Re: [PATCH PREEMPT RT] rt-mutex: fix deadlock in device mapper

On Thu, 2017-11-23 at 15:42 +0100, Sebastian Siewior wrote: > On 2017-11-21 22:20:51 [+0100], Mike Galbraith wrote: > > On Tue, 2017-11-21 at 14:56 -0500, Mikulas Patocka wrote: > > > > > > If we don't have any reason why it is needed to unplug block requests > > > when > > > a spinlock is

Re: [PATCH PREEMPT RT] rt-mutex: fix deadlock in device mapper

On Thu, 2017-11-23 at 15:42 +0100, Sebastian Siewior wrote: > On 2017-11-21 22:20:51 [+0100], Mike Galbraith wrote: > > On Tue, 2017-11-21 at 14:56 -0500, Mikulas Patocka wrote: > > > > > > If we don't have any reason why it is needed to unplug block requests > > > when > > > a spinlock is

Re: [PATCH PREEMPT RT] rt-mutex: fix deadlock in device mapper

On 2017-11-21 22:20:51 [+0100], Mike Galbraith wrote: > On Tue, 2017-11-21 at 14:56 -0500, Mikulas Patocka wrote: > > > > If we don't have any reason why it is needed to unplug block requests when > > a spinlock is taken - so let's not do this. > > That's perfectly fine.  I guess I shouldn't

Re: [PATCH PREEMPT RT] rt-mutex: fix deadlock in device mapper

On 2017-11-21 22:20:51 [+0100], Mike Galbraith wrote: > On Tue, 2017-11-21 at 14:56 -0500, Mikulas Patocka wrote: > > > > If we don't have any reason why it is needed to unplug block requests when > > a spinlock is taken - so let's not do this. > > That's perfectly fine.  I guess I shouldn't

Re: [PATCH PREEMPT RT] rt-mutex: fix deadlock in device mapper

On Tue, 2017-11-21 at 14:56 -0500, Mikulas Patocka wrote: > > If we don't have any reason why it is needed to unplug block requests when > a spinlock is taken - so let's not do this. That's perfectly fine.  I guess I shouldn't have even mentioned having encountered unplug at mutex being

Re: [PATCH PREEMPT RT] rt-mutex: fix deadlock in device mapper

On Tue, 2017-11-21 at 14:56 -0500, Mikulas Patocka wrote: > > If we don't have any reason why it is needed to unplug block requests when > a spinlock is taken - so let's not do this. That's perfectly fine.  I guess I shouldn't have even mentioned having encountered unplug at mutex being

Re: [PATCH PREEMPT RT] rt-mutex: fix deadlock in device mapper

On Tue, 21 Nov 2017, Mike Galbraith wrote: > On Tue, 2017-11-21 at 11:11 -0500, Mikulas Patocka wrote: > > > > So, drop the spinlock unplugging and leave only mutex unplugging, > > reproduce the deadlock and send the stacktraces. > > Nah, I reproduced it five years ago.  Is any of that

Re: [PATCH PREEMPT RT] rt-mutex: fix deadlock in device mapper

On Tue, 21 Nov 2017, Mike Galbraith wrote: > On Tue, 2017-11-21 at 11:11 -0500, Mikulas Patocka wrote: > > > > So, drop the spinlock unplugging and leave only mutex unplugging, > > reproduce the deadlock and send the stacktraces. > > Nah, I reproduced it five years ago.  Is any of that

Re: [PATCH PREEMPT RT] rt-mutex: fix deadlock in device mapper

On Tue, 2017-11-21 at 11:11 -0500, Mikulas Patocka wrote: > > So, drop the spinlock unplugging and leave only mutex unplugging, > reproduce the deadlock and send the stacktraces. Nah, I reproduced it five years ago.  Is any of that relevant today?  Damned if I know.  Your report was the first

