, see:
Documentation/BUG-HUNTING

Best regards,
Krzysztof


> --
> 
> [2.937531] =
> [2.938733] [ INFO: possible recursive locking detected ]
> [2.944117] 4.4.0-rc4-xu3s #32 Not tainted
> [2.948195] -
> [2.953577] swapper/0/1 is trying to acquire lock:
> [2.958351]  (>lock){+.+...}, at: []
> __genpd_poweron+0x64/0x108
> [2.965727]
> [2.965727] but task is already holding lock:
> [2.971543]  (>lock){+.+...}, at: []
> genpd_dev_pm_attach+0x168/0x1b8
> [2.979355]
> [2.979355] other info that might help us debug this:
> [2.985865]  Possible unsafe locking scenario:
> [2.985865]
> [2.991768]CPU0
> [2.994198]
> [2.996628]   lock(>lock);
> [2.26]   lock(>lock);
> [3.003225]
> [3.003225]  *** DEADLOCK ***
> [3.003225]
> [3.009128]  May be due to missing lock nesting notation
> [3.009128]
> [3.015900] 3 locks held by swapper/0/1:
> [3.019804]  #0:  (>mutex){..}, at: []
> __driver_attach+0x48/0x98
> [3.027442]  #1:  (>mutex){..}, at: []
> __driver_attach+0x58/0x98
> [3.035081]  #2:  (>lock){+.+...}, at: []
> genpd_dev_pm_attach+0x168/0x1b8
> [3.043326]
> [3.043326] stack backtrace:
> [3.047671] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.4.0-rc4-xu3s #32
> [3.054351] Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
> [3.060444] [] (unwind_backtrace) from []
> (show_stack+0x10/0x14)
> [3.068163] [] (show_stack) from []
> (dump_stack+0x84/0xc4)
> [3.075367] [] (dump_stack) from []
> (__lock_acquire+0x1f88/0x215c)
> [3.083262] [] (__lock_acquire) from []
> (lock_acquire+0xa4/0xd0)
> [3.090990] [] (lock_acquire) from []
> (mutex_lock_nested+0x70/0x4d4)
> [3.099061] [] (mutex_lock_nested) from []
> (__genpd_poweron+0x64/0x108)
> [3.107393] [] (__genpd_poweron) from []
> (genpd_dev_pm_attach+0x170/0x1b8)
> [3.115986] [] (genpd_dev_pm_attach) from []
> (platform_drv_probe+0x2c/0xac)
> [3.124667] [] (platform_drv_probe) from []
> (driver_probe_device+0x208/0x2fc)
> [3.133519] [] (driver_probe_device) from []
> (__driver_attach+0x94/0x98)
> [3.141939] [] (__driver_attach) from []
> (bus_for_each_dev+0x68/0x9c)
> [3.150097] [] (bus_for_each_dev) from []
> (bus_add_driver+0x1a0/0x218)
> [3.158344] [] (bus_add_driver) from []
> (driver_register+0x78/0xf8)
> [3.166330] [] (driver_register) from []
> (exynos_drm_register_drivers+0x28/0x74)
> [3.175441] [] (exynos_drm_register_drivers) from
> [] (exynos_drm_init+0x6c/0xc4)
> [3.184556] [] (exynos_drm_init) from []
> (do_one_initcall+0x90/0x1dc)
> [3.192718] [] (do_one_initcall) from []
> (kernel_init_freeable+0x158/0x1f8)
> [3.201396] [] (kernel_init_freeable) from []
> (kernel_init+0x8/0xe8)
> [3.209469] [] (kernel_init) from []
> (ret_from_fork+0x14/0x24)
> [3.217932] exynos-hdmi 12d0.hdmi: GPIO lookup for consumer hpd
> [3.223293] exynos-hdmi 12d0.hdmi: using device tree for GPIO lookup
> [3.229980] of_get_named_gpiod_flags: can't parse 'hpd-gpios'
> property of node '/hdmi@12D0[0]'
> [3.238945] of_get_named_gpiod_flags: parsed 'hpd-gpio' property of
> node '/hdmi@12D0[0]' - status (0)
> [3.253430] exynos-drm exynos-drm: bound 12c1.mixer (ops
> mixer_component_ops)
> [3.256216] exynos-drm exynos-drm: bound 12d0.hdmi (ops
> hdmi_component_ops)
> [3.263245] [drm] Supports vblank timestamp caching Rev 2 (21.10.2013).
> [3.269812] [drm] No driver support for vblank timestamp query.
> [3.323251] exynos-drm exynos-drm: fb0:  frame buffer device
> [3.341464] [drm] Initialized exynos 1.0.0 20110530 on minor 0
> 
> ---
> -Anand Moon
> 
> 

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Re: Odroid U3 mutex deadlock.

