Re: [syzbot] upstream boot error: WARNING in vkms_vblank_simulate

2021-03-16 Thread Daniel Vetter
On Fri, Mar 12, 2021 at 05:10:43PM +0100, Dmitry Vyukov wrote:
> On Fri, Mar 12, 2021 at 3:22 PM Daniel Vetter  wrote:
> >
> > On Fri, Mar 12, 2021 at 11:46:27AM +0100, Dmitry Vyukov wrote:
> > > On Fri, Mar 12, 2021 at 11:26 AM syzbot
> > >  wrote:
> > > >
> > > > Hello,
> > > >
> > > > syzbot found the following issue on:
> > > >
> > > > HEAD commit:f78d76e7 Merge tag 'drm-fixes-2021-03-12-1' of 
> > > > git://anong..
> > > > git tree:   upstream
> > > > console output: https://syzkaller.appspot.com/x/log.txt?x=11c16ba2d0
> > > > kernel config:  
> > > > https://syzkaller.appspot.com/x/.config?x=dc02c6afcb046874
> > > > dashboard link: 
> > > > https://syzkaller.appspot.com/bug?extid=333bd014262fd5d0a418
> > > > userspace arch: arm
> > > >
> > > > IMPORTANT: if you fix the issue, please add the following tag to the 
> > > > commit:
> > > > Reported-by: syzbot+333bd014262fd5d0a...@syzkaller.appspotmail.com
> > >
> > > This WARNING seems to be happening just randomly.
> > > It was already reported as:
> > >
> > > #syz dup: WARNING in vkms_vblank_simulate (2)
> > > https://syzkaller.appspot.com/bug?id=9b10491371879700d6a21c15684c2232ff015084
> > >
> > > It now has whooping 48589 crashes and also crashes slow qemu tcg 
> > > instances.
> >
> > Yeah your box is too slow. We're trying to simulate hw here, which means
> > if we can process less than 1 hrtimer per vblank (standard every 16ms)
> > then we scream, because things go very wrong with the simulated hw. And
> > the hrtimer is really not that big, all the expensive processing is pushed
> > to worker, where we have code to handle if it falls back too much.
> >
> > So either patch this out or make the code robust against a kernel that
> > somehow can't process a single hrtimer every 16ms.
> > -Daniel
> 
> Majority of these happen on the latest Intel CPUs. If that's not fast,
> then I don't know what' fast :)
> WARNING must not be used for timing-triggerable conditions. pr_warn is
> more appropriate here. I assume the call stack and the rest of the
> info that WARNING prints is completely useless, it's only the binary
> condition, right.

Hm, maybe we do have some bug somewhere left still. But yeah if pr_warn
does not trigger a full abort with syzbot then we can do that I guess.

Care to submit that pathc please with a short explainer why it upsets
syzbot?

