From: Rui Wang <[email protected]>
There are still some places in the fb helper that need to avoid
sleeping in panic context. Here's an example:
[ 65.615496] bad: scheduling from the idle thread!
[ 65.620747] CPU: 92 PID: 0 Comm: swapper/92 Tainted: G M E 3.18.0-rc4-7-default+ #20
[ 65.630364] Hardware name: Intel Corporation BRICKLAND/BRICKLAND, BIOS BRHSXSD1.86B.0056.R01.1409242327 09/24/2014
[ 65.641923] ffff88087f693d80 ffff88087f689878 ffffffff81566db9 0000000000000000
[ 65.650226] ffff88087f693d80 ffff88087f689898 ffffffff810871ff ffff88046eb3e0d0
[ 65.658527] ffff88087f693d80 ffff88087f6898c8 ffffffff8107c1fa 000000017f6898b8
[ 65.666830] Call Trace:
[ 65.669557] <#MC> [<ffffffff81566db9>] dump_stack+0x46/0x58
[ 65.675994] [<ffffffff810871ff>] dequeue_task_idle+0x2f/0x40
[ 65.682412] [<ffffffff8107c1fa>] dequeue_task+0x5a/0x80
[ 65.688345] [<ffffffff810804f3>] deactivate_task+0x23/0x30
[ 65.694569] [<ffffffff81569050>] __schedule+0x580/0x7f0
[ 65.700502] [<ffffffff81569739>] schedule_preempt_disabled+0x29/0x70
[ 65.707696] [<ffffffff8156abb6>] __ww_mutex_lock_slowpath+0xb8/0x162
[ 65.714891] [<ffffffff8156acb3>] __ww_mutex_lock+0x53/0x85
[ 65.721125] [<ffffffffa00b3a5d>] drm_modeset_lock+0x3d/0x110 [drm]
[ 65.728132] [<ffffffffa00b3c2a>] __drm_modeset_lock_all+0x8a/0x120 [drm]
[ 65.735721] [<ffffffffa00b3cd0>] drm_modeset_lock_all+0x10/0x30 [drm]
[ 65.743015] [<ffffffffa01af8bf>] drm_fb_helper_pan_display+0x2f/0xf0 [drm_kms_helper]
[ 65.751857] [<ffffffff8132bd21>] fb_pan_display+0xd1/0x1a0
[ 65.758081] [<ffffffff81326010>] bit_update_start+0x20/0x50
[ 65.764400] [<ffffffff813259f2>] fbcon_switch+0x3a2/0x550
[ 65.770528] [<ffffffff813a01c9>] redraw_screen+0x189/0x240
[ 65.776750] [<ffffffff81322f8a>] fbcon_blank+0x20a/0x2d0
[ 65.782778] [<ffffffff8137d359>] ? erst_writer+0x209/0x330
[ 65.789002] [<ffffffff810ba2f3>] ? internal_add_timer+0x63/0x80
[ 65.795710] [<ffffffff810bc137>] ? mod_timer+0x127/0x1e0
[ 65.801740] [<ffffffff813a0cd8>] do_unblank_screen+0xa8/0x1d0
[ 65.808255] [<ffffffff813a0e10>] unblank_screen+0x10/0x20
[ 65.814381] [<ffffffff812ca0d9>] bust_spinlocks+0x19/0x40
[ 65.820508] [<ffffffff81561ca7>] panic+0x106/0x1f5
[ 65.825955] [<ffffffff8102336c>] mce_panic+0x2ac/0x2e0
[ 65.831789] [<ffffffff812c796a>] ? delay_tsc+0x4a/0x80
[ 65.837625] [<ffffffff81024e1f>] do_machine_check+0xbaf/0xbf0
[ 65.844138] [<ffffffff813365d7>] ? intel_idle+0xc7/0x150
[ 65.850166] [<ffffffff8156f03f>] machine_check+0x1f/0x30
[ 65.856195] [<ffffffff813365d7>] ? intel_idle+0xc7/0x150
[ 65.862222] <<EOE>> [<ffffffff814283d5>] cpuidle_enter_state+0x55/0x170
[ 65.869823] [<ffffffff814285a7>] cpuidle_enter+0x17/0x20
[ 65.875852] [<ffffffff81097b08>] cpu_startup_entry+0x2d8/0x370
[ 65.882467] [<ffffffff8102fe29>] start_secondary+0x159/0x180
There's __drm_modeset_lock_all() which Daniel Vetter introduced for this
purpose. We can leverage that without reinventing anything. This patch
works with the latest kernel.
Signed-off-by: Rui Wang <[email protected]>
---
drivers/gpu/drm/drm_fb_helper.c | 8 ++++++--
1 files changed, 6 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index 0c0c39b..70dd2f4 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -732,7 +732,9 @@ int drm_fb_helper_setcmap(struct fb_cmap *cmap, struct fb_info *info)
int i, j, rc = 0;
int start;
- drm_modeset_lock_all(dev);
+ if (__drm_modeset_lock_all(dev, !!oops_in_progress)) {
+ return -EBUSY;
+ }
if (!drm_fb_helper_is_bound(fb_helper)) {
drm_modeset_unlock_all(dev);
return -EBUSY;
@@ -910,7 +912,9 @@ int drm_fb_helper_pan_display(struct fb_var_screeninfo *var,
int ret = 0;
int i;
- drm_modeset_lock_all(dev);
+ if (__drm_modeset_lock_all(dev, !!oops_in_progress)) {
+ return -EBUSY;
+ }
if (!drm_fb_helper_is_bound(fb_helper)) {
drm_modeset_unlock_all(dev);
return -EBUSY;
--
1.7.5.4
BTW, the impact of this bug is that the panic cannot reboot the
machine and it prints an infinite stream of the error messages. The
panic goes on forever because there's a for(;;) loop in
__mutex_lock_common(), so we enter __schedule() again and again.
Thanks
Rui
On 12/4/14, [email protected] <[email protected]> wrote:
> From: Rui Wang <[email protected]>
>
> There are still some places in the fb helper that need to avoid
> sleeping in panic context. Here's an example:
>
> [ 65.615496] bad: scheduling from the idle thread!
