Re: svn commit: r350005 - head/sys/kern
On 7/31/19 12:42 PM, Konstantin Belousov wrote: > On Wed, Jul 31, 2019 at 10:08:39AM -0700, Bryan Drewery wrote: >> On 7/30/19 10:14 PM, Konstantin Belousov wrote: >>> No, you should create a situation where the python process ends the endless >>> loop, as reported. Then, it should become killable by 9 with the first >>> chunk only applied. >>> >> >> I don't have an easy way to test that. kill -9 inside the loop didn't >> work. Once the loop ended the process was done; it is very short lived >> and the calling code is buried in Python I think. > With only the umtxq_check_susp() chunk applied, you would wait for > python to start looping, then verify that kill -9 works. > > Anyway, I believe that the change is correct, and put the review at > https://reviews.freebsd.org/D21124. I will commit after it get some > sanity checking by mentioned people. > Right. I did that earlier and it did not work. I can try again shortly. -- Regards, Bryan Drewery signature.asc Description: OpenPGP digital signature
Re: svn commit: r350005 - head/sys/kern
On Wed, Jul 31, 2019 at 10:08:39AM -0700, Bryan Drewery wrote: > On 7/30/19 10:14 PM, Konstantin Belousov wrote: > > No, you should create a situation where the python process ends the endless > > loop, as reported. Then, it should become killable by 9 with the first > > chunk only applied. > > > > I don't have an easy way to test that. kill -9 inside the loop didn't > work. Once the loop ended the process was done; it is very short lived > and the calling code is buried in Python I think. With only the umtxq_check_susp() chunk applied, you would wait for python to start looping, then verify that kill -9 works. Anyway, I believe that the change is correct, and put the review at https://reviews.freebsd.org/D21124. I will commit after it get some sanity checking by mentioned people. ___ svn-src-all@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
Re: svn commit: r350005 - head/sys/kern
On 7/30/19 10:14 PM, Konstantin Belousov wrote: > On Tue, Jul 30, 2019 at 08:40:28PM -0700, Bryan Drewery wrote: >> This 2nd change alone (&& count1 == 0) was sufficient to fix the endless >> loop problem. > Good, thank you. > >> >> I am not sure how to test the umtxq_check_susp() change. Do I just need >> to ptrace the process? > > No, you should create a situation where the python process ends the endless > loop, as reported. Then, it should become killable by 9 with the first > chunk only applied. > I don't have an easy way to test that. kill -9 inside the loop didn't work. Once the loop ended the process was done; it is very short lived and the calling code is buried in Python I think. -- Regards, Bryan Drewery signature.asc Description: OpenPGP digital signature
Re: svn commit: r350005 - head/sys/kern
On Tue, Jul 30, 2019 at 08:40:28PM -0700, Bryan Drewery wrote: > This 2nd change alone (&& count1 == 0) was sufficient to fix the endless > loop problem. Good, thank you. > > I am not sure how to test the umtxq_check_susp() change. Do I just need > to ptrace the process? No, you should create a situation where the python process ends the endless loop, as reported. Then, it should become killable by 9 with the first chunk only applied. ___ svn-src-all@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
Re: svn commit: r350005 - head/sys/kern
On 7/30/19 4:27 PM, Konstantin Belousov wrote:
> On Wed, Jul 31, 2019 at 02:13:02AM +0300, Konstantin Belousov wrote:
>> On Tue, Jul 30, 2019 at 03:04:57PM -0700, Bryan Drewery wrote:
>>> On 7/15/2019 12:18 PM, Konstantin Belousov wrote:
Author: kib
Date: Mon Jul 15 19:18:25 2019
New Revision: 350005
URL: https://svnweb.freebsd.org/changeset/base/350005
Log:
In do_sem2_wait(), balance umtx_key_get() with umtx_key_release() on
retry.
>>>
>>> Is this also needed in do_sem_wait()? A similar pattern seems to be there.
