* [PATCH resend] sched/smt: fix unbalance sched_smt_present dec/inc
@ 2024-07-02 8:11 Yang Yingliang
2024-07-02 8:44 ` Peter Zijlstra
0 siblings, 1 reply; 3+ messages in thread
From: Yang Yingliang @ 2024-07-02 8:11 UTC (permalink / raw)
To: linux-kernel
Cc: mingo, peterz, juri.lelli, vincent.guittot, dietmar.eggemann,
rostedt, bsegall, mgorman, bristot, vschneid, tglx, yu.c.chen,
tim.c.chen, yangyingliang, liwei391
From: Yang Yingliang <yangyingliang@huawei.com>
I got the following warn report while doing stress test:
jump label: negative count!
WARNING: CPU: 3 PID: 38 at kernel/jump_label.c:263 static_key_slow_try_dec+0x9d/0xb0
Call Trace:
<TASK>
__static_key_slow_dec_cpuslocked+0x16/0x70
sched_cpu_deactivate+0x26e/0x2a0
cpuhp_invoke_callback+0x3ad/0x10d0
cpuhp_thread_fun+0x3f5/0x680
smpboot_thread_fn+0x56d/0x8d0
kthread+0x309/0x400
ret_from_fork+0x41/0x70
ret_from_fork_asm+0x1b/0x30
</TASK>
Because when cpuset_cpu_inactive() fails in sched_cpu_deactivate(),
the cpu offline failed, but sched_smt_present is decremented before
calling sched_cpu_deactivate(), it leads to unbalanced dec/inc, so
fix it by incrementing sched_smt_present in the error path.
Fixes: c5511d03ec09 ("sched/smt: Make sched_smt_present track topology")
Reviewed-by: Chen Yu <yu.c.chen@intel.com>
Reviewed-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
---
kernel/sched/core.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index bcf2c4cc0522..5ab6717b57e0 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -9756,6 +9756,10 @@ int sched_cpu_deactivate(unsigned int cpu)
sched_update_numa(cpu, false);
ret = cpuset_cpu_inactive(cpu);
if (ret) {
+#ifdef CONFIG_SCHED_SMT
+ if (cpumask_weight(cpu_smt_mask(cpu)) == 2)
+ static_branch_inc_cpuslocked(&sched_smt_present);
+#endif
balance_push_set(cpu, false);
set_cpu_active(cpu, true);
sched_update_numa(cpu, true);
--
2.25.1
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH resend] sched/smt: fix unbalance sched_smt_present dec/inc
2024-07-02 8:11 [PATCH resend] sched/smt: fix unbalance sched_smt_present dec/inc Yang Yingliang
@ 2024-07-02 8:44 ` Peter Zijlstra
2024-07-02 11:38 ` yangyingliang
0 siblings, 1 reply; 3+ messages in thread
From: Peter Zijlstra @ 2024-07-02 8:44 UTC (permalink / raw)
To: Yang Yingliang
Cc: linux-kernel, mingo, juri.lelli, vincent.guittot,
dietmar.eggemann, rostedt, bsegall, mgorman, bristot, vschneid,
tglx, yu.c.chen, tim.c.chen, yangyingliang, liwei391
On Tue, Jul 02, 2024 at 04:11:28PM +0800, Yang Yingliang wrote:
> From: Yang Yingliang <yangyingliang@huawei.com>
>
> I got the following warn report while doing stress test:
>
> jump label: negative count!
> WARNING: CPU: 3 PID: 38 at kernel/jump_label.c:263 static_key_slow_try_dec+0x9d/0xb0
> Call Trace:
> <TASK>
> __static_key_slow_dec_cpuslocked+0x16/0x70
> sched_cpu_deactivate+0x26e/0x2a0
> cpuhp_invoke_callback+0x3ad/0x10d0
> cpuhp_thread_fun+0x3f5/0x680
> smpboot_thread_fn+0x56d/0x8d0
> kthread+0x309/0x400
> ret_from_fork+0x41/0x70
> ret_from_fork_asm+0x1b/0x30
> </TASK>
>
> Because when cpuset_cpu_inactive() fails in sched_cpu_deactivate(),
> the cpu offline failed, but sched_smt_present is decremented before
> calling sched_cpu_deactivate(), it leads to unbalanced dec/inc, so
> fix it by incrementing sched_smt_present in the error path.
>
> Fixes: c5511d03ec09 ("sched/smt: Make sched_smt_present track topology")
> Reviewed-by: Chen Yu <yu.c.chen@intel.com>
> Reviewed-by: Tim Chen <tim.c.chen@linux.intel.com>
> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
> ---
> kernel/sched/core.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index bcf2c4cc0522..5ab6717b57e0 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -9756,6 +9756,10 @@ int sched_cpu_deactivate(unsigned int cpu)
> sched_update_numa(cpu, false);
> ret = cpuset_cpu_inactive(cpu);
> if (ret) {
> +#ifdef CONFIG_SCHED_SMT
> + if (cpumask_weight(cpu_smt_mask(cpu)) == 2)
> + static_branch_inc_cpuslocked(&sched_smt_present);
> +#endif
> balance_push_set(cpu, false);
> set_cpu_active(cpu, true);
> sched_update_numa(cpu, true);
Yes, does indeed appear needed, however!, when I look at
what else goes before this failure, should we not also call
set_rq_online() and things like that?