> [ 65.620747] CPU: 92 PID: 0 Comm: swapper/92 Tainted: G M E
> 3.18.0-rc4-7-default+ #20
>
> [ 65.630364] Hardware name: Intel Corporation BRICKLAND/BRICKLAND, BIOS
> BRHSXSD1.86B.0056.R01.1409242327 09/24/2014
> [ 65.641923] ffff88087f693d80 ffff88087f689878 ffffffff81566db9
> 0000000000000000
> [ 65.650226] ffff88087f693d80 ffff88087f689898 ffffffff810871ff
> ffff88046eb3e0d0
> [ 65.658527] ffff88087f693d80 ffff88087f6898c8 ffffffff8107c1fa
> 000000017f6898b8
> [ 65.666830] Call Trace:
> [ 65.669557] <#MC> [<ffffffff81566db9>] dump_stack+0x46/0x58
> [ 65.675994] [<ffffffff810871ff>] dequeue_task_idle+0x2f/0x40
> [ 65.682412] [<ffffffff8107c1fa>] dequeue_task+0x5a/0x80
> [ 65.688345] [<ffffffff810804f3>] deactivate_task+0x23/0x30
> [ 65.694569] [<ffffffff81569050>] __schedule+0x580/0x7f0
> [ 65.700502] [<ffffffff81569739>] schedule_preempt_disabled+0x29/0x70
> [ 65.707696] [<ffffffff8156abb6>] __ww_mutex_lock_slowpath+0xb8/0x162
> [ 65.714891] [<ffffffff8156acb3>] __ww_mutex_lock+0x53/0x85
> [ 65.721125] [<ffffffffa00b3a5d>] drm_modeset_lock+0x3d/0x110 [drm]
> [ 65.728132] [<ffffffffa00b3c2a>] __drm_modeset_lock_all+0x8a/0x120
> [drm]
> [ 65.735721] [<ffffffffa00b3cd0>] drm_modeset_lock_all+0x10/0x30 [drm]
> [ 65.743015] [<ffffffffa01af8bf>] drm_fb_helper_pan_display+0x2f/0xf0
> [drm_kms_helper]
> [ 65.751857] [<ffffffff8132bd21>] fb_pan_display+0xd1/0x1a0
> [ 65.758081] [<ffffffff81326010>] bit_update_start+0x20/0x50
> [ 65.764400] [<ffffffff813259f2>] fbcon_switch+0x3a2/0x550
> [ 65.770528] [<ffffffff813a01c9>] redraw_screen+0x189/0x240
> [ 65.776750] [<ffffffff81322f8a>] fbcon_blank+0x20a/0x2d0
> [ 65.782778] [<ffffffff8137d359>] ? erst_writer+0x209/0x330
> [ 65.789002] [<ffffffff810ba2f3>] ? internal_add_timer+0x63/0x80
> [ 65.795710] [<ffffffff810bc137>] ? mod_timer+0x127/0x1e0
> [ 65.801740] [<ffffffff813a0cd8>] do_unblank_screen+0xa8/0x1d0
> [ 65.808255] [<ffffffff813a0e10>] unblank_screen+0x10/0x20
> [ 65.814381] [<ffffffff812ca0d9>] bust_spinlocks+0x19/0x40
> [ 65.820508] [<ffffffff81561ca7>] panic+0x106/0x1f5
> [ 65.825955] [<ffffffff8102336c>] mce_panic+0x2ac/0x2e0
> [ 65.831789] [<ffffffff812c796a>] ? delay_tsc+0x4a/0x80
> [ 65.837625] [<ffffffff81024e1f>] do_machine_check+0xbaf/0xbf0
> [ 65.844138] [<ffffffff813365d7>] ? intel_idle+0xc7/0x150
> [ 65.850166] [<ffffffff8156f03f>] machine_check+0x1f/0x30
> [ 65.856195] [<ffffffff813365d7>] ? intel_idle+0xc7/0x150
> [ 65.862222] <<EOE>> [<ffffffff814283d5>]
> cpuidle_enter_state+0x55/0x170
> [ 65.869823] [<ffffffff814285a7>] cpuidle_enter+0x17/0x20
> [ 65.875852] [<ffffffff81097b08>] cpu_startup_entry+0x2d8/0x370
> [ 65.882467] [<ffffffff8102fe29>] start_secondary+0x159/0x180
>
> There's __drm_modeset_lock_all() which Daniel Vetter introduced for this
> purpose. We can leverage that without reinventing anything. This patch
> works with the latest kernel.
>
> Signed-off-by: Rui Wang <[email protected]>
> ---
> drivers/gpu/drm/drm_fb_helper.c | 8 ++++++--
> 1 files changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_fb_helper.c
> b/drivers/gpu/drm/drm_fb_helper.c
> index 0c0c39b..70dd2f4 100644
> --- a/drivers/gpu/drm/drm_fb_helper.c
> +++ b/drivers/gpu/drm/drm_fb_helper.c
> @@ -732,7 +732,9 @@ int drm_fb_helper_setcmap(struct fb_cmap *cmap, struct
> fb_info *info)
> int i, j, rc = 0;
> int start;
>
> - drm_modeset_lock_all(dev);
> + if (__drm_modeset_lock_all(dev, !!oops_in_progress)) {
> + return -EBUSY;
> + }
> if (!drm_fb_helper_is_bound(fb_helper)) {
> drm_modeset_unlock_all(dev);
> return -EBUSY;
> @@ -910,7 +912,9 @@ int drm_fb_helper_pan_display(struct fb_var_screeninfo
> *var,
> int ret = 0;
> int i;
>
> - drm_modeset_lock_all(dev);
> + if (__drm_modeset_lock_all(dev, !!oops_in_progress)) {
> + return -EBUSY;
> + }
> if (!drm_fb_helper_is_bound(fb_helper)) {
> drm_modeset_unlock_all(dev);
> return -EBUSY;
> --
> 1.7.5.4
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to [email protected]
> More majordomo info at http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.tux.org/lkml/
>
Hi All,
Any comment ? Or any better idea how this should be fixed?