>> No, I do not think do_sem_wait() has similar issue, because the again label
>> does not re-get the key.
>>
>>>
>>> I ask because of what I referenced on IRC. I have some processes stuck
>>> in here from a 10.4 jail.
>>>
~/git/poudriere # procstat -kk 1498
PIDTID COMMTDNAME KSTACK
1498 100710 python2.7 - mi_switch+0x174
sleepq_switch+0x110 sleepq_catch_signals+0x417 sleepq_wait_sig+0xf
_sleep+0x2d0 umtxq_sleep+0x153 do_sem_wait+0x42c __umtx_op_sem_wait+0x6e
amd64_syscall+0x2bb fast_syscall_common+0x101
1498 101575 python2.7 - mi_switch+0x174
sleepq_switch+0x110 sleepq_catch_signals+0x417 sleepq_wait_sig+0xf
_sleep+0x2d0 umtxq_sleep+0x153 do_sem_wait+0x42c __umtx_op_sem_wait+0x6e
amd64_syscall+0x2bb fast_syscall_common+0x101
1498 101657 python2.7 -
>>> ...
~/git/poudriere # procstat -kk 1498
PIDTID COMMTDNAME KSTACK
1498 100710 python2.7 - mi_switch+0x174
sleepq_switch+0x110 sleepq_catch_signals+0x417 sleepq_wait_sig+0xf
_sleep+0x2d0 umtxq_sleep+0x153 do_sem_wait+0x42c __umtx_op_sem_wait+0x6e
amd64_syscall+0x2bb fast_syscall_common+0x101
1498 101575 python2.7 - mi_switch+0x174
sleepq_switch+0x110 sleepq_catch_signals+0x417 sleepq_wait_sig+0xf
_sleep+0x2d0 umtxq_sleep+0x153 do_sem_wait+0x42c __umtx_op_sem_wait+0x6e
amd64_syscall+0x2bb fast_syscall_common+0x101
1498 101657 python2.7 - do_sem_wait+0x1b6
__umtx_op_sem_wait+0x6e amd64_syscall+0x2bb fast_syscall_common+0x101
>>> ...
~/git/poudriere # procstat -kk 94392
PIDTID COMMTDNAME KSTACK
94392 101815 python2.7 - mi_switch+0x174
sleepq_switch+0x110 sleepq_catch_signals+0x417 sleepq_wait_sig+0xf
_sleep+0x2d0 umtxq_sleep+0x153 do_sem_wait+0x42c __umtx_op_sem_wait+0x6e
amd64_syscall+0x2bb fast_syscall_common+0x101
94392 101816 python2.7 -
__mtx_lock_sleep+0x118 __mtx_lock_flags+0x102 _sleep+0x334 umtxq_busy+0xb7
do_sem_wait+0x161 __umtx_op_sem_wait+0x6e amd64_syscall+0x2bb
fast_syscall_common+0x101
94392 102076 python2.7 - __mtx_lock_flags+0x94
do_sem_wait+0x228 __umtx_op_sem_wait+0x6e amd64_syscall+0x2bb
fast_syscall_common+0x101
>>
>> Try this. We should only retry casueword if it failed spuriously.
>>
>> diff --git a/sys/kern/kern_umtx.c b/sys/kern/kern_umtx.c
>> index bb998457975..6c914ab6f3e 100644
>> --- a/sys/kern/kern_umtx.c
>> +++ b/sys/kern/kern_umtx.c
>> @@ -3229,7 +3229,8 @@ do_sem_wait(struct thread *td, struct _usem *sem,
>> struct _umtx_time *timeout)
>> rv = casueword32(>_has_waiters, 0, , 1);
>> if (rv == 0)
>> rv1 = fueword32(>_count, );
>> -if (rv == -1 || (rv == 0 && (rv1 == -1 || count != 0)) || rv == 1) {
>> +if (rv == -1 || (rv == 0 && (rv1 == -1 || count != 0)) ||
>> +(rv == 1 && count1 == 0)) {
>> umtxq_lock(>uq_key);
>> umtxq_unbusy(>uq_key);
>> umtxq_remove(uq);
>
> I think there is another problem, since even despite our intent of looping
> just because of casueword returned 1, the umtxq_check_susp() should have
> terminated the loop. I believe the following update would fix that.