Re: [PATCH PREEMPT RT] rt-mutex: fix deadlock in device mapper

On Tue, 2017-11-21 at 11:11 -0500, Mikulas Patocka wrote: > > So, drop the spinlock unplugging and leave only mutex unplugging, > reproduce the deadlock and send the stacktraces. Nah, I reproduced it five years ago.  Is any of that relevant today?  Damned if I know.  Your report was the first

Re: [PATCH PREEMPT RT] rt-mutex: fix deadlock in device mapper

On Tue, 21 Nov 2017, Mike Galbraith wrote: > On Tue, 2017-11-21 at 09:37 +0100, Thomas Gleixner wrote: > > On Tue, 21 Nov 2017, Mike Galbraith wrote: > > > On Mon, 2017-11-20 at 16:33 -0500, Mikulas Patocka wrote: > > > > > > > > Is there some specific scenario where you need to call > > > >

Re: [PATCH PREEMPT RT] rt-mutex: fix deadlock in device mapper

On Tue, 21 Nov 2017, Mike Galbraith wrote: > On Tue, 2017-11-21 at 09:37 +0100, Thomas Gleixner wrote: > > On Tue, 21 Nov 2017, Mike Galbraith wrote: > > > On Mon, 2017-11-20 at 16:33 -0500, Mikulas Patocka wrote: > > > > > > > > Is there some specific scenario where you need to call > > > >

Re: [PATCH PREEMPT RT] rt-mutex: fix deadlock in device mapper

On Tue, 2017-11-21 at 09:37 +0100, Thomas Gleixner wrote: > On Tue, 21 Nov 2017, Mike Galbraith wrote: > > On Mon, 2017-11-20 at 16:33 -0500, Mikulas Patocka wrote: > > > > > > Is there some specific scenario where you need to call > > > blk_schedule_flush_plug from rt_spin_lock_fastlock? > > >

Re: [PATCH PREEMPT RT] rt-mutex: fix deadlock in device mapper

On Tue, 2017-11-21 at 09:37 +0100, Thomas Gleixner wrote: > On Tue, 21 Nov 2017, Mike Galbraith wrote: > > On Mon, 2017-11-20 at 16:33 -0500, Mikulas Patocka wrote: > > > > > > Is there some specific scenario where you need to call > > > blk_schedule_flush_plug from rt_spin_lock_fastlock? > > >

Re: [PATCH PREEMPT RT] rt-mutex: fix deadlock in device mapper

On Tue, 21 Nov 2017, Mike Galbraith wrote: > On Mon, 2017-11-20 at 16:33 -0500, Mikulas Patocka wrote: > > > > Is there some specific scenario where you need to call > > blk_schedule_flush_plug from rt_spin_lock_fastlock? > > Excellent question.  What's the difference between not getting IO >

Re: [PATCH PREEMPT RT] rt-mutex: fix deadlock in device mapper

On Tue, 21 Nov 2017, Mike Galbraith wrote: > On Mon, 2017-11-20 at 16:33 -0500, Mikulas Patocka wrote: > > > > Is there some specific scenario where you need to call > > blk_schedule_flush_plug from rt_spin_lock_fastlock? > > Excellent question.  What's the difference between not getting IO >

Re: [PATCH PREEMPT RT] rt-mutex: fix deadlock in device mapper

On Mon, 2017-11-20 at 16:33 -0500, Mikulas Patocka wrote: > > Is there some specific scenario where you need to call > blk_schedule_flush_plug from rt_spin_lock_fastlock? Excellent question.  What's the difference between not getting IO started because you meet a mutex with an rt_mutex under

Re: [PATCH PREEMPT RT] rt-mutex: fix deadlock in device mapper

On Mon, 2017-11-20 at 16:33 -0500, Mikulas Patocka wrote: > > Is there some specific scenario where you need to call > blk_schedule_flush_plug from rt_spin_lock_fastlock? Excellent question.  What's the difference between not getting IO started because you meet a mutex with an rt_mutex under