Regards,
Rui
---------- Forwarded message ----------
From: [email protected]
Date: Thu, 4 Dec 2014 22:11:35 +0800
Subject: [PATCH] drm: fb helper should avoid sleeping in panic context
To: [email protected], [email protected], [email protected],
[email protected], [email protected], [email protected]
Cc: [email protected]
From: Rui Wang <[email protected]>
There are still some places in the fb helper that need to avoid
sleeping in panic context. Here's an example:
[ 65.615496] bad: scheduling from the idle thread!
[ 65.620747] CPU: 92 PID: 0 Comm: swapper/92 Tainted: G M E
3.18.0-rc4-7-default+ #20
[ 65.630364] Hardware name: Intel Corporation BRICKLAND/BRICKLAND,
BIOS BRHSXSD1.86B.0056.R01.1409242327 09/24/2014
[ 65.641923] ffff88087f693d80 ffff88087f689878 ffffffff81566db9
0000000000000000
[ 65.650226] ffff88087f693d80 ffff88087f689898 ffffffff810871ff
ffff88046eb3e0d0
[ 65.658527] ffff88087f693d80 ffff88087f6898c8 ffffffff8107c1fa
000000017f6898b8
[ 65.666830] Call Trace:
[ 65.669557] <#MC> [<ffffffff81566db9>] dump_stack+0x46/0x58
[ 65.675994] [<ffffffff810871ff>] dequeue_task_idle+0x2f/0x40
[ 65.682412] [<ffffffff8107c1fa>] dequeue_task+0x5a/0x80
[ 65.688345] [<ffffffff810804f3>] deactivate_task+0x23/0x30
[ 65.694569] [<ffffffff81569050>] __schedule+0x580/0x7f0
[ 65.700502] [<ffffffff81569739>] schedule_preempt_disabled+0x29/0x70
[ 65.707696] [<ffffffff8156abb6>] __ww_mutex_lock_slowpath+0xb8/0x162
[ 65.714891] [<ffffffff8156acb3>] __ww_mutex_lock+0x53/0x85
[ 65.721125] [<ffffffffa00b3a5d>] drm_modeset_lock+0x3d/0x110 [drm]
[ 65.728132] [<ffffffffa00b3c2a>] __drm_modeset_lock_all+0x8a/0x120 [drm]
[ 65.735721] [<ffffffffa00b3cd0>] drm_modeset_lock_all+0x10/0x30 [drm]
[ 65.743015] [<ffffffffa01af8bf>]
drm_fb_helper_pan_display+0x2f/0xf0 [drm_kms_helper]
[ 65.751857] [<ffffffff8132bd21>] fb_pan_display+0xd1/0x1a0
[ 65.758081] [<ffffffff81326010>] bit_update_start+0x20/0x50
[ 65.764400] [<ffffffff813259f2>] fbcon_switch+0x3a2/0x550
[ 65.770528] [<ffffffff813a01c9>] redraw_screen+0x189/0x240
[ 65.776750] [<ffffffff81322f8a>] fbcon_blank+0x20a/0x2d0
[ 65.782778] [<ffffffff8137d359>] ? erst_writer+0x209/0x330
[ 65.789002] [<ffffffff810ba2f3>] ? internal_add_timer+0x63/0x80
[ 65.795710] [<ffffffff810bc137>] ? mod_timer+0x127/0x1e0
[ 65.801740] [<ffffffff813a0cd8>] do_unblank_screen+0xa8/0x1d0
[ 65.808255] [<ffffffff813a0e10>] unblank_screen+0x10/0x20
[ 65.814381] [<ffffffff812ca0d9>] bust_spinlocks+0x19/0x40
[ 65.820508] [<ffffffff81561ca7>] panic+0x106/0x1f5
[ 65.825955] [<ffffffff8102336c>] mce_panic+0x2ac/0x2e0
[ 65.831789] [<ffffffff812c796a>] ? delay_tsc+0x4a/0x80
[ 65.837625] [<ffffffff81024e1f>] do_machine_check+0xbaf/0xbf0
[ 65.844138] [<ffffffff813365d7>] ? intel_idle+0xc7/0x150
[ 65.850166] [<ffffffff8156f03f>] machine_check+0x1f/0x30
[ 65.856195] [<ffffffff813365d7>] ? intel_idle+0xc7/0x150
[ 65.862222] <<EOE>> [<ffffffff814283d5>] cpuidle_enter_state+0x55/0x170
[ 65.869823] [<ffffffff814285a7>] cpuidle_enter+0x17/0x20
[ 65.875852] [<ffffffff81097b08>] cpu_startup_entry+0x2d8/0x370
[ 65.882467] [<ffffffff8102fe29>] start_secondary+0x159/0x180
There's __drm_modeset_lock_all() which Daniel Vetter introduced for this
purpose. We can leverage that without reinventing anything. This patch
works with the latest kernel.
Signed-off-by: Rui Wang <[email protected]>
---
drivers/gpu/drm/drm_fb_helper.c | 8 ++++++--
1 files changed, 6 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index 0c0c39b..70dd2f4 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -732,7 +732,9 @@ int drm_fb_helper_setcmap(struct fb_cmap *cmap,
struct fb_info *info)
int i, j, rc = 0;
int start;
- drm_modeset_lock_all(dev);
+ if (__drm_modeset_lock_all(dev, !!oops_in_progress)) {
+ return -EBUSY;
+ }
if (!drm_fb_helper_is_bound(fb_helper)) {
drm_modeset_unlock_all(dev);
return -EBUSY;
@@ -910,7 +912,9 @@ int drm_fb_helper_pan_display(struct fb_var_screeninfo *var,
int ret = 0;
int i;
- drm_modeset_lock_all(dev);
+ if (__drm_modeset_lock_all(dev, !!oops_in_progress)) {
+ return -EBUSY;
+ }
if (!drm_fb_helper_is_bound(fb_helper)) {
drm_modeset_unlock_all(dev);
return -EBUSY;
--
1.7.5.4
perhaps fb helpers could use __drm_modeset_lock_all() w/ trylock=true
in panic context?