Thanks, Daniel

> 
> 
> > > > [ cut here ]
> > > > WARNING: CPU: 0 PID: 0 at drivers/gpu/drm/vkms/vkms_crtc.c:21 
> > > > vkms_vblank_simulate+0x26c/0x2f4 drivers/gpu/drm/vkms/vkms_crtc.c:41
> > > > Modules linked in:
> > > > CPU: 0 PID: 0 Comm: swapper/0 Not tainted 
> > > > 5.12.0-rc2-syzkaller-00338-gf78d76e72a46 #0
> > > > Hardware name: linux,dummy-virt (DT)
> > > > pstate: 2085 (nzCv daIf -PAN -UAO -TCO BTYPE=--)
> > > > pc : vkms_vblank_simulate+0x26c/0x2f4 
> > > > drivers/gpu/drm/vkms/vkms_crtc.c:21
> > > > lr : hrtimer_forward_now include/linux/hrtimer.h:510 [inline]
> > > > lr : vkms_vblank_simulate+0x90/0x2f4 drivers/gpu/drm/vkms/vkms_crtc.c:19
> > > > sp : 6a693cd0
> > > > x29: 6a693cd0 x28: 0c9d1e58
> > > > x27: dfff8000 x26: 6a67f540
> > > > x25: 1fffed4cfeb1 x24: 1fffed4cfeaa
> > > > x23: 0c9d0d30 x22: 00fe4c00
> > > > x21: 6a67f540 x20: 0c9d0e58
> > > > x19: 0c9d1e58 x18: 6a6a1b48
> > > > x17: 1fffe1952345 x16: 
> > > > x15: 8000197bf810 x14: 1fffed4d2750
> > > > x13: 0001 x12: 0033
> > > > x11: 12fb4936 x10: 0007
> > > > x9 : 12fb4943 x8 : 800017d14c00
> > > > x7 : f1f1f1f1 x6 : dfff8000
> > > > x5 : 7fff x4 : 0008e44f6b90
> > > > x3 : 0008e54db790 x2 : 0008e44f6b90
> > > > x1 : 0008e54db790 x0 : 0002
> > > > Call trace:
> > > >  vkms_vblank_simulate+0x26c/0x2f4 drivers/gpu/drm/vkms/vkms_crtc.c:41
> > > >  __run_hrtimer kernel/time/hrtimer.c:1519 [inline]
> > > >  __hrtimer_run_queues+0x590/0xe40 kernel/time/hrtimer.c:1583
> > > >  hrtimer_interrupt+0x2d4/0x810 kernel/time/hrtimer.c:1645
> > > >  timer_handler drivers/clocksource/arm_arch_timer.c:647 [inline]
> > > >  arch_timer_handler_phys+0x4c/0x70 
> > > > drivers/clocksource/arm_arch_timer.c:665
> > > >  handle_percpu_devid_irq+0x19c/0x330 kernel/irq/chip.c:930
> > > >  generic_handle_irq_desc include/linux/irqdesc.h:158 [inline]
> > > >  generic_handle_irq kernel/irq/irqdesc.c:652 [inline]
> > > >  __handle_domain_irq+0x11c/0x1f0 kernel/irq/irqdesc.c:689
> > > >  handle_domain_irq include/linux/irqdesc.h:176 [inline]
> > > >  gic_handle_irq+0x5c/0x1b0 drivers/irqchip/irq-gic.c:370
> > > >  el1_irq+0xb4/0x180 arch/arm64/kernel/entry.S:669
> > > >  arch_local_irq_restore arch/arm64/include/asm/irqflags.h:124 [inline]
> > > >  queue_work_on+0x74/0x110 kernel/workqueue.c:1528
> > > >  queue_work include/linux/workqueue.h:507 [inline]
> > > >  

Re: [syzbot] upstream boot error: WARNING in vkms_vblank_simulate

2021-03-12 Thread Dmitry Vyukov
On Fri, Mar 12, 2021 at 3:22 PM Daniel Vetter  wrote:
>
> On Fri, Mar 12, 2021 at 11:46:27AM +0100, Dmitry Vyukov wrote:
> > On Fri, Mar 12, 2021 at 11:26 AM syzbot
> >  wrote:
> > >
> > > Hello,
> > >
> > > syzbot found the following issue on:
> > >
> > > HEAD commit:f78d76e7 Merge tag 'drm-fixes-2021-03-12-1' of 
> > > git://anong..
> > > git tree:   upstream
> > > console output: https://syzkaller.appspot.com/x/log.txt?x=11c16ba2d0
> > > kernel config:  https://syzkaller.appspot.com/x/.config?x=dc02c6afcb046874
> > > dashboard link: 
> > > https://syzkaller.appspot.com/bug?extid=333bd014262fd5d0a418
> > > userspace arch: arm
> > >
> > > IMPORTANT: if you fix the issue, please add the following tag to the 
> > > commit:
> > > Reported-by: syzbot+333bd014262fd5d0a...@syzkaller.appspotmail.com
> >
> > This WARNING seems to be happening just randomly.
> > It was already reported as:
> >
> > #syz dup: WARNING in vkms_vblank_simulate (2)
> > https://syzkaller.appspot.com/bug?id=9b10491371879700d6a21c15684c2232ff015084
> >
> > It now has whooping 48589 crashes and also crashes slow qemu tcg instances.
>
> Yeah your box is too slow. We're trying to simulate hw here, which means
> if we can process less than 1 hrtimer per vblank (standard every 16ms)
> then we scream, because things go very wrong with the simulated hw. And
> the hrtimer is really not that big, all the expensive processing is pushed
> to worker, where we have code to handle if it falls back too much.
>
> So either patch this out or make the code robust against a kernel that
> somehow can't process a single hrtimer every 16ms.
> -Daniel

