From: Steven Rostedt <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org,
linux-rt-users <linux-rt-users@vger.kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Carsten Emde <C.Emde@osadl.org>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
John Kacur <jkacur@redhat.com>,
Paul Gortmaker <paul.gortmaker@windriver.com>,
Julia Cartwright <julia@ni.com>,
Daniel Wagner <daniel.wagner@siemens.com>,
tom.zanussi@linux.intel.com,
Daniel Bristot de Oliveira <bristot@redhat.com>,
Clark Williams <williams@redhat.com>,
Tommaso Cucinotta <tommaso.cucinotta@sssup.it>,
Romulo da Silva de Oliveira <romulo.deoliveira@ufsc.br>,
Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>
Subject: [PATCH RT 19/24] sched/core: Avoid __schedule() being called twice in a row
Date: Fri, 07 Sep 2018 16:59:16 -0400 [thread overview]
Message-ID: <20180907205932.908152135@goodmis.org> (raw)
In-Reply-To: 20180907205857.262840394@goodmis.org
4.14.63-rt41-rc2 stable review patch.
If anyone has any objections, please let me know.
------------------
From: Daniel Bristot de Oliveira <bristot@redhat.com>
[ Upstream commit 2bb94c48b2ffaabf8c15a51e5cc1b4c541988cab ]
If a worker invokes schedule() then we may have the call chain:
schedule()
-> sched_submit_work()
-> wq_worker_sleeping()
-> wake_up_worker()
-> wake_up_process().
The last wakeup may cause a schedule which is unnecessary because we are
already in schedule() and do it anyway.
Add a preempt_disable() + preempt_enable_no_resched() around
wq_worker_sleeping() so the context switch could be delayed until
__schedule().
Signed-off-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: Tommaso Cucinotta <tommaso.cucinotta@sssup.it>
Cc: Romulo da Silva de Oliveira <romulo.deoliveira@ufsc.br>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
[bigeasy: rewrite changelog]
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
kernel/sched/core.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index fa5b76255f8c..a5ce37b90fca 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3482,10 +3482,15 @@ static inline void sched_submit_work(struct task_struct *tsk)
/*
* If a worker went to sleep, notify and ask workqueue whether
* it wants to wake up a task to maintain concurrency.
+ * As this function is called inside the schedule() context,
+ * we disable preemption to avoid it calling schedule() again
+ * in the possible wakeup of a kworker.
*/
- if (tsk->flags & PF_WQ_WORKER)
+ if (tsk->flags & PF_WQ_WORKER) {
+ preempt_disable();
wq_worker_sleeping(tsk);
-
+ preempt_enable_no_resched();
+ }
if (tsk_is_pi_blocked(tsk))
return;
--
2.18.0
next prev parent reply other threads:[~2018-09-07 20:59 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-07 20:58 [PATCH RT 00/24] Linux 4.14.63-rt41-rc2 Steven Rostedt
2018-09-07 20:58 ` [PATCH RT 01/24] sched/fair: Fix CFS bandwidth control lockdep DEADLOCK report Steven Rostedt
2018-09-07 20:58 ` [PATCH RT 02/24] locallock: provide {get,put}_locked_ptr() variants Steven Rostedt
2018-09-07 20:59 ` [PATCH RT 03/24] squashfs: make use of local lock in multi_cpu decompressor Steven Rostedt
2018-09-07 20:59 ` [PATCH RT 04/24] PM / suspend: Prevent might sleep splats (updated) Steven Rostedt
2018-09-07 20:59 ` [PATCH RT 05/24] PM / wakeup: Make events_lock a RAW_SPINLOCK Steven Rostedt
2018-09-07 20:59 ` [PATCH RT 06/24] PM / s2idle: Make s2idle_wait_head swait based Steven Rostedt
2018-09-07 20:59 ` [PATCH RT 07/24] seqlock: provide the same ordering semantics as mainline Steven Rostedt
2018-09-07 20:59 ` [PATCH RT 08/24] Revert "x86: UV: raw_spinlock conversion" Steven Rostedt
2018-09-07 20:59 ` [PATCH RT 09/24] Revert "timer: delay waking softirqs from the jiffy tick" Steven Rostedt
2018-09-07 20:59 ` [PATCH RT 10/24] irqchip/gic-v3-its: Make its_lock a raw_spin_lock_t Steven Rostedt
2018-09-07 20:59 ` [PATCH RT 11/24] sched/migrate_disable: fallback to preempt_disable() instead barrier() Steven Rostedt
2018-09-07 20:59 ` [PATCH RT 12/24] irqchip/gic-v3-its: Move ITS ->pend_page allocation into an early CPU up hook Steven Rostedt
2018-09-07 20:59 ` [PATCH RT 13/24] irqchip/gic-v3-its: Move pending table allocation to init time Steven Rostedt
2018-09-07 20:59 ` [PATCH RT 14/24] x86/ioapic: Dont let setaffinity unmask threaded EOI interrupt too early Steven Rostedt
2018-09-07 20:59 ` [PATCH RT 15/24] efi: Allow efi=runtime Steven Rostedt
2018-09-07 20:59 ` [PATCH RT 16/24] efi: Disable runtime services on RT Steven Rostedt
2018-09-07 20:59 ` [PATCH RT 17/24] crypto: cryptd - add a lock instead preempt_disable/local_bh_disable Steven Rostedt
2018-09-07 20:59 ` [PATCH RT 18/24] crypto: scompress - serialize RT percpu scratch buffer access with a local lock Steven Rostedt
2018-09-07 20:59 ` Steven Rostedt [this message]
2018-09-07 20:59 ` [PATCH RT 20/24] Revert "arm64/xen: Make XEN depend on !RT" Steven Rostedt
2018-09-07 20:59 ` [PATCH RT 21/24] sched: Allow pinned user tasks to be awakened to the CPU they pinned Steven Rostedt
2018-09-07 20:59 ` [PATCH RT 23/24] Revert "softirq: keep the softirq pending check RT-only" Steven Rostedt
2018-09-07 20:59 ` [PATCH RT 24/24] Linux 4.14.63-rt41-rc2 Steven Rostedt
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