>
> If you have time, can you please apply only the umtxq_check_susp() chunk
> and see if it helps as well ? [Both chunks are needed for correctness, but
> the umtxq_check_susp() is almost impossible to test in combination]
>
> diff --git a/sys/kern/kern_umtx.c b/sys/kern/kern_umtx.c
> index bb998457975..08bdd1a1a9a 100644
> --- a/sys/kern/kern_umtx.c
> +++ b/sys/kern/kern_umtx.c
> @@ -723,13 +723,11 @@ umtxq_check_susp(struct thread *td, bool sleep)
> error = 0;
> p = td->td_proc;
> PROC_LOCK(p);
> - if (P_SHOULDSTOP(p) ||
> - ((p->p_flag & P_TRACED) && (td->td_dbgflags & TDB_SUSPEND))) {
> - if (p->p_flag & P_SINGLE_EXIT)
> - error = EINTR;
> - else
> - error = sleep ? thread_suspend_check(0) : ERESTART;
> - }
> + if (p->p_flag & P_SINGLE_EXIT)
> +
Re: svn commit: r350005 - head/sys/kern
On 7/30/2019 4:27 PM, Konstantin Belousov wrote:
> On Wed, Jul 31, 2019 at 02:13:02AM +0300, Konstantin Belousov wrote:
>> On Tue, Jul 30, 2019 at 03:04:57PM -0700, Bryan Drewery wrote:
>>> On 7/15/2019 12:18 PM, Konstantin Belousov wrote:
Author: kib
Date: Mon Jul 15 19:18:25 2019
New Revision: 350005
URL: https://svnweb.freebsd.org/changeset/base/350005
Log:
In do_sem2_wait(), balance umtx_key_get() with umtx_key_release() on
retry.
>>>
>>> Is this also needed in do_sem_wait()? A similar pattern seems to be there.
>> No, I do not think do_sem_wait() has similar issue, because the again label
>> does not re-get the key.
>>
>>>
>>> I ask because of what I referenced on IRC. I have some processes stuck
>>> in here from a 10.4 jail.
>>>
~/git/poudriere # procstat -kk 1498
PIDTID COMMTDNAME KSTACK
1498 100710 python2.7 - mi_switch+0x174
sleepq_switch+0x110 sleepq_catch_signals+0x417 sleepq_wait_sig+0xf
_sleep+0x2d0 umtxq_sleep+0x153 do_sem_wait+0x42c __umtx_op_sem_wait+0x6e
amd64_syscall+0x2bb fast_syscall_common+0x101
1498 101575 python2.7 - mi_switch+0x174
sleepq_switch+0x110 sleepq_catch_signals+0x417 sleepq_wait_sig+0xf
_sleep+0x2d0 umtxq_sleep+0x153 do_sem_wait+0x42c __umtx_op_sem_wait+0x6e
amd64_syscall+0x2bb fast_syscall_common+0x101
1498 101657 python2.7 -
>>> ...
~/git/poudriere # procstat -kk 1498
PIDTID COMMTDNAME KSTACK
1498 100710 python2.7 - mi_switch+0x174
sleepq_switch+0x110 sleepq_catch_signals+0x417 sleepq_wait_sig+0xf
_sleep+0x2d0 umtxq_sleep+0x153 do_sem_wait+0x42c __umtx_op_sem_wait+0x6e
amd64_syscall+0x2bb fast_syscall_common+0x101
1498 101575 python2.7 - mi_switch+0x174
sleepq_switch+0x110 sleepq_catch_signals+0x417 sleepq_wait_sig+0xf
_sleep+0x2d0 umtxq_sleep+0x153 do_sem_wait+0x42c __umtx_op_sem_wait+0x6e
amd64_syscall+0x2bb fast_syscall_common+0x101
1498 101657 python2.7 - do_sem_wait+0x1b6
__umtx_op_sem_wait+0x6e amd64_syscall+0x2bb fast_syscall_common+0x101
>>> ...