Majority of these happen on the latest Intel CPUs. If that's not fast,
then I don't know what' fast :)
WARNING must not be used for timing-triggerable conditions. pr_warn is
more appropriate here. I assume the call stack and the rest of the
info that WARNING prints is completely useless, it's only the binary
condition, right.


> > > [ cut here ]
> > > WARNING: CPU: 0 PID: 0 at drivers/gpu/drm/vkms/vkms_crtc.c:21 
> > > vkms_vblank_simulate+0x26c/0x2f4 drivers/gpu/drm/vkms/vkms_crtc.c:41
> > > Modules linked in:
> > > CPU: 0 PID: 0 Comm: swapper/0 Not tainted 
> > > 5.12.0-rc2-syzkaller-00338-gf78d76e72a46 #0
> > > Hardware name: linux,dummy-virt (DT)
> > > pstate: 2085 (nzCv daIf -PAN -UAO -TCO BTYPE=--)
> > > pc : vkms_vblank_simulate+0x26c/0x2f4 drivers/gpu/drm/vkms/vkms_crtc.c:21
> > > lr : hrtimer_forward_now include/linux/hrtimer.h:510 [inline]
> > > lr : vkms_vblank_simulate+0x90/0x2f4 drivers/gpu/drm/vkms/vkms_crtc.c:19
> > > sp : 6a693cd0
> > > x29: 6a693cd0 x28: 0c9d1e58
> > > x27: dfff8000 x26: 6a67f540
> > > x25: 1fffed4cfeb1 x24: 1fffed4cfeaa
> > > x23: 0c9d0d30 x22: 00fe4c00
> > > x21: 6a67f540 x20: 0c9d0e58
> > > x19: 0c9d1e58 x18: 6a6a1b48
> > > x17: 1fffe1952345 x16: 
> > > x15: 8000197bf810 x14: 1fffed4d2750
> > > x13: 0001 x12: 0033
> > > x11: 12fb4936 x10: 0007
> > > x9 : 12fb4943 x8 : 800017d14c00
> > > x7 : f1f1f1f1 x6 : dfff8000
> > > x5 : 7fff x4 : 0008e44f6b90
> > > x3 : 0008e54db790 x2 : 0008e44f6b90
> > > x1 : 0008e54db790 x0 : 0002
> > > Call trace:
> > >  vkms_vblank_simulate+0x26c/0x2f4 drivers/gpu/drm/vkms/vkms_crtc.c:41
> > >  __run_hrtimer kernel/time/hrtimer.c:1519 [inline]
> > >  __hrtimer_run_queues+0x590/0xe40 kernel/time/hrtimer.c:1583
> > >  hrtimer_interrupt+0x2d4/0x810 kernel/time/hrtimer.c:1645
> > >  timer_handler drivers/clocksource/arm_arch_timer.c:647 [inline]
> > >  arch_timer_handler_phys+0x4c/0x70 
> > > drivers/clocksource/arm_arch_timer.c:665
> > >  handle_percpu_devid_irq+0x19c/0x330 kernel/irq/chip.c:930
> > >  generic_handle_irq_desc include/linux/irqdesc.h:158 [inline]
> > >  generic_handle_irq kernel/irq/irqdesc.c:652 [inline]
> > >  __handle_domain_irq+0x11c/0x1f0 kernel/irq/irqdesc.c:689
> > >  handle_domain_irq include/linux/irqdesc.h:176 [inline]
> > >  gic_handle_irq+0x5c/0x1b0 drivers/irqchip/irq-gic.c:370
> > >  el1_irq+0xb4/0x180 arch/arm64/kernel/entry.S:669
> > >  arch_local_irq_restore arch/arm64/include/asm/irqflags.h:124 [inline]
> > >  queue_work_on+0x74/0x110 kernel/workqueue.c:1528
> > >  queue_work include/linux/workqueue.h:507 [inline]
> > >  cursor_timer_handler+0x64/0x100 drivers/video/fbdev/core/fbcon.c:397
> > >  call_timer_fn+0x1d4/0x9c4 kernel/time/timer.c:1431
> > >  expire_timers kernel/time/timer.c:1476 [inline]
> > >  __run_timers.part.0+0x530/0xa00 kernel/time/timer.c:1745
> > >  __run_timers kernel/time/timer.c:1726 [inline]
> > >  run_timer_softirq+0xa4/0x1a0 kernel/time/timer.c:1758
> > >  _stext+0x2b4/0x1084
> > >  do_softirq_own_stack include/asm-generic/softirq_stack.h:10 [inline]
> > >  invoke_softirq kernel/softirq.c:228 [inline]
> > >  

