Message ID | 2fb24ab402d9de45e3cf16e6ba0ad23a7843e5c1.camel@gmx.de (mailing list archive) |
---|---|
State | Handled Elsewhere |
Headers | show |
Series | Re: [PowerPC][Linux-next][6.11.0-rc4-next-20240820] OOPs while running LTP FS Stress | expand |
Hello Mike, Thanks for the patch. I applied your patch and verified the issue, and can confirm your patch fixes the issue. Please add the below tags. Reported-by: Venkat Rao Bagalkote <venkat88@linux.vnet.ibm.com> Tested-by: Venkat Rao Bagalkote <venkat88@linux.vnet.ibm.com> Regards, Venkat. On 19/09/24 11:39 am, Mike Galbraith wrote: > On Mon, 2024-09-16 at 12:00 +0530, Venkat Rao Bagalkote wrote: >> Greetings!!! > Greetings, > >> I am seeing below kernel crash from 6.11.0-rc4-next-20240820. >> >> >> Tried to do git bisect, but it didnt point to right patch. Attached is >> the bisect log. >> >> Any help in fixing this is much appriciated. > I met this, as well as other ways the wheels can fall off that turned > out to have the same root. I gave Peter a heads up with diag offline, > but having now convinced myself that all is well, I'll go ahead and > post a patchlet. > > At the very least it's worth putting out for wider testing.. and should > anyone have something prettier in mind, yeah, do that instead. > > sched: Fix sched_delayed vs cfs_bandwidth > > Meeting an unfinished DELAY_DEQUEUE treated entity in unthrottle_cfs_rq() > leads to a couple terminal scenarios. Finish it first, so ENQUEUE_WAKEUP > can proceed as it would have sans DELAY_DEQUEUE treatment. > > Fixes: 152e11f6df29 ("sched/fair: Implement delayed dequeue") > Signed-off-by: Mike Galbraith <efault@gmx.de> > --- > kernel/sched/fair.c | 10 +++++++--- > 1 file changed, 7 insertions(+), 3 deletions(-) > > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -6049,10 +6049,14 @@ void unthrottle_cfs_rq(struct cfs_rq *cf > for_each_sched_entity(se) { > struct cfs_rq *qcfs_rq = cfs_rq_of(se); > > - if (se->on_rq) { > - SCHED_WARN_ON(se->sched_delayed); > - break; > + /* Handle any unfinished DELAY_DEQUEUE business first. */ > + if (unlikely(se->on_rq && se->sched_delayed)) { > + int flags = DEQUEUE_SLEEP | DEQUEUE_SPECIAL; > + > + dequeue_entity(qcfs_rq, se, flags | DEQUEUE_DELAYED); > } > + if (se->on_rq) > + break; > enqueue_entity(qcfs_rq, se, ENQUEUE_WAKEUP); > > if (cfs_rq_is_idle(group_cfs_rq(se))) > >
On Thu, 2024-09-19 at 20:09 +0530, Venkat Rao Bagalkote wrote: > > Please add the below tags. > > > Reported-by: Venkat Rao Bagalkote <venkat88@linux.vnet.ibm.com> > > Tested-by: Venkat Rao Bagalkote <venkat88@linux.vnet.ibm.com> Sure, and while at it I can brush patchlet's rather scruffy fur. 1. on_rq being implied by sched_delayed, redundant check can go. 2. no tasks anywhere in sight, DEQUEUE_SPECIAL can go. 3. use of unlikely in an unlikely path can also go. No functional change. Too bad everything around there fits in 80 characters, or a couple useless diffstat plus signs could go too. sched: Fix sched_delayed vs cfs_bandwidth Meeting an unfinished DELAY_DEQUEUE treated entity in unthrottle_cfs_rq() leads to a couple terminal scenarios. Finish it first, so ENQUEUE_WAKEUP can proceed as it would have sans DELAY_DEQUEUE treatment. Fixes: 152e11f6df29 ("sched/fair: Implement delayed dequeue") Reported-by: Venkat Rao Bagalkote <venkat88@linux.vnet.ibm.com> Tested-by: Venkat Rao Bagalkote <venkat88@linux.vnet.ibm.com> Signed-off-by: Mike Galbraith <efault@gmx.de> --- kernel/sched/fair.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6049,10 +6049,13 @@ void unthrottle_cfs_rq(struct cfs_rq *cf for_each_sched_entity(se) { struct cfs_rq *qcfs_rq = cfs_rq_of(se); - if (se->on_rq) { - SCHED_WARN_ON(se->sched_delayed); + /* Handle any unfinished DELAY_DEQUEUE business first. */ + if (se->sched_delayed) { + int flags = DEQUEUE_SLEEP | DEQUEUE_DELAYED; + + dequeue_entity(qcfs_rq, se, flags); + } else if (se->on_rq) break; - } enqueue_entity(qcfs_rq, se, ENQUEUE_WAKEUP); if (cfs_rq_is_idle(group_cfs_rq(se)))
--- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6049,10 +6049,14 @@ void unthrottle_cfs_rq(struct cfs_rq *cf for_each_sched_entity(se) { struct cfs_rq *qcfs_rq = cfs_rq_of(se); - if (se->on_rq) { - SCHED_WARN_ON(se->sched_delayed); - break; + /* Handle any unfinished DELAY_DEQUEUE business first. */ + if (unlikely(se->on_rq && se->sched_delayed)) { + int flags = DEQUEUE_SLEEP | DEQUEUE_SPECIAL; + + dequeue_entity(qcfs_rq, se, flags | DEQUEUE_DELAYED); } + if (se->on_rq) + break; enqueue_entity(qcfs_rq, se, ENQUEUE_WAKEUP); if (cfs_rq_is_idle(group_cfs_rq(se)))