Messages in this thread Patch in this message | | | Date | Fri, 06 Aug 2021 12:57:51 -0000 | From | "tip-bot2 for Dietmar Eggemann" <> | Subject | [tip: sched/core] sched/deadline: Fix missing clock update in migrate_task_rq_dl() |
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The following commit has been merged into the sched/core branch of tip:
Commit-ID: b4da13aa28d4fd0071247b7b41c579ee8a86c81a Gitweb: https://git.kernel.org/tip/b4da13aa28d4fd0071247b7b41c579ee8a86c81a Author: Dietmar Eggemann <dietmar.eggemann@arm.com> AuthorDate: Wed, 04 Aug 2021 15:59:25 +02:00 Committer: Peter Zijlstra <peterz@infradead.org> CommitterDate: Fri, 06 Aug 2021 14:25:24 +02:00
sched/deadline: Fix missing clock update in migrate_task_rq_dl()
A missing clock update is causing the following warning:
rq->clock_update_flags < RQCF_ACT_SKIP WARNING: CPU: 112 PID: 2041 at kernel/sched/sched.h:1453 sub_running_bw.isra.0+0x190/0x1a0 ... CPU: 112 PID: 2041 Comm: sugov:112 Tainted: G W 5.14.0-rc1 #1 Hardware name: WIWYNN Mt.Jade Server System B81.030Z1.0007/Mt.Jade Motherboard, BIOS 1.6.20210526 (SCP: 1.06.20210526) 2021/05/26 ... Call trace: sub_running_bw.isra.0+0x190/0x1a0 migrate_task_rq_dl+0xf8/0x1e0 set_task_cpu+0xa8/0x1f0 try_to_wake_up+0x150/0x3d4 wake_up_q+0x64/0xc0 __up_write+0xd0/0x1c0 up_write+0x4c/0x2b0 cppc_set_perf+0x120/0x2d0 cppc_cpufreq_set_target+0xe0/0x1a4 [cppc_cpufreq] __cpufreq_driver_target+0x74/0x140 sugov_work+0x64/0x80 kthread_worker_fn+0xe0/0x230 kthread+0x138/0x140 ret_from_fork+0x10/0x18
The task causing this is the `cppc_fie` DL task introduced by commit 1eb5dde674f5 ("cpufreq: CPPC: Add support for frequency invariance").
With CONFIG_ACPI_CPPC_CPUFREQ_FIE=y and schedutil cpufreq governor on slow-switching system (like on this Ampere Altra WIWYNN Mt. Jade Arm Server):
DL task `curr=sugov:112` lets `p=cppc_fie` migrate and since the latter is in `non_contending` state, migrate_task_rq_dl() calls
sub_running_bw()->__sub_running_bw()->cpufreq_update_util()-> rq_clock()->assert_clock_updated()
on p.
Fix this by updating the clock for a non_contending task in migrate_task_rq_dl() before calling sub_running_bw().
Reported-by: Bruno Goncalves <bgoncalv@redhat.com> Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Daniel Bristot de Oliveira <bristot@kernel.org> Acked-by: Juri Lelli <juri.lelli@redhat.com> Link: https://lore.kernel.org/r/20210804135925.3734605-1-dietmar.eggemann@arm.com --- kernel/sched/deadline.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index 5cafc64..e943146 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -1733,6 +1733,7 @@ static void migrate_task_rq_dl(struct task_struct *p, int new_cpu __maybe_unused */ raw_spin_rq_lock(rq); if (p->dl.dl_non_contending) { + update_rq_clock(rq); sub_running_bw(&p->dl, &rq->dl); p->dl.dl_non_contending = 0; /*
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