~/git/poudriere # procstat -kk 94392
PIDTID COMMTDNAME KSTACK
94392 101815 python2.7 - mi_switch+0x174
sleepq_switch+0x110 sleepq_catch_signals+0x417 sleepq_wait_sig+0xf
_sleep+0x2d0 umtxq_sleep+0x153 do_sem_wait+0x42c __umtx_op_sem_wait+0x6e
amd64_syscall+0x2bb fast_syscall_common+0x101
94392 101816 python2.7 -
__mtx_lock_sleep+0x118 __mtx_lock_flags+0x102 _sleep+0x334 umtxq_busy+0xb7
do_sem_wait+0x161 __umtx_op_sem_wait+0x6e amd64_syscall+0x2bb
fast_syscall_common+0x101
94392 102076 python2.7 - __mtx_lock_flags+0x94
do_sem_wait+0x228 __umtx_op_sem_wait+0x6e amd64_syscall+0x2bb
fast_syscall_common+0x101
>>
>> Try this. We should only retry casueword if it failed spuriously.
>>
>> diff --git a/sys/kern/kern_umtx.c b/sys/kern/kern_umtx.c
>> index bb998457975..6c914ab6f3e 100644
>> --- a/sys/kern/kern_umtx.c
>> +++ b/sys/kern/kern_umtx.c
>> @@ -3229,7 +3229,8 @@ do_sem_wait(struct thread *td, struct _usem *sem,
>> struct _umtx_time *timeout)
>> rv = casueword32(>_has_waiters, 0, , 1);
>> if (rv == 0)
>> rv1 = fueword32(>_count, );
>> -if (rv == -1 || (rv == 0 && (rv1 == -1 || count != 0)) || rv == 1) {
>> +if (rv == -1 || (rv == 0 && (rv1 == -1 || count != 0)) ||
>> +(rv == 1 && count1 == 0)) {
>> umtxq_lock(>uq_key);
>> umtxq_unbusy(>uq_key);
>> umtxq_remove(uq);
>
> I think there is another problem, since even despite our intent of looping
> just because of casueword returned 1, the umtxq_check_susp() should have
> terminated the loop. I believe the following update would fix that.
>
> If you have time, can you please apply only the umtxq_check_susp() chunk
> and see if it helps as well ? [Both chunks are needed for correctness, but
> the umtxq_check_susp() is almost impossible to test in combination]
What is the expected "working" test for the umtxq_check_susp() change? I
get the 100% CPU and kill -9 does not kill it.
> ~ # procstat -kk 19150
> PIDTID COMMTDNAME KSTACK
> 19150 101524 python2.7 - do_sem_wait+0x150
> __umtx_op_sem_wait+0x6e amd64_syscall+0x2bb fast_syscall_common+0x101
> 19150 101553 python2.7 - mi_switch+0x174
> sleepq_switch+0x110 sleepq_catch_signals+0x417 sleepq_wait_sig+0xf
> _sleep+0x2d0 umtxq_sleep+0x153 do_sem_wait+0x41c __umtx_op_sem_wait+0x6e
> amd64_syscall+0x2bb fast_syscall_common+0x101
> 19150 101554 python2.7
Re: svn commit: r350005 - head/sys/kern
On Wed, Jul 31, 2019 at 02:13:02AM +0300, Konstantin Belousov wrote:
> On Tue, Jul 30, 2019 at 03:04:57PM -0700, Bryan Drewery wrote:
> > On 7/15/2019 12:18 PM, Konstantin Belousov wrote:
> > > Author: kib
> > > Date: Mon Jul 15 19:18:25 2019
> > > New Revision: 350005
> > > URL: https://svnweb.freebsd.org/changeset/base/350005
> > >
> > > Log:
> > > In do_sem2_wait(), balance umtx_key_get() with umtx_key_release() on
> > > retry.