Re: [syzbot] upstream boot error: WARNING in vkms_vblank_simulate

2021-03-12 Thread Daniel Vetter
On Fri, Mar 12, 2021 at 11:46:27AM +0100, Dmitry Vyukov wrote:
> On Fri, Mar 12, 2021 at 11:26 AM syzbot
>  wrote:
> >
> > Hello,
> >
> > syzbot found the following issue on:
> >
> > HEAD commit:f78d76e7 Merge tag 'drm-fixes-2021-03-12-1' of git://anong..
> > git tree:   upstream
> > console output: https://syzkaller.appspot.com/x/log.txt?x=11c16ba2d0
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=dc02c6afcb046874
> > dashboard link: https://syzkaller.appspot.com/bug?extid=333bd014262fd5d0a418
> > userspace arch: arm
> >
> > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > Reported-by: syzbot+333bd014262fd5d0a...@syzkaller.appspotmail.com
> 
> This WARNING seems to be happening just randomly.
> It was already reported as:
> 
> #syz dup: WARNING in vkms_vblank_simulate (2)
> https://syzkaller.appspot.com/bug?id=9b10491371879700d6a21c15684c2232ff015084
> 
> It now has whooping 48589 crashes and also crashes slow qemu tcg instances.

Yeah your box is too slow. We're trying to simulate hw here, which means
if we can process less than 1 hrtimer per vblank (standard every 16ms)
then we scream, because things go very wrong with the simulated hw. And
the hrtimer is really not that big, all the expensive processing is pushed
to worker, where we have code to handle if it falls back too much.

So either patch this out or make the code robust against a kernel that
somehow can't process a single hrtimer every 16ms.
-Daniel