Re: [PATCH PREEMPT RT] rt-mutex: fix deadlock in device mapper

On Mon, 20 Nov 2017, Mikulas Patocka wrote: > > > On Mon, 20 Nov 2017, Sebastian Siewior wrote: > > > On 2017-11-18 19:37:10 [+0100], Mike Galbraith wrote: > > > Below is my 2012 3.0-rt version of that for reference; at that time we > > > were using slab, and slab_lock referenced below was a

Re: [PATCH PREEMPT RT] rt-mutex: fix deadlock in device mapper

On Mon, 20 Nov 2017, Mikulas Patocka wrote: > > > On Mon, 20 Nov 2017, Sebastian Siewior wrote: > > > On 2017-11-18 19:37:10 [+0100], Mike Galbraith wrote: > > > Below is my 2012 3.0-rt version of that for reference; at that time we > > > were using slab, and slab_lock referenced below was a

Re: [PATCH PREEMPT RT] rt-mutex: fix deadlock in device mapper

On Sat, 18 Nov 2017, Mike Galbraith wrote: > On Fri, 2017-11-17 at 15:57 +0100, Sebastian Siewior wrote: > > On 2017-11-13 12:56:53 [-0500], Mikulas Patocka wrote: > > > Hi > > Hi, > > > > > I'm submitting this patch for the CONFIG_PREEMPT_RT patch. It fixes > > > deadlocks in device mapper

Re: [PATCH PREEMPT RT] rt-mutex: fix deadlock in device mapper

On Sat, 18 Nov 2017, Mike Galbraith wrote: > On Fri, 2017-11-17 at 15:57 +0100, Sebastian Siewior wrote: > > On 2017-11-13 12:56:53 [-0500], Mikulas Patocka wrote: > > > Hi > > Hi, > > > > > I'm submitting this patch for the CONFIG_PREEMPT_RT patch. It fixes > > > deadlocks in device mapper

Re: [PATCH PREEMPT RT] rt-mutex: fix deadlock in device mapper

On Mon, 20 Nov 2017, Sebastian Siewior wrote: > On 2017-11-18 19:37:10 [+0100], Mike Galbraith wrote: > > Below is my 2012 3.0-rt version of that for reference; at that time we > > were using slab, and slab_lock referenced below was a local_lock.  The > > comment came from crash analysis of a

Re: [PATCH PREEMPT RT] rt-mutex: fix deadlock in device mapper

On Mon, 20 Nov 2017, Sebastian Siewior wrote: > On 2017-11-18 19:37:10 [+0100], Mike Galbraith wrote: > > Below is my 2012 3.0-rt version of that for reference; at that time we > > were using slab, and slab_lock referenced below was a local_lock.  The > > comment came from crash analysis of a

Re: [PATCH PREEMPT RT] rt-mutex: fix deadlock in device mapper

On Mon, 2017-11-20 at 13:43 +0100, Mike Galbraith wrote: > The problem was converted spinlocks (and added RT locks). But I suppose lockdep should gripe about that these days...

Re: [PATCH PREEMPT RT] rt-mutex: fix deadlock in device mapper

On Mon, 2017-11-20 at 13:43 +0100, Mike Galbraith wrote: > The problem was converted spinlocks (and added RT locks). But I suppose lockdep should gripe about that these days...

Re: [PATCH PREEMPT RT] rt-mutex: fix deadlock in device mapper

On Mon, 2017-11-20 at 11:53 +0100, Sebastian Siewior wrote: > > To your question whether or not delaying IO can cause any deadlocks is > something that I can't answer and this something that would affect !RT, > too. I tried to add lockdep to bit-spinlocks but this does not work > because one

Re: [PATCH PREEMPT RT] rt-mutex: fix deadlock in device mapper

On Mon, 2017-11-20 at 11:53 +0100, Sebastian Siewior wrote: > > To your question whether or not delaying IO can cause any deadlocks is > something that I can't answer and this something that would affect !RT, > too. I tried to add lockdep to bit-spinlocks but this does not work > because one