> > >
> >
> > Is this also needed in do_sem_wait()? A similar pattern seems to be there.
> No, I do not think do_sem_wait() has similar issue, because the again label
> does not re-get the key.
>
> >
> > I ask because of what I referenced on IRC. I have some processes stuck
> > in here from a 10.4 jail.
> >
> > > ~/git/poudriere # procstat -kk 1498
> > > PIDTID COMMTDNAME KSTACK
> > > 1498 100710 python2.7 - mi_switch+0x174
> > > sleepq_switch+0x110 sleepq_catch_signals+0x417 sleepq_wait_sig+0xf
> > > _sleep+0x2d0 umtxq_sleep+0x153 do_sem_wait+0x42c __umtx_op_sem_wait+0x6e
> > > amd64_syscall+0x2bb fast_syscall_common+0x101
> > > 1498 101575 python2.7 - mi_switch+0x174
> > > sleepq_switch+0x110 sleepq_catch_signals+0x417 sleepq_wait_sig+0xf
> > > _sleep+0x2d0 umtxq_sleep+0x153 do_sem_wait+0x42c __umtx_op_sem_wait+0x6e
> > > amd64_syscall+0x2bb fast_syscall_common+0x101
> > > 1498 101657 python2.7 -
> > ...
> > > ~/git/poudriere # procstat -kk 1498
> > > PIDTID COMMTDNAME KSTACK
> > > 1498 100710 python2.7 - mi_switch+0x174
> > > sleepq_switch+0x110 sleepq_catch_signals+0x417 sleepq_wait_sig+0xf
> > > _sleep+0x2d0 umtxq_sleep+0x153 do_sem_wait+0x42c __umtx_op_sem_wait+0x6e
> > > amd64_syscall+0x2bb fast_syscall_common+0x101
> > > 1498 101575 python2.7 - mi_switch+0x174
> > > sleepq_switch+0x110 sleepq_catch_signals+0x417 sleepq_wait_sig+0xf
> > > _sleep+0x2d0 umtxq_sleep+0x153 do_sem_wait+0x42c __umtx_op_sem_wait+0x6e
> > > amd64_syscall+0x2bb fast_syscall_common+0x101
> > > 1498 101657 python2.7 - do_sem_wait+0x1b6
> > > __umtx_op_sem_wait+0x6e amd64_syscall+0x2bb fast_syscall_common+0x101
> > ...
> > > ~/git/poudriere # procstat -kk 94392
> > > PIDTID COMMTDNAME KSTACK
> > > 94392 101815 python2.7 - mi_switch+0x174
> > > sleepq_switch+0x110 sleepq_catch_signals+0x417 sleepq_wait_sig+0xf
> > > _sleep+0x2d0 umtxq_sleep+0x153 do_sem_wait+0x42c __umtx_op_sem_wait+0x6e
> > > amd64_syscall+0x2bb fast_syscall_common+0x101
> > > 94392 101816 python2.7 -
> > > __mtx_lock_sleep+0x118 __mtx_lock_flags+0x102 _sleep+0x334
> > > umtxq_busy+0xb7 do_sem_wait+0x161 __umtx_op_sem_wait+0x6e
> > > amd64_syscall+0x2bb fast_syscall_common+0x101
> > > 94392 102076 python2.7 -
> > > __mtx_lock_flags+0x94 do_sem_wait+0x228 __umtx_op_sem_wait+0x6e
> > > amd64_syscall+0x2bb fast_syscall_common+0x101
>
> Try this. We should only retry casueword if it failed spuriously.