> 
> 
> 
> > [ cut here ]
> > WARNING: CPU: 0 PID: 0 at drivers/gpu/drm/vkms/vkms_crtc.c:21 
> > vkms_vblank_simulate+0x26c/0x2f4 drivers/gpu/drm/vkms/vkms_crtc.c:41
> > Modules linked in:
> > CPU: 0 PID: 0 Comm: swapper/0 Not tainted 
> > 5.12.0-rc2-syzkaller-00338-gf78d76e72a46 #0
> > Hardware name: linux,dummy-virt (DT)
> > pstate: 2085 (nzCv daIf -PAN -UAO -TCO BTYPE=--)
> > pc : vkms_vblank_simulate+0x26c/0x2f4 drivers/gpu/drm/vkms/vkms_crtc.c:21
> > lr : hrtimer_forward_now include/linux/hrtimer.h:510 [inline]
> > lr : vkms_vblank_simulate+0x90/0x2f4 drivers/gpu/drm/vkms/vkms_crtc.c:19
> > sp : 6a693cd0
> > x29: 6a693cd0 x28: 0c9d1e58
> > x27: dfff8000 x26: 6a67f540
> > x25: 1fffed4cfeb1 x24: 1fffed4cfeaa
> > x23: 0c9d0d30 x22: 00fe4c00
> > x21: 6a67f540 x20: 0c9d0e58
> > x19: 0c9d1e58 x18: 6a6a1b48
> > x17: 1fffe1952345 x16: 
> > x15: 8000197bf810 x14: 1fffed4d2750
> > x13: 0001 x12: 0033
> > x11: 12fb4936 x10: 0007
> > x9 : 12fb4943 x8 : 800017d14c00
> > x7 : f1f1f1f1 x6 : dfff8000
> > x5 : 7fff x4 : 0008e44f6b90
> > x3 : 0008e54db790 x2 : 0008e44f6b90
> > x1 : 0008e54db790 x0 : 0002
> > Call trace:
> >  vkms_vblank_simulate+0x26c/0x2f4 drivers/gpu/drm/vkms/vkms_crtc.c:41
> >  __run_hrtimer kernel/time/hrtimer.c:1519 [inline]
> >  __hrtimer_run_queues+0x590/0xe40 kernel/time/hrtimer.c:1583
> >  hrtimer_interrupt+0x2d4/0x810 kernel/time/hrtimer.c:1645
> >  timer_handler drivers/clocksource/arm_arch_timer.c:647 [inline]
> >  arch_timer_handler_phys+0x4c/0x70 drivers/clocksource/arm_arch_timer.c:665
> >  handle_percpu_devid_irq+0x19c/0x330 kernel/irq/chip.c:930
> >  generic_handle_irq_desc include/linux/irqdesc.h:158 [inline]
> >  generic_handle_irq kernel/irq/irqdesc.c:652 [inline]
> >  __handle_domain_irq+0x11c/0x1f0 kernel/irq/irqdesc.c:689
> >  handle_domain_irq include/linux/irqdesc.h:176 [inline]
> >  gic_handle_irq+0x5c/0x1b0 drivers/irqchip/irq-gic.c:370
> >  el1_irq+0xb4/0x180 arch/arm64/kernel/entry.S:669
> >  arch_local_irq_restore arch/arm64/include/asm/irqflags.h:124 [inline]
> >  queue_work_on+0x74/0x110 kernel/workqueue.c:1528
> >  queue_work include/linux/workqueue.h:507 [inline]
> >  cursor_timer_handler+0x64/0x100 drivers/video/fbdev/core/fbcon.c:397
> >  call_timer_fn+0x1d4/0x9c4 kernel/time/timer.c:1431
> >  expire_timers kernel/time/timer.c:1476 [inline]
> >  __run_timers.part.0+0x530/0xa00 kernel/time/timer.c:1745
> >  __run_timers kernel/time/timer.c:1726 [inline]
> >  run_timer_softirq+0xa4/0x1a0 kernel/time/timer.c:1758
> >  _stext+0x2b4/0x1084
> >  do_softirq_own_stack include/asm-generic/softirq_stack.h:10 [inline]
> >  invoke_softirq kernel/softirq.c:228 [inline]
> >  __irq_exit_rcu+0x46c/0x510 kernel/softirq.c:422
> >  irq_exit+0x14/0x84 kernel/softirq.c:446
> >  __handle_domain_irq+0x120/0x1f0 kernel/irq/irqdesc.c:692
> >  handle_domain_irq include/linux/irqdesc.h:176 [inline]
> >  gic_handle_irq+0x5c/0x1b0 drivers/irqchip/irq-gic.c:370
> >  el1_irq+0xb4/0x180 arch/arm64/kernel/entry.S:669
> >  arch_local_irq_enable+0xc/0x14 arch/arm64/include/asm/irqflags.h:37
> >  default_idle_call+0x64/0xf4 kernel/sched/idle.c:112
> >  cpuidle_idle_call kernel/sched/idle.c:194 [inline]
> >  do_idle+0x38c/0x4ec kernel/sched/idle.c:300
> >  