BR,
-R
On Tue, Dec 9, 2014 at 7:09 PM, rui wang <[email protected]> wrote:
> Hi All,
>
> Any comment ? Or any better idea how this should be fixed?
>
> Regards,
> Rui
>
> ---------- Forwarded message ----------
> From: [email protected]
> Date: Thu, 4 Dec 2014 22:11:35 +0800
> Subject: [PATCH] drm: fb helper should avoid sleeping in panic context
> To: [email protected], [email protected], [email protected],
> [email protected], [email protected], [email protected]
> Cc: [email protected]
>
> From: Rui Wang <[email protected]>
>
> There are still some places in the fb helper that need to avoid
> sleeping in panic context. Here's an example:
>
> [ 65.615496] bad: scheduling from the idle thread!
> [ 65.620747] CPU: 92 PID: 0 Comm: swapper/92 Tainted: G M E
> 3.18.0-rc4-7-default+ #20
>
> [ 65.630364] Hardware name: Intel Corporation BRICKLAND/BRICKLAND,
> BIOS BRHSXSD1.86B.0056.R01.1409242327 09/24/2014
> [ 65.641923] ffff88087f693d80 ffff88087f689878 ffffffff81566db9
> 0000000000000000
> [ 65.650226] ffff88087f693d80 ffff88087f689898 ffffffff810871ff
> ffff88046eb3e0d0
> [ 65.658527] ffff88087f693d80 ffff88087f6898c8 ffffffff8107c1fa
> 000000017f6898b8
> [ 65.666830] Call Trace:
> [ 65.669557] <#MC> [<ffffffff81566db9>] dump_stack+0x46/0x58
> [ 65.675994] [<ffffffff810871ff>] dequeue_task_idle+0x2f/0x40
> [ 65.682412] [<ffffffff8107c1fa>] dequeue_task+0x5a/0x80
> [ 65.688345] [<ffffffff810804f3>] deactivate_task+0x23/0x30
> [ 65.694569] [<ffffffff81569050>] __schedule+0x580/0x7f0
> [ 65.700502] [<ffffffff81569739>] schedule_preempt_disabled+0x29/0x70
> [ 65.707696] [<ffffffff8156abb6>] __ww_mutex_lock_slowpath+0xb8/0x162
> [ 65.714891] [<ffffffff8156acb3>] __ww_mutex_lock+0x53/0x85
> [ 65.721125] [<ffffffffa00b3a5d>] drm_modeset_lock+0x3d/0x110 [drm]
> [ 65.728132] [<ffffffffa00b3c2a>] __drm_modeset_lock_all+0x8a/0x120 [drm]
> [ 65.735721] [<ffffffffa00b3cd0>] drm_modeset_lock_all+0x10/0x30 [drm]
> [ 65.743015] [<ffffffffa01af8bf>]
> drm_fb_helper_pan_display+0x2f/0xf0 [drm_kms_helper]
> [ 65.751857] [<ffffffff8132bd21>] fb_pan_display+0xd1/0x1a0
> [ 65.758081] [<ffffffff81326010>] bit_update_start+0x20/0x50
> [ 65.764400] [<ffffffff813259f2>] fbcon_switch+0x3a2/0x550
> [ 65.770528] [<ffffffff813a01c9>] redraw_screen+0x189/0x240
> [ 65.776750] [<ffffffff81322f8a>] fbcon_blank+0x20a/0x2d0
> [ 65.782778] [<ffffffff8137d359>] ? erst_writer+0x209/0x330
> [ 65.789002] [<ffffffff810ba2f3>] ? internal_add_timer+0x63/0x80
> [ 65.795710] [<ffffffff810bc137>] ? mod_timer+0x127/0x1e0
> [ 65.801740] [<ffffffff813a0cd8>] do_unblank_screen+0xa8/0x1d0
> [ 65.808255] [<ffffffff813a0e10>] unblank_screen+0x10/0x20
> [ 65.814381] [<ffffffff812ca0d9>] bust_spinlocks+0x19/0x40
> [ 65.820508] [<ffffffff81561ca7>] panic+0x106/0x1f5
> [ 65.825955] [<ffffffff8102336c>] mce_panic+0x2ac/0x2e0
> [ 65.831789] [<ffffffff812c796a>] ? delay_tsc+0x4a/0x80
> [ 65.837625] [<ffffffff81024e1f>] do_machine_check+0xbaf/0xbf0
> [ 65.844138] [<ffffffff813365d7>] ? intel_idle+0xc7/0x150
> [ 65.850166] [<ffffffff8156f03f>] machine_check+0x1f/0x30
> [ 65.856195] [<ffffffff813365d7>] ? intel_idle+0xc7/0x150
> [ 65.862222] <<EOE>> [<ffffffff814283d5>] cpuidle_enter_state+0x55/0x170
> [ 65.869823] [<ffffffff814285a7>] cpuidle_enter+0x17/0x20
> [ 65.875852] [<ffffffff81097b08>] cpu_startup_entry+0x2d8/0x370
> [ 65.882467] [<ffffffff8102fe29>] start_secondary+0x159/0x180
>
> There's __drm_modeset_lock_all() which Daniel Vetter introduced for this
> purpose. We can leverage that without reinventing anything. This patch
> works with the latest kernel.