Re: [PATCH PREEMPT RT] rt-mutex: fix deadlock in device mapper

On 2017-11-18 19:37:10 [+0100], Mike Galbraith wrote: > Below is my 2012 3.0-rt version of that for reference; at that time we > were using slab, and slab_lock referenced below was a local_lock.  The > comment came from crash analysis of a deadlock I met before adding the > (yeah, hacky)

Re: [PATCH PREEMPT RT] rt-mutex: fix deadlock in device mapper

On 2017-11-18 19:37:10 [+0100], Mike Galbraith wrote: > Below is my 2012 3.0-rt version of that for reference; at that time we > were using slab, and slab_lock referenced below was a local_lock.  The > comment came from crash analysis of a deadlock I met before adding the > (yeah, hacky)

Re: [PATCH PREEMPT RT] rt-mutex: fix deadlock in device mapper

On Fri, 2017-11-17 at 15:57 +0100, Sebastian Siewior wrote: > On 2017-11-13 12:56:53 [-0500], Mikulas Patocka wrote: > > Hi > Hi, > > > I'm submitting this patch for the CONFIG_PREEMPT_RT patch. It fixes > > deadlocks in device mapper when real time preemption is used. > > applied, thank you.

Re: [PATCH PREEMPT RT] rt-mutex: fix deadlock in device mapper

On Fri, 2017-11-17 at 15:57 +0100, Sebastian Siewior wrote: > On 2017-11-13 12:56:53 [-0500], Mikulas Patocka wrote: > > Hi > Hi, > > > I'm submitting this patch for the CONFIG_PREEMPT_RT patch. It fixes > > deadlocks in device mapper when real time preemption is used. > > applied, thank you.

Re: [PATCH PREEMPT RT] rt-mutex: fix deadlock in device mapper

On 2017-11-13 12:56:53 [-0500], Mikulas Patocka wrote: > Hi Hi, > I'm submitting this patch for the CONFIG_PREEMPT_RT patch. It fixes > deadlocks in device mapper when real time preemption is used. applied, thank you. > Mikulas Sebastian

Re: [PATCH PREEMPT RT] rt-mutex: fix deadlock in device mapper

On 2017-11-13 12:56:53 [-0500], Mikulas Patocka wrote: > Hi Hi, > I'm submitting this patch for the CONFIG_PREEMPT_RT patch. It fixes > deadlocks in device mapper when real time preemption is used. applied, thank you. > Mikulas Sebastian

Re: [PATCH PREEMPT RT] rt-mutex: fix deadlock in device mapper

On Tue, 14 Nov 2017, Sebastian Siewior wrote: > [ minimize CC ] > > On 2017-11-13 12:56:53 [-0500], Mikulas Patocka wrote: > > Hi > > > > I'm submitting this patch for the CONFIG_PREEMPT_RT patch. It fixes > > deadlocks in device mapper when real time preemption is used. > > I run into a

Re: [PATCH PREEMPT RT] rt-mutex: fix deadlock in device mapper

On Tue, 14 Nov 2017, Sebastian Siewior wrote: > [ minimize CC ] > > On 2017-11-13 12:56:53 [-0500], Mikulas Patocka wrote: > > Hi > > > > I'm submitting this patch for the CONFIG_PREEMPT_RT patch. It fixes > > deadlocks in device mapper when real time preemption is used. > > I run into a

[PATCH PREEMPT RT] rt-mutex: fix deadlock in device mapper

Hi I'm submitting this patch for the CONFIG_PREEMPT_RT patch. It fixes deadlocks in device mapper when real time preemption is used. Mikulas From: Mikulas Patocka When some block device driver creates a bio and submits it to another block device driver, the bio is

[PATCH PREEMPT RT] rt-mutex: fix deadlock in device mapper

Hi I'm submitting this patch for the CONFIG_PREEMPT_RT patch. It fixes deadlocks in device mapper when real time preemption is used. Mikulas From: Mikulas Patocka When some block device driver creates a bio and submits it to another block device driver, the bio is added to