>
> diff --git a/sys/kern/kern_umtx.c b/sys/kern/kern_umtx.c
> index bb998457975..6c914ab6f3e 100644
> --- a/sys/kern/kern_umtx.c
> +++ b/sys/kern/kern_umtx.c
> @@ -3229,7 +3229,8 @@ do_sem_wait(struct thread *td, struct _usem *sem,
> struct _umtx_time *timeout)
> rv = casueword32(>_has_waiters, 0, , 1);
> if (rv == 0)
> rv1 = fueword32(>_count, );
> - if (rv == -1 || (rv == 0 && (rv1 == -1 || count != 0)) || rv == 1) {
> + if (rv == -1 || (rv == 0 && (rv1 == -1 || count != 0)) ||
> + (rv == 1 && count1 == 0)) {
> umtxq_lock(>uq_key);
> umtxq_unbusy(>uq_key);
> umtxq_remove(uq);
I think there is another problem, since even despite our intent of looping
just because of casueword returned 1, the umtxq_check_susp() should have
terminated the loop. I believe the following update would fix that.
If you have time, can you please apply only the umtxq_check_susp() chunk
and see if it helps as well ? [Both chunks are needed for correctness, but
the umtxq_check_susp() is almost impossible to test in combination]
diff --git a/sys/kern/kern_umtx.c b/sys/kern/kern_umtx.c
index bb998457975..08bdd1a1a9a 100644
--- a/sys/kern/kern_umtx.c
+++ b/sys/kern/kern_umtx.c
@@ -723,13 +723,11 @@ umtxq_check_susp(struct thread *td, bool sleep)
error = 0;
p = td->td_proc;
PROC_LOCK(p);
- if (P_SHOULDSTOP(p) ||
- ((p->p_flag & P_TRACED) && (td->td_dbgflags & TDB_SUSPEND))) {
- if (p->p_flag & P_SINGLE_EXIT)
- error = EINTR;
- else
- error = sleep ? thread_suspend_check(0) : ERESTART;
- }
+ if (p->p_flag & P_SINGLE_EXIT)
+ error = EINTR;
+ else if
Re: svn commit: r350005 - head/sys/kern
On Tue, Jul 30, 2019 at 03:04:57PM -0700, Bryan Drewery wrote:
> On 7/15/2019 12:18 PM, Konstantin Belousov wrote:
> > Author: kib
> > Date: Mon Jul 15 19:18:25 2019
> > New Revision: 350005
> > URL: https://svnweb.freebsd.org/changeset/base/350005
> >
> > Log:
> > In do_sem2_wait(), balance umtx_key_get() with umtx_key_release() on
> > retry.
> >
>
> Is this also needed in do_sem_wait()? A similar pattern seems to be there.
No, I do not think do_sem_wait() has similar issue, because the again label
does not re-get the key.
>
> I ask because of what I referenced on IRC. I have some processes stuck
> in here from a 10.4 jail.
>
> > ~/git/poudriere # procstat -kk 1498
> > PIDTID COMMTDNAME KSTACK
> > 1498 100710 python2.7 - mi_switch+0x174
> > sleepq_switch+0x110 sleepq_catch_signals+0x417 sleepq_wait_sig+0xf
> > _sleep+0x2d0 umtxq_sleep+0x153 do_sem_wait+0x42c __umtx_op_sem_wait+0x6e
> > amd64_syscall+0x2bb fast_syscall_common+0x101
> > 1498 101575 python2.7 - mi_switch+0x174
> > sleepq_switch+0x110 sleepq_catch_signals+0x417 sleepq_wait_sig+0xf
> > _sleep+0x2d0 umtxq_sleep+0x153 do_sem_wait+0x42c __umtx_op_sem_wait+0x6e
> > amd64_syscall+0x2bb fast_syscall_common+0x101
> > 1498 101657 python2.7 -
> ...