>
> Signed-off-by: Rui Wang <[email protected]>
> ---
> drivers/gpu/drm/drm_fb_helper.c | 8 ++++++--
> 1 files changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
> index 0c0c39b..70dd2f4 100644
> --- a/drivers/gpu/drm/drm_fb_helper.c
> +++ b/drivers/gpu/drm/drm_fb_helper.c
> @@ -732,7 +732,9 @@ int drm_fb_helper_setcmap(struct fb_cmap *cmap,
> struct fb_info *info)
> int i, j, rc = 0;
> int start;
>
> - drm_modeset_lock_all(dev);
> + if (__drm_modeset_lock_all(dev, !!oops_in_progress)) {
> + return -EBUSY;
> + }
> if (!drm_fb_helper_is_bound(fb_helper)) {
> drm_modeset_unlock_all(dev);
> return -EBUSY;
> @@ -910,7 +912,9 @@ int drm_fb_helper_pan_display(struct fb_var_screeninfo *var,
> int ret = 0;
> int i;
>
> - drm_modeset_lock_all(dev);
> + if (__drm_modeset_lock_all(dev, !!oops_in_progress)) {
> + return -EBUSY;
> + }
> if (!drm_fb_helper_is_bound(fb_helper)) {
> drm_modeset_unlock_all(dev);
> return -EBUSY;
> --
> 1.7.5.4
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to [email protected]
> More majordomo info at http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.tux.org/lkml/
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to [email protected]
> More majordomo info at http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.tux.org/lkml/
Hi Rob,
Yes it's exactly what I'm doing. Please scroll down and review my patch.
Thanks
Rui
On 12/10/14, Rob Clark <[email protected]> wrote:
> perhaps fb helpers could use __drm_modeset_lock_all() w/ trylock=true
> in panic context?
>
> BR,
> -R
>
> On Tue, Dec 9, 2014 at 7:09 PM, rui wang <[email protected]> wrote:
>> Hi All,
>>
>> Any comment ? Or any better idea how this should be fixed?
>>
>> Regards,
>> Rui
>>
>> ---------- Forwarded message ----------
>> From: [email protected]
>> Date: Thu, 4 Dec 2014 22:11:35 +0800
>> Subject: [PATCH] drm: fb helper should avoid sleeping in panic context
>> To: [email protected], [email protected], [email protected],
>> [email protected], [email protected], [email protected]
>> Cc: [email protected]
>>
>> From: Rui Wang <[email protected]>
>>
>> There are still some places in the fb helper that need to avoid
>> sleeping in panic context. Here's an example:
>>
>> [ 65.615496] bad: scheduling from the idle thread!
>> [ 65.620747] CPU: 92 PID: 0 Comm: swapper/92 Tainted: G M E
>> 3.18.0-rc4-7-default+ #20
>>
>> [ 65.630364] Hardware name: Intel Corporation BRICKLAND/BRICKLAND,
>> BIOS BRHSXSD1.86B.0056.R01.1409242327 09/24/2014
>> [ 65.641923] ffff88087f693d80 ffff88087f689878 ffffffff81566db9
>> 0000000000000000
>> [ 65.650226] ffff88087f693d80 ffff88087f689898 ffffffff810871ff
>> ffff88046eb3e0d0
>> [ 65.658527] ffff88087f693d80 ffff88087f6898c8 ffffffff8107c1fa
>> 000000017f6898b8
>> [ 65.666830] Call Trace:
>> [ 65.669557] <#MC> [<ffffffff81566db9>] dump_stack+0x46/0x58
>> [ 65.675994] [<ffffffff810871ff>] dequeue_task_idle+0x2f/0x40
>> [ 65.682412] [<ffffffff8107c1fa>] dequeue_task+0x5a/0x80
>> [ 65.688345] [<ffffffff810804f3>] deactivate_task+0x23/0x30
>> [ 65.694569] [<ffffffff81569050>] __schedule+0x580/0x7f0
>> [ 65.700502] [<ffffffff81569739>] schedule_preempt_disabled+0x29/0x70
>> [ 65.707696] [<ffffffff8156abb6>] __ww_mutex_lock_slowpath+0xb8/0x162
>> [ 65.714891] [<ffffffff8156acb3>] __ww_mutex_lock+0x53/0x85
>> [ 65.721125] [<ffffffffa00b3a5d>] drm_modeset_lock+0x3d/0x110 [drm]
>> [ 65.728132] [<ffffffffa00b3c2a>] __drm_modeset_lock_all+0x8a/0x120
>> [drm]
>> [ 65.735721] [<ffffffffa00b3cd0>] drm_modeset_lock_all+0x10/0x30 [drm]
>> [ 65.743015] [<ffffffffa01af8bf>]
>> drm_fb_helper_pan_display+0x2f/0xf0 [drm_kms_helper]
>> [ 65.751857] [<ffffffff8132bd21>] fb_pan_display+0xd1/0x1a0
>> [ 65.758081] [<ffffffff81326010>] bit_update_start+0x20/0x50
>> [ 65.764400] [<ffffffff813259f2>] fbcon_switch+0x3a2/0x550
>> [ 65.770528] [<ffffffff813a01c9>] redraw_screen+0x189/0x240
>> [ 65.776750] [<ffffffff81322f8a>] fbcon_blank+0x20a/0x2d0
>> [ 65.782778] [<ffffffff8137d359>] ? erst_writer+0x209/0x330
>> [ 65.789002] [<ffffffff810ba2f3>] ? internal_add_timer+0x63/0x80
>> [ 65.795710] [<ffffffff810bc137>] ? mod_timer+0x127/0x1e0
>> [ 65.801740] [<ffffffff813a0cd8>] do_unblank_screen+0xa8/0x1d0
>> [ 65.808255] [<ffffffff813a0e10>] unblank_screen+0x10/0x20
>> [ 65.814381] [<ffffffff812ca0d9>] bust_spinlocks+0x19/0x40
>> [ 65.820508] [<ffffffff81561ca7>] panic+0x106/0x1f5
>> [ 65.825955] [<ffffffff8102336c>] mce_panic+0x2ac/0x2e0
>> [ 65.831789] [<ffffffff812c796a>] ? delay_tsc+0x4a/0x80
>> [ 65.837625] [<ffffffff81024e1f>] do_machine_check+0xbaf/0xbf0
>> [ 65.844138] [<ffffffff813365d7>] ? intel_idle+0xc7/0x150
>> [ 65.850166] [<ffffffff8156f03f>] machine_check+0x1f/0x30
>> [ 65.856195] [<ffffffff813365d7>] ? intel_idle+0xc7/0x150
>> [ 65.862222] <<EOE>> [<ffffffff814283d5>]
>> cpuidle_enter_state+0x55/0x170
>> [ 65.869823] [<ffffffff814285a7>] cpuidle_enter+0x17/0x20
>> [ 65.875852] [<ffffffff81097b08>] cpu_startup_entry+0x2d8/0x370
>> [ 65.882467] [<ffffffff8102fe29>] start_secondary+0x159/0x180
>>
>> There's __drm_modeset_lock_all() which Daniel Vetter introduced for this
>> purpose. We can leverage that without reinventing anything. This patch
>> works with the latest kernel.