Re: [syzbot] upstream boot error: WARNING in vkms_vblank_simulate

2021-03-12 Thread Dmitry Vyukov
On Fri, Mar 12, 2021 at 11:26 AM syzbot
 wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit:f78d76e7 Merge tag 'drm-fixes-2021-03-12-1' of git://anong..
> git tree:   upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=11c16ba2d0
> kernel config:  https://syzkaller.appspot.com/x/.config?x=dc02c6afcb046874
> dashboard link: https://syzkaller.appspot.com/bug?extid=333bd014262fd5d0a418
> userspace arch: arm
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+333bd014262fd5d0a...@syzkaller.appspotmail.com

This WARNING seems to be happening just randomly.
It was already reported as:

#syz dup: WARNING in vkms_vblank_simulate (2)
https://syzkaller.appspot.com/bug?id=9b10491371879700d6a21c15684c2232ff015084

It now has whooping 48589 crashes and also crashes slow qemu tcg instances.



> [ cut here ]
> WARNING: CPU: 0 PID: 0 at drivers/gpu/drm/vkms/vkms_crtc.c:21 
> vkms_vblank_simulate+0x26c/0x2f4 drivers/gpu/drm/vkms/vkms_crtc.c:41
> Modules linked in:
> CPU: 0 PID: 0 Comm: swapper/0 Not tainted 
> 5.12.0-rc2-syzkaller-00338-gf78d76e72a46 #0
> Hardware name: linux,dummy-virt (DT)
> pstate: 2085 (nzCv daIf -PAN -UAO -TCO BTYPE=--)
> pc : vkms_vblank_simulate+0x26c/0x2f4 drivers/gpu/drm/vkms/vkms_crtc.c:21
> lr : hrtimer_forward_now include/linux/hrtimer.h:510 [inline]
> lr : vkms_vblank_simulate+0x90/0x2f4 drivers/gpu/drm/vkms/vkms_crtc.c:19
> sp : 6a693cd0
> x29: 6a693cd0 x28: 0c9d1e58
> x27: dfff8000 x26: 6a67f540
> x25: 1fffed4cfeb1 x24: 1fffed4cfeaa
> x23: 0c9d0d30 x22: 00fe4c00
> x21: 6a67f540 x20: 0c9d0e58
> x19: 0c9d1e58 x18: 6a6a1b48
> x17: 1fffe1952345 x16: 
> x15: 8000197bf810 x14: 1fffed4d2750
> x13: 0001 x12: 0033
> x11: 12fb4936 x10: 0007
> x9 : 12fb4943 x8 : 800017d14c00
> x7 : f1f1f1f1 x6 : dfff8000
> x5 : 7fff x4 : 0008e44f6b90
> x3 : 0008e54db790 x2 : 0008e44f6b90
> x1 : 0008e54db790 x0 : 0002
> Call trace:
>  vkms_vblank_simulate+0x26c/0x2f4 drivers/gpu/drm/vkms/vkms_crtc.c:41
>  __run_hrtimer kernel/time/hrtimer.c:1519 [inline]
>  __hrtimer_run_queues+0x590/0xe40 kernel/time/hrtimer.c:1583