> > ~/git/poudriere # procstat -kk 1498
> > PIDTID COMMTDNAME KSTACK
> > 1498 100710 python2.7 - mi_switch+0x174
> > sleepq_switch+0x110 sleepq_catch_signals+0x417 sleepq_wait_sig+0xf
> > _sleep+0x2d0 umtxq_sleep+0x153 do_sem_wait+0x42c __umtx_op_sem_wait+0x6e
> > amd64_syscall+0x2bb fast_syscall_common+0x101
> > 1498 101575 python2.7 - mi_switch+0x174
> > sleepq_switch+0x110 sleepq_catch_signals+0x417 sleepq_wait_sig+0xf
> > _sleep+0x2d0 umtxq_sleep+0x153 do_sem_wait+0x42c __umtx_op_sem_wait+0x6e
> > amd64_syscall+0x2bb fast_syscall_common+0x101
> > 1498 101657 python2.7 - do_sem_wait+0x1b6
> > __umtx_op_sem_wait+0x6e amd64_syscall+0x2bb fast_syscall_common+0x101
> ...
> > ~/git/poudriere # procstat -kk 94392
> > PIDTID COMMTDNAME KSTACK
> > 94392 101815 python2.7 - mi_switch+0x174
> > sleepq_switch+0x110 sleepq_catch_signals+0x417 sleepq_wait_sig+0xf
> > _sleep+0x2d0 umtxq_sleep+0x153 do_sem_wait+0x42c __umtx_op_sem_wait+0x6e
> > amd64_syscall+0x2bb fast_syscall_common+0x101
> > 94392 101816 python2.7 - __mtx_lock_sleep+0x118
> > __mtx_lock_flags+0x102 _sleep+0x334 umtxq_busy+0xb7 do_sem_wait+0x161
> > __umtx_op_sem_wait+0x6e amd64_syscall+0x2bb fast_syscall_common+0x101
> > 94392 102076 python2.7 - __mtx_lock_flags+0x94
> > do_sem_wait+0x228 __umtx_op_sem_wait+0x6e amd64_syscall+0x2bb
> > fast_syscall_common+0x101
Try this. We should only retry casueword if it failed spuriously.
diff --git a/sys/kern/kern_umtx.c b/sys/kern/kern_umtx.c
index bb998457975..6c914ab6f3e 100644
--- a/sys/kern/kern_umtx.c
+++ b/sys/kern/kern_umtx.c
@@ -3229,7 +3229,8 @@ do_sem_wait(struct thread *td, struct _usem *sem, struct
_umtx_time *timeout)
rv = casueword32(>_has_waiters, 0, , 1);
if (rv == 0)
rv1 = fueword32(>_count, );
- if (rv == -1 || (rv == 0 && (rv1 == -1 || count != 0)) || rv == 1) {
+ if (rv == -1 || (rv == 0 && (rv1 == -1 || count != 0)) ||
+ (rv == 1 && count1 == 0)) {
umtxq_lock(>uq_key);
umtxq_unbusy(>uq_key);
umtxq_remove(uq);
___
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Re: svn commit: r350005 - head/sys/kern
On 7/15/2019 12:18 PM, Konstantin Belousov wrote: > Author: kib > Date: Mon Jul 15 19:18:25 2019 > New Revision: 350005 > URL: https://svnweb.freebsd.org/changeset/base/350005 > > Log: > In do_sem2_wait(), balance umtx_key_get() with umtx_key_release() on retry. > Is this also needed in do_sem_wait()? A similar pattern seems to be there. I ask because of what I referenced on IRC. I have some processes stuck in here from a 10.4 jail. > ~/git/poudriere # procstat -kk 1498 > PIDTID COMMTDNAME KSTACK > 1498 100710 python2.7 - mi_switch+0x174 > sleepq_switch+0x110 