>>
>> Signed-off-by: Rui Wang <[email protected]>
>> ---
>> drivers/gpu/drm/drm_fb_helper.c | 8 ++++++--
>> 1 files changed, 6 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/drm_fb_helper.c
>> b/drivers/gpu/drm/drm_fb_helper.c
>> index 0c0c39b..70dd2f4 100644
>> --- a/drivers/gpu/drm/drm_fb_helper.c
>> +++ b/drivers/gpu/drm/drm_fb_helper.c
>> @@ -732,7 +732,9 @@ int drm_fb_helper_setcmap(struct fb_cmap *cmap,
>> struct fb_info *info)
>> int i, j, rc = 0;
>> int start;
>>
>> - drm_modeset_lock_all(dev);
>> + if (__drm_modeset_lock_all(dev, !!oops_in_progress)) {
>> + return -EBUSY;
>> + }
>> if (!drm_fb_helper_is_bound(fb_helper)) {
>> drm_modeset_unlock_all(dev);
>> return -EBUSY;
>> @@ -910,7 +912,9 @@ int drm_fb_helper_pan_display(struct fb_var_screeninfo
>> *var,
>> int ret = 0;
>> int i;
>>
>> - drm_modeset_lock_all(dev);
>> + if (__drm_modeset_lock_all(dev, !!oops_in_progress)) {
>> + return -EBUSY;
>> + }
>> if (!drm_fb_helper_is_bound(fb_helper)) {
>> drm_modeset_unlock_all(dev);
>> return -EBUSY;
>> --
>> 1.7.5.4
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-kernel"
>> in
>> the body of a message to [email protected]
>> More majordomo info at http://vger.kernel.org/majordomo-info.html
>> Please read the FAQ at http://www.tux.org/lkml/
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-kernel"
>> in
>> the body of a message to [email protected]
>> More majordomo info at http://vger.kernel.org/majordomo-info.html
>> Please read the FAQ at http://www.tux.org/lkml/
>
oh, whoops.. gmail hiding quoted text..
yeah, that looks sane,
Reviewed-by: Rob Clark <[email protected]>
On Tue, Dec 9, 2014 at 7:55 PM, rui wang <[email protected]> wrote:
> Hi Rob,
> Yes it's exactly what I'm doing. Please scroll down and review my patch.
>
> Thanks
> Rui
>
> On 12/10/14, Rob Clark <[email protected]> wrote:
>> perhaps fb helpers could use __drm_modeset_lock_all() w/ trylock=true
>> in panic context?
>>
>> BR,
>> -R
>>
>> On Tue, Dec 9, 2014 at 7:09 PM, rui wang <[email protected]> wrote:
>>> Hi All,
>>>
>>> Any comment ? Or any better idea how this should be fixed?
>>>
>>> Regards,
>>> Rui
>>>
>>> ---------- Forwarded message ----------
>>> From: [email protected]
>>> Date: Thu, 4 Dec 2014 22:11:35 +0800
>>> Subject: [PATCH] drm: fb helper should avoid sleeping in panic context
>>> To: [email protected], [email protected], [email protected],
>>> [email protected], [email protected], [email protected]
>>> Cc: [email protected]
>>>
>>> From: Rui Wang <[email protected]>
>>>
>>> There are still some places in the fb helper that need to avoid
>>> sleeping in panic context. Here's an example:
>>>
>>> [ 65.615496] bad: scheduling from the idle thread!
>>> [ 65.620747] CPU: 92 PID: 0 Comm: swapper/92 Tainted: G M E
>>> 3.18.0-rc4-7-default+ #20
>>>
>>> [ 65.630364] Hardware name: Intel Corporation BRICKLAND/BRICKLAND,
>>> BIOS BRHSXSD1.86B.0056.R01.1409242327 09/24/2014
>>> [ 65.641923] ffff88087f693d80 ffff88087f689878 ffffffff81566db9
>>> 0000000000000000
>>> [ 65.650226] ffff88087f693d80 ffff88087f689898 ffffffff810871ff
>>> ffff88046eb3e0d0
>>> [ 65.658527] ffff88087f693d80 ffff88087f6898c8 ffffffff8107c1fa
>>> 000000017f6898b8
>>> [ 65.666830] Call Trace:
>>> [ 65.669557] <#MC> [<ffffffff81566db9>] dump_stack+0x46/0x58
>>> [ 65.675994] [<ffffffff810871ff>] dequeue_task_idle+0x2f/0x40
>>> [ 65.682412] [<ffffffff8107c1fa>] dequeue_task+0x5a/0x80
>>> [ 65.688345] [<ffffffff810804f3>] deactivate_task+0x23/0x30
>>> [ 65.694569] [<ffffffff81569050>] __schedule+0x580/0x7f0
>>> [ 65.700502] [<ffffffff81569739>] schedule_preempt_disabled+0x29/0x70
>>> [ 65.707696] [<ffffffff8156abb6>] __ww_mutex_lock_slowpath+0xb8/0x162
>>> [ 65.714891] [<ffffffff8156acb3>] __ww_mutex_lock+0x53/0x85
>>> [ 65.721125] [<ffffffffa00b3a5d>] drm_modeset_lock+0x3d/0x110 [drm]
>>> [ 65.728132] [<ffffffffa00b3c2a>] __drm_modeset_lock_all+0x8a/0x120
>>> [drm]
>>> [ 65.735721] [<ffffffffa00b3cd0>] drm_modeset_lock_all+0x10/0x30 [drm]
>>> [ 65.743015] [<ffffffffa01af8bf>]
>>> drm_fb_helper_pan_display+0x2f/0xf0 [drm_kms_helper]