That is, can we rework things to be less fragile by sharing code between
this error path and sched_cpu_activate() ?
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH resend] sched/smt: fix unbalance sched_smt_present dec/inc
2024-07-02 8:44 ` Peter Zijlstra
@ 2024-07-02 11:38 ` yangyingliang
0 siblings, 0 replies; 3+ messages in thread
From: yangyingliang @ 2024-07-02 11:38 UTC (permalink / raw)
To: Peter Zijlstra
Cc: linux-kernel, mingo, juri.lelli, vincent.guittot,
dietmar.eggemann, rostedt, bsegall, mgorman, bristot, vschneid,
tglx, yu.c.chen, tim.c.chen, yangyingliang, liwei391
> -----Original Messages-----
> From: "Peter Zijlstra" <peterz@infradead.org>
> Sent Time: 2024-07-02 16:44:18 (Tuesday)
> To: "Yang Yingliang" <yangyingliang@huaweicloud.com>
> Cc: linux-kernel@vger.kernel.org, mingo@redhat.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, vschneid@redhat.com, tglx@linutronix.de, yu.c.chen@intel.com, tim.c.chen@linux.intel.com, yangyingliang@huawei.com, liwei391@huawei.com
> Subject: Re: [PATCH resend] sched/smt: fix unbalance sched_smt_present dec/inc
>
> On Tue, Jul 02, 2024 at 04:11:28PM +0800, Yang Yingliang wrote:
> > From: Yang Yingliang <yangyingliang@huawei.com>
> >
> > I got the following warn report while doing stress test:
> >
> > jump label: negative count!
> > WARNING: CPU: 3 PID: 38 at kernel/jump_label.c:263 static_key_slow_try_dec+0x9d/0xb0
> > Call Trace:
> > <task>
> > __static_key_slow_dec_cpuslocked+0x16/0x70
> > sched_cpu_deactivate+0x26e/0x2a0
> > cpuhp_invoke_callback+0x3ad/0x10d0
> > cpuhp_thread_fun+0x3f5/0x680
> > smpboot_thread_fn+0x56d/0x8d0
> > kthread+0x309/0x400
> > ret_from_fork+0x41/0x70
> > ret_from_fork_asm+0x1b/0x30
> > </task>
> >
> > Because when cpuset_cpu_inactive() fails in sched_cpu_deactivate(),
> > the cpu offline failed, but sched_smt_present is decremented before
> > calling sched_cpu_deactivate(), it leads to unbalanced dec/inc, so
> > fix it by incrementing sched_smt_present in the error path.
> >
> > Fixes: c5511d03ec09 ("sched/smt: Make sched_smt_present track topology")
> > Reviewed-by: Chen Yu <yu.c.chen@intel.com>
> > Reviewed-by: Tim Chen <tim.c.chen@linux.intel.com>
> > Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
> > ---
> > kernel/sched/core.c | 4 ++++
> > 1 file changed, 4 insertions(+)
> >
> > diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> > index bcf2c4cc0522..5ab6717b57e0 100644
> > --- a/kernel/sched/core.c
> > +++ b/kernel/sched/core.c
> > @@ -9756,6 +9756,10 @@ int sched_cpu_deactivate(unsigned int cpu)
> > sched_update_numa(cpu, false);
> > ret = cpuset_cpu_inactive(cpu);
> > if (ret) {
> > +#ifdef CONFIG_SCHED_SMT
> > + if (cpumask_weight(cpu_smt_mask(cpu)) == 2)
> > + static_branch_inc_cpuslocked(&sched_smt_present);
> > +#endif
> > balance_push_set(cpu, false);
> > set_cpu_active(cpu, true);
> > sched_update_numa(cpu, true);
>
> Yes, does indeed appear needed, however!, when I look at
> what else goes before this failure, should we not also call
> set_rq_online() and things like that?
Yes, set_rq_online() is needed in the error path. I will send a new patch to add this.
>
> That is, can we rework things to be less fragile by sharing code between
> this error path and sched_cpu_activate() ?
</yangyingliang@huawei.com></tim.c.chen@linux.intel.com></yu.c.chen@intel.com></yangyingliang@huawei.com></yangyingliang@huaweicloud.com></peterz@infradead.org>
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2024-07-02 11:38 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2024-07-02 8:11 [PATCH resend] sched/smt: fix unbalance sched_smt_present dec/inc Yang Yingliang
2024-07-02 8:44 ` Peter Zijlstra
2024-07-02 11:38 ` yangyingliang
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
all inboxes | Powered by JetHome®