>  hrtimer_interrupt+0x2d4/0x810 kernel/time/hrtimer.c:1645
>  timer_handler drivers/clocksource/arm_arch_timer.c:647 [inline]
>  arch_timer_handler_phys+0x4c/0x70 drivers/clocksource/arm_arch_timer.c:665
>  handle_percpu_devid_irq+0x19c/0x330 kernel/irq/chip.c:930
>  generic_handle_irq_desc include/linux/irqdesc.h:158 [inline]
>  generic_handle_irq kernel/irq/irqdesc.c:652 [inline]
>  __handle_domain_irq+0x11c/0x1f0 kernel/irq/irqdesc.c:689
>  handle_domain_irq include/linux/irqdesc.h:176 [inline]
>  gic_handle_irq+0x5c/0x1b0 drivers/irqchip/irq-gic.c:370
>  el1_irq+0xb4/0x180 arch/arm64/kernel/entry.S:669
>  arch_local_irq_restore arch/arm64/include/asm/irqflags.h:124 [inline]
>  queue_work_on+0x74/0x110 kernel/workqueue.c:1528
>  queue_work include/linux/workqueue.h:507 [inline]
>  cursor_timer_handler+0x64/0x100 drivers/video/fbdev/core/fbcon.c:397
>  call_timer_fn+0x1d4/0x9c4 kernel/time/timer.c:1431
>  expire_timers kernel/time/timer.c:1476 [inline]
>  __run_timers.part.0+0x530/0xa00 kernel/time/timer.c:1745
>  __run_timers kernel/time/timer.c:1726 [inline]
>  run_timer_softirq+0xa4/0x1a0 kernel/time/timer.c:1758
>  _stext+0x2b4/0x1084
>  do_softirq_own_stack include/asm-generic/softirq_stack.h:10 [inline]
>  invoke_softirq kernel/softirq.c:228 [inline]
>  __irq_exit_rcu+0x46c/0x510 kernel/softirq.c:422
>  irq_exit+0x14/0x84 kernel/softirq.c:446
>  __handle_domain_irq+0x120/0x1f0 kernel/irq/irqdesc.c:692
>  handle_domain_irq include/linux/irqdesc.h:176 [inline]
>  gic_handle_irq+0x5c/0x1b0 drivers/irqchip/irq-gic.c:370
>  el1_irq+0xb4/0x180 arch/arm64/kernel/entry.S:669
>  arch_local_irq_enable+0xc/0x14 arch/arm64/include/asm/irqflags.h:37
>  default_idle_call+0x64/0xf4 kernel/sched/idle.c:112
>  cpuidle_idle_call kernel/sched/idle.c:194 [inline]
>  do_idle+0x38c/0x4ec kernel/sched/idle.c:300
>  cpu_startup_entry+0x28/0x80 kernel/sched/idle.c:397
>  rest_init+0x1d0/0x2cc init/main.c:721
>  arch_call_rest_init+0x10/0x1c
>  start_kernel+0x3b0/0x3e8 init/main.c:1064
>  0x0
>
>
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[syzbot] upstream boot error: WARNING in vkms_vblank_simulate