sleepq_catch_signals+0x417 sleepq_wait_sig+0xf > _sleep+0x2d0 umtxq_sleep+0x153 do_sem_wait+0x42c __umtx_op_sem_wait+0x6e > amd64_syscall+0x2bb fast_syscall_common+0x101 > 1498 101575 python2.7 - mi_switch+0x174 > sleepq_switch+0x110 sleepq_catch_signals+0x417 sleepq_wait_sig+0xf > _sleep+0x2d0 umtxq_sleep+0x153 do_sem_wait+0x42c __umtx_op_sem_wait+0x6e > amd64_syscall+0x2bb fast_syscall_common+0x101 > 1498 101657 python2.7 - ... > ~/git/poudriere # procstat -kk 1498 > PIDTID COMMTDNAME KSTACK > 1498 100710 python2.7 - mi_switch+0x174 > sleepq_switch+0x110 sleepq_catch_signals+0x417 sleepq_wait_sig+0xf > _sleep+0x2d0 umtxq_sleep+0x153 do_sem_wait+0x42c __umtx_op_sem_wait+0x6e > amd64_syscall+0x2bb fast_syscall_common+0x101 > 1498 101575 python2.7 - mi_switch+0x174 > sleepq_switch+0x110 sleepq_catch_signals+0x417 sleepq_wait_sig+0xf > _sleep+0x2d0 umtxq_sleep+0x153 do_sem_wait+0x42c __umtx_op_sem_wait+0x6e > amd64_syscall+0x2bb fast_syscall_common+0x101 > 1498 101657 python2.7 - do_sem_wait+0x1b6 > __umtx_op_sem_wait+0x6e amd64_syscall+0x2bb fast_syscall_common+0x101 ... > ~/git/poudriere # procstat -kk 94392 > PIDTID COMMTDNAME KSTACK > 94392 101815 python2.7 - mi_switch+0x174 > sleepq_switch+0x110 sleepq_catch_signals+0x417 sleepq_wait_sig+0xf > _sleep+0x2d0 umtxq_sleep+0x153 do_sem_wait+0x42c __umtx_op_sem_wait+0x6e > amd64_syscall+0x2bb fast_syscall_common+0x101 > 94392 101816 python2.7 - __mtx_lock_sleep+0x118 > __mtx_lock_flags+0x102 _sleep+0x334 umtxq_busy+0xb7 do_sem_wait+0x161 > __umtx_op_sem_wait+0x6e amd64_syscall+0x2bb fast_syscall_common+0x101 > 94392 102076 python2.7 - __mtx_lock_flags+0x94 > do_sem_wait+0x228 __umtx_op_sem_wait+0x6e amd64_syscall+0x2bb > fast_syscall_common+0x101 > Reported by:ler > Bisected and reviewed by: markj > Sponsored by: The FreeBSD Foundation > MFC after: 12 days > > Modified: > head/sys/kern/kern_umtx.c > > Modified: head/sys/kern/kern_umtx.c > == > --- head/sys/kern/kern_umtx.c Mon Jul 15 17:13:32 2019(r350004) > +++ head/sys/kern/kern_umtx.c Mon Jul 15 19:18:25 2019(r350005) > @@ -3316,14 +3316,13 @@ do_sem2_wait(struct thread *td, struct _usem2 *sem, st > > uq = td->td_umtxq; > flags = fuword32(>_flags); > - error = umtx_key_get(sem, TYPE_SEM, GET_SHARE(flags), >uq_key); > - if (error != 0) > - return (error); > - > if (timeout != NULL) > abs_timeout_init2(, timeout); > > again: > + error = umtx_key_get(sem, TYPE_SEM, GET_SHARE(flags), >uq_key); > + if (error != 0) > + return (error); > umtxq_lock(>uq_key); > umtxq_busy(>uq_key); > umtxq_insert(uq); > -- Regards, Bryan Drewery signature.asc Description: OpenPGP digital signature