>>> [ 65.751857] [<ffffffff8132bd21>] fb_pan_display+0xd1/0x1a0
>>> [ 65.758081] [<ffffffff81326010>] bit_update_start+0x20/0x50
>>> [ 65.764400] [<ffffffff813259f2>] fbcon_switch+0x3a2/0x550
>>> [ 65.770528] [<ffffffff813a01c9>] redraw_screen+0x189/0x240
>>> [ 65.776750] [<ffffffff81322f8a>] fbcon_blank+0x20a/0x2d0
>>> [ 65.782778] [<ffffffff8137d359>] ? erst_writer+0x209/0x330
>>> [ 65.789002] [<ffffffff810ba2f3>] ? internal_add_timer+0x63/0x80
>>> [ 65.795710] [<ffffffff810bc137>] ? mod_timer+0x127/0x1e0
>>> [ 65.801740] [<ffffffff813a0cd8>] do_unblank_screen+0xa8/0x1d0
>>> [ 65.808255] [<ffffffff813a0e10>] unblank_screen+0x10/0x20
>>> [ 65.814381] [<ffffffff812ca0d9>] bust_spinlocks+0x19/0x40
>>> [ 65.820508] [<ffffffff81561ca7>] panic+0x106/0x1f5
>>> [ 65.825955] [<ffffffff8102336c>] mce_panic+0x2ac/0x2e0
>>> [ 65.831789] [<ffffffff812c796a>] ? delay_tsc+0x4a/0x80
>>> [ 65.837625] [<ffffffff81024e1f>] do_machine_check+0xbaf/0xbf0
>>> [ 65.844138] [<ffffffff813365d7>] ? intel_idle+0xc7/0x150
>>> [ 65.850166] [<ffffffff8156f03f>] machine_check+0x1f/0x30
>>> [ 65.856195] [<ffffffff813365d7>] ? intel_idle+0xc7/0x150
>>> [ 65.862222] <<EOE>> [<ffffffff814283d5>]
>>> cpuidle_enter_state+0x55/0x170
>>> [ 65.869823] [<ffffffff814285a7>] cpuidle_enter+0x17/0x20
>>> [ 65.875852] [<ffffffff81097b08>] cpu_startup_entry+0x2d8/0x370
>>> [ 65.882467] [<ffffffff8102fe29>] start_secondary+0x159/0x180
>>>
>>> There's __drm_modeset_lock_all() which Daniel Vetter introduced for this
>>> purpose. We can leverage that without reinventing anything. This patch
>>> works with the latest kernel.
>>>
>>> Signed-off-by: Rui Wang <[email protected]>
>>> ---
>>> drivers/gpu/drm/drm_fb_helper.c | 8 ++++++--
>>> 1 files changed, 6 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/drm_fb_helper.c
>>> b/drivers/gpu/drm/drm_fb_helper.c
>>> index 0c0c39b..70dd2f4 100644
>>> --- a/drivers/gpu/drm/drm_fb_helper.c
>>> +++ b/drivers/gpu/drm/drm_fb_helper.c
>>> @@ -732,7 +732,9 @@ int drm_fb_helper_setcmap(struct fb_cmap *cmap,
>>> struct fb_info *info)
>>> int i, j, rc = 0;
>>> int start;
>>>
>>> - drm_modeset_lock_all(dev);
>>> + if (__drm_modeset_lock_all(dev, !!oops_in_progress)) {
>>> + return -EBUSY;
>>> + }
>>> if (!drm_fb_helper_is_bound(fb_helper)) {
>>> drm_modeset_unlock_all(dev);
>>> return -EBUSY;
>>> @@ -910,7 +912,9 @@ int drm_fb_helper_pan_display(struct fb_var_screeninfo
>>> *var,
>>> int ret = 0;
>>> int i;
>>>
>>> - drm_modeset_lock_all(dev);
>>> + if (__drm_modeset_lock_all(dev, !!oops_in_progress)) {
>>> + return -EBUSY;
>>> + }
>>> if (!drm_fb_helper_is_bound(fb_helper)) {
>>> drm_modeset_unlock_all(dev);
>>> return -EBUSY;
>>> --
>>> 1.7.5.4
>>>
>>> --
>>> To unsubscribe from this list: send the line "unsubscribe linux-kernel"
>>> in
>>> the body of a message to [email protected]
>>> More majordomo info at http://vger.kernel.org/majordomo-info.html
>>> Please read the FAQ at http://www.tux.org/lkml/
>>> --
>>> To unsubscribe from this list: send the line "unsubscribe linux-kernel"
>>> in
>>> the body of a message to [email protected]
>>> More majordomo info at http://vger.kernel.org/majordomo-info.html
>>> Please read the FAQ at http://www.tux.org/lkml/
>>
On Tue, Dec 09, 2014 at 08:05:21PM -0500, Rob Clark wrote:
> oh, whoops.. gmail hiding quoted text..
>
> yeah, that looks sane,
>
> Reviewed-by: Rob Clark <[email protected]>
>
> On Tue, Dec 9, 2014 at 7:55 PM, rui wang <[email protected]> wrote:
> > Hi Rob,
> > Yes it's exactly what I'm doing. Please scroll down and review my patch.
> >
> > Thanks
> > Rui
> >
> > On 12/10/14, Rob Clark <[email protected]> wrote:
> >> perhaps fb helpers could use __drm_modeset_lock_all() w/ trylock=true
> >> in panic context?
> >>
> >> BR,
> >> -R
> >>
> >> On Tue, Dec 9, 2014 at 7:09 PM, rui wang <[email protected]> wrote:
> >>> Hi All,
> >>>
> >>> Any comment ? Or any better idea how this should be fixed?
> >>>
> >>> Regards,
> >>> Rui
> >>>
Dear gmail-ers,
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?