2021-03-12 Thread syzbot
Hello,

syzbot found the following issue on:

HEAD commit:f78d76e7 Merge tag 'drm-fixes-2021-03-12-1' of git://anong..
git tree:   upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11c16ba2d0
kernel config:  https://syzkaller.appspot.com/x/.config?x=dc02c6afcb046874
dashboard link: https://syzkaller.appspot.com/bug?extid=333bd014262fd5d0a418
userspace arch: arm

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+333bd014262fd5d0a...@syzkaller.appspotmail.com

[ cut here ]
WARNING: CPU: 0 PID: 0 at drivers/gpu/drm/vkms/vkms_crtc.c:21 
vkms_vblank_simulate+0x26c/0x2f4 drivers/gpu/drm/vkms/vkms_crtc.c:41
Modules linked in:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 
5.12.0-rc2-syzkaller-00338-gf78d76e72a46 #0
Hardware name: linux,dummy-virt (DT)
pstate: 2085 (nzCv daIf -PAN -UAO -TCO BTYPE=--)
pc : vkms_vblank_simulate+0x26c/0x2f4 drivers/gpu/drm/vkms/vkms_crtc.c:21
lr : hrtimer_forward_now include/linux/hrtimer.h:510 [inline]
lr : vkms_vblank_simulate+0x90/0x2f4 drivers/gpu/drm/vkms/vkms_crtc.c:19
sp : 6a693cd0
x29: 6a693cd0 x28: 0c9d1e58 
x27: dfff8000 x26: 6a67f540 
x25: 1fffed4cfeb1 x24: 1fffed4cfeaa 
x23: 0c9d0d30 x22: 00fe4c00 
x21: 6a67f540 x20: 0c9d0e58 
x19: 0c9d1e58 x18: 6a6a1b48 
x17: 1fffe1952345 x16:  
x15: 8000197bf810 x14: 1fffed4d2750 
x13: 0001 x12: 0033 
x11: 12fb4936 x10: 0007 
x9 : 12fb4943 x8 : 800017d14c00 
x7 : f1f1f1f1 x6 : dfff8000 
x5 : 7fff x4 : 0008e44f6b90 
x3 : 0008e54db790 x2 : 0008e44f6b90 
x1 : 0008e54db790 x0 : 0002 
Call trace:
 vkms_vblank_simulate+0x26c/0x2f4 drivers/gpu/drm/vkms/vkms_crtc.c:41
 __run_hrtimer kernel/time/hrtimer.c:1519 [inline]
 __hrtimer_run_queues+0x590/0xe40 kernel/time/hrtimer.c:1583
 hrtimer_interrupt+0x2d4/0x810 kernel/time/hrtimer.c:1645
 timer_handler drivers/clocksource/arm_arch_timer.c:647 [inline]
 arch_timer_handler_phys+0x4c/0x70 drivers/clocksource/arm_arch_timer.c:665
 handle_percpu_devid_irq+0x19c/0x330 kernel/irq/chip.c:930
 generic_handle_irq_desc include/linux/irqdesc.h:158 [inline]
 generic_handle_irq kernel/irq/irqdesc.c:652 [inline]
 __handle_domain_irq+0x11c/0x1f0 kernel/irq/irqdesc.c:689
 handle_domain_irq include/linux/irqdesc.h:176 [inline]
 gic_handle_irq+0x5c/0x1b0 drivers/irqchip/irq-gic.c:370
 el1_irq+0xb4/0x180 arch/arm64/kernel/entry.S:669
 arch_local_irq_restore arch/arm64/include/asm/irqflags.h:124 [inline]
 queue_work_on+0x74/0x110 kernel/workqueue.c:1528
 queue_work include/linux/workqueue.h:507 [inline]
 cursor_timer_handler+0x64/0x100 drivers/video/fbdev/core/fbcon.c:397
 call_timer_fn+0x1d4/0x9c4 kernel/time/timer.c:1431
 expire_timers kernel/time/timer.c:1476 [inline]
 __run_timers.part.0+0x530/0xa00 kernel/time/timer.c:1745
 __run_timers kernel/time/timer.c:1726 [inline]
 run_timer_softirq+0xa4/0x1a0 kernel/time/timer.c:1758
 _stext+0x2b4/0x1084
 do_softirq_own_stack include/asm-generic/softirq_stack.h:10 [inline]
 invoke_softirq kernel/softirq.c:228 [inline]
 __irq_exit_rcu+0x46c/0x510 kernel/softirq.c:422
 irq_exit+0x14/0x84 kernel/softirq.c:446
 __handle_domain_irq+0x120/0x1f0 kernel/irq/irqdesc.c:692
 handle_domain_irq include/linux/irqdesc.h:176 [inline]
 gic_handle_irq+0x5c/0x1b0 drivers/irqchip/irq-gic.c:370
 el1_irq+0xb4/0x180 arch/arm64/kernel/entry.S:669
 arch_local_irq_enable+0xc/0x14 arch/arm64/include/asm/irqflags.h:37
 default_idle_call+0x64/0xf4 kernel/sched/idle.c:112
 cpuidle_idle_call kernel/sched/idle.c:194 [inline]
 do_idle+0x38c/0x4ec kernel/sched/idle.c:300
 cpu_startup_entry+0x28/0x80 kernel/sched/idle.c:397
 rest_init+0x1d0/0x2cc init/main.c:721
 arch_call_rest_init+0x10/0x1c
 start_kernel+0x3b0/0x3e8 init/main.c:1064
 0x0


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkal...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.