[Anand Moon]

Hi Thomas,

On 12 December 2015 at 16:58, Thomas Pietrowski  wrote:
> I'm also using 4.4.0-rc4 here on my U3+. And so far it is working well. I
> just had a freeze yesterday, but I didn't had the UART connected, so
> couldn't catch the reason. The curious thing was that the heartbeat LED was
> still blinking, but USB keyboard and Ethernet/SSH (but LEDs still on) were
> not working.
>
> Could you upload your .config? Maybe it could be useful for others :)
>
> Regards
>
> Am 12.12.2015 05:33 schrieb "Anand Moon" :
>>
>> Hi Krzysztof,
>>
>> I am just observing this deadlock om my Odroid U3.
>>
>> --
>>
>> [2.937531] =
>> [2.938733] [ INFO: possible recursive locking detected ]
>> [2.944117] 4.4.0-rc4-xu3s #32 Not tainted
>> [2.948195] -
>> [2.953577] swapper/0/1 is trying to acquire lock:
>> [2.958351]  (>lock){+.+...}, at: []
>> __genpd_poweron+0x64/0x108
>> [2.965727]
>> [2.965727] but task is already holding lock:
>> [2.971543]  (>lock){+.+...}, at: []
>> genpd_dev_pm_attach+0x168/0x1b8
>> [2.979355]
>> [2.979355] other info that might help us debug this:
>> [2.985865]  Possible unsafe locking scenario:
>> [2.985865]
>> [2.991768]CPU0
>> [2.994198]
>> [2.996628]   lock(>lock);
>> [2.26]   lock(>lock);
>> [3.003225]
>> [3.003225]  *** DEADLOCK ***
>> [3.003225]
>> [3.009128]  May be due to missing lock nesting notation
>> [3.009128]
>> [3.015900] 3 locks held by swapper/0/1:
>> [3.019804]  #0:  (>mutex){..}, at: []
>> __driver_attach+0x48/0x98
>> [3.027442]  #1:  (>mutex){..}, at: []
>> __driver_attach+0x58/0x98
>> [3.035081]  #2:  (>lock){+.+...}, at: []
>> genpd_dev_pm_attach+0x168/0x1b8
>> [3.043326]
>> [3.043326] stack backtrace:
>> [3.047671] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.4.0-rc4-xu3s
>> #32
>> [3.054351] Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
>> [3.060444] [] (unwind_backtrace) from []
>> (show_stack+0x10/0x14)
>> [3.068163] [] (show_stack) from []
>> (dump_stack+0x84/0xc4)
>> [3.075367] [] (dump_stack) from []
>> (__lock_acquire+0x1f88/0x215c)
>> [3.083262] [] (__lock_acquire) from []
>> (lock_acquire+0xa4/0xd0)
>> [3.090990] [] (lock_acquire) from []
>> (mutex_lock_nested+0x70/0x4d4)
>> [3.099061] [] (mutex_lock_nested) from []
>> (__genpd_poweron+0x64/0x108)
>> [3.107393] [] (__genpd_poweron) from []
>> (genpd_dev_pm_attach+0x170/0x1b8)
>> [3.115986] [] (genpd_dev_pm_attach) from []
>> (platform_drv_probe+0x2c/0xac)
>> [3.124667] [] (platform_drv_probe) from []
>> (driver_probe_device+0x208/0x2fc)
>> [3.133519] [] (driver_probe_device) from []
>> (__driver_attach+0x94/0x98)
>> [3.141939] [] (__driver_attach) from []
>> (bus_for_each_dev+0x68/0x9c)
>> [3.150097] [] (bus_for_each_dev) from []
>> (bus_add_driver+0x1a0/0x218)
>> [3.158344] [] (bus_add_driver) from []
>> (driver_register+0x78/0xf8)
>> [3.166330] [] (driver_register) from []
>> (exynos_drm_register_drivers+0x28/0x74)
>> [3.175441] [] (exynos_drm_register_drivers) from
>> [] (exynos_drm_init+0x6c/0xc4)
>> [3.184556] [] (exynos_drm_init) from []
>> (do_one_initcall+0x90/0x1dc)
>> [3.192718] [] (do_one_initcall) from []
>> (kernel_init_freeable+0x158/0x1f8)
>> [3.201396] [] (kernel_init_freeable) from []
>> (kernel_init+0x8/0xe8)
>> [3.209469] [] (kernel_init) from []
>> (ret_from_fork+0x14/0x24)
>> [3.217932] exynos-hdmi 12d0.hdmi: GPIO lookup for consumer hpd
>> [3.223293] exynos-hdmi 12d0.hdmi: using device tree for GPIO
>> lookup
>> [3.229980] of_get_named_gpiod_flags: can't parse 'hpd-gpios'
>> property of node '/hdmi@12D0[0]'
>> [3.238945] of_get_named_gpiod_flags: parsed 'hpd-gpio' property of
>> node '/hdmi@12D0[0]' - status (0)
>> [3.253430] exynos-drm exynos-drm: bound 12c1.mixer (ops
>> mixer_component_ops)
>> [3.256216] exynos-drm exynos-drm: bound 12d0.hdmi (ops
>> hdmi_component_ops)
>> [3.263245] [drm] Supports vblank timestamp caching Rev 2 (21.10.2013).
>> [3.269812] [drm] No driver support for vblank timestamp query.
>> [3.323251] exynos-drm exynos-drm: fb0:  frame buffer device
>> [3.341464] [drm] Initialized exynos 1.0.0 20110530 on minor 0
>>
>>
>> ---
>> -Anand Moon

I just using exynos_defconfig + kernel hacking flags.

diff --git a/arch/arm/configs/exynos_defconfig
b/arch/arm/configs/exynos_defconfig
index e0841a5..402a37f 100644
--- a/arch/arm/configs/exynos_defconfig
+++ b/arch/arm/configs/exynos_defconfig
@@ -1,3 +1,4 @@
+#