Please stop the top-posting or use a mail client which doesn't
facilitate the idiocy.
Thanks.
--
Regards/Gruss,
Boris.
Sent from a fat crate under my desk. Formatting is fine.
--
From: Rui Wang <[email protected]>
There are still some places in the fb helper that need to avoid
sleeping in panic context. Here's an example:
[ 65.615496] bad: scheduling from the idle thread!
[ 65.620747] CPU: 92 PID: 0 Comm: swapper/92 Tainted: G M E 3.18.0-rc4-7-default+ #20
[ 65.630364] Hardware name: Intel Corporation BRICKLAND/BRICKLAND, BIOS
BRHSXSD1.86B.0056.R01.1409242327 09/24/2014
[ 65.641923] ffff88087f693d80 ffff88087f689878 ffffffff81566db9 0000000000000000
[ 65.650226] ffff88087f693d80 ffff88087f689898 ffffffff810871ff ffff88046eb3e0d0
[ 65.658527] ffff88087f693d80 ffff88087f6898c8 ffffffff8107c1fa 000000017f6898b8
[ 65.666830] Call Trace:
[ 65.669557] <#MC> [<ffffffff81566db9>] dump_stack+0x46/0x58
[ 65.675994] [<ffffffff810871ff>] dequeue_task_idle+0x2f/0x40
[ 65.682412] [<ffffffff8107c1fa>] dequeue_task+0x5a/0x80
[ 65.688345] [<ffffffff810804f3>] deactivate_task+0x23/0x30
[ 65.694569] [<ffffffff81569050>] __schedule+0x580/0x7f0
[ 65.700502] [<ffffffff81569739>] schedule_preempt_disabled+0x29/0x70
[ 65.707696] [<ffffffff8156abb6>] __ww_mutex_lock_slowpath+0xb8/0x162
[ 65.714891] [<ffffffff8156acb3>] __ww_mutex_lock+0x53/0x85
[ 65.721125] [<ffffffffa00b3a5d>] drm_modeset_lock+0x3d/0x110 [drm]
[ 65.728132] [<ffffffffa00b3c2a>] __drm_modeset_lock_all+0x8a/0x120 [drm]
[ 65.735721] [<ffffffffa00b3cd0>] drm_modeset_lock_all+0x10/0x30 [drm]
[ 65.743015] [<ffffffffa01af8bf>] drm_fb_helper_pan_display+0x2f/0xf0 [drm_kms_helper]
[ 65.751857] [<ffffffff8132bd21>] fb_pan_display+0xd1/0x1a0
[ 65.758081] [<ffffffff81326010>] bit_update_start+0x20/0x50
[ 65.764400] [<ffffffff813259f2>] fbcon_switch+0x3a2/0x550
[ 65.770528] [<ffffffff813a01c9>] redraw_screen+0x189/0x240
[ 65.776750] [<ffffffff81322f8a>] fbcon_blank+0x20a/0x2d0
[ 65.782778] [<ffffffff8137d359>] ? erst_writer+0x209/0x330
[ 65.789002] [<ffffffff810ba2f3>] ? internal_add_timer+0x63/0x80
[ 65.795710] [<ffffffff810bc137>] ? mod_timer+0x127/0x1e0
[ 65.801740] [<ffffffff813a0cd8>] do_unblank_screen+0xa8/0x1d0
[ 65.808255] [<ffffffff813a0e10>] unblank_screen+0x10/0x20
[ 65.814381] [<ffffffff812ca0d9>] bust_spinlocks+0x19/0x40
[ 65.820508] [<ffffffff81561ca7>] panic+0x106/0x1f5
[ 65.825955] [<ffffffff8102336c>] mce_panic+0x2ac/0x2e0
[ 65.831789] [<ffffffff812c796a>] ? delay_tsc+0x4a/0x80
[ 65.837625] [<ffffffff81024e1f>] do_machine_check+0xbaf/0xbf0
[ 65.844138] [<ffffffff813365d7>] ? intel_idle+0xc7/0x150
[ 65.850166] [<ffffffff8156f03f>] machine_check+0x1f/0x30
[ 65.856195] [<ffffffff813365d7>] ? intel_idle+0xc7/0x150
[ 65.862222] <<EOE>> [<ffffffff814283d5>] cpuidle_enter_state+0x55/0x170
[ 65.869823] [<ffffffff814285a7>] cpuidle_enter+0x17/0x20
[ 65.875852] [<ffffffff81097b08>] cpu_startup_entry+0x2d8/0x370
[ 65.882467] [<ffffffff8102fe29>] start_secondary+0x159/0x180
There's __drm_modeset_lock_all() which Daniel Vetter introduced for this
purpose. We can leverage that without reinventing anything. This patch
works with the latest kernel.
Reviewed-by: Rob Clark <[email protected]>
Tested-by: Tony Luck <[email protected]>
Signed-off-by: Rui Wang <[email protected]>
---
Dave: I don't see this in any of your trees yet. Bug is really annoying
when testing machine check code because the above stack dumps just repeat
endlessly until I manually hit the reset button
drivers/gpu/drm/drm_fb_helper.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index 0c0c39bac23d..70dd2f4eb299 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -732,7 +732,9 @@ int drm_fb_helper_setcmap(struct fb_cmap *cmap, struct fb_info *info)
int i, j, rc = 0;
int start;
- drm_modeset_lock_all(dev);
+ if (__drm_modeset_lock_all(dev, !!oops_in_progress)) {
+ return -EBUSY;
+ }
if (!drm_fb_helper_is_bound(fb_helper)) {
drm_modeset_unlock_all(dev);
return -EBUSY;
@@ -910,7 +912,9 @@ int drm_fb_helper_pan_display(struct fb_var_screeninfo *var,
int ret = 0;
int i;
- drm_modeset_lock_all(dev);
+ if (__drm_modeset_lock_all(dev, !!oops_in_progress)) {
+ return -EBUSY;
+ }
if (!drm_fb_helper_is_bound(fb_helper)) {
drm_modeset_unlock_all(dev);
return -EBUSY;
--
2.1.0