From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: linux-kernel@vger.kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>,
Peter Zijlstra <peterz@infradead.org>,
Steven Rostedt <rostedt@goodmis.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Matthew Wilcox <willy@infradead.org>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Subject: [PATCH v2 7/8] flex_proportions: Disable preemption entering the write section.
Date: Thu, 25 Aug 2022 18:41:30 +0200 [thread overview]
Message-ID: <20220825164131.402717-8-bigeasy@linutronix.de> (raw)
In-Reply-To: <20220825164131.402717-1-bigeasy@linutronix.de>
The seqcount fprop_global::sequence is not associated with a lock. The
write section (fprop_new_period()) is invoked from a timer and since the
softirq is preemptible on PREEMPT_RT it is possible to preempt the write
section which is not desited.
Disable preemption around the write section on PREEMPT_RT.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
lib/flex_proportions.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/lib/flex_proportions.c b/lib/flex_proportions.c
index 05cccbcf1661a..83332fefa6f42 100644
--- a/lib/flex_proportions.c
+++ b/lib/flex_proportions.c
@@ -70,6 +70,7 @@ bool fprop_new_period(struct fprop_global *p, int periods)
*/
if (events <= 1)
return false;
+ preempt_disable_nested();
write_seqcount_begin(&p->sequence);
if (periods < 64)
events -= events >> periods;
@@ -77,6 +78,7 @@ bool fprop_new_period(struct fprop_global *p, int periods)
percpu_counter_add(&p->events, -events);
p->period += periods;
write_seqcount_end(&p->sequence);
+ preempt_enable_nested();
return true;
}
--
2.37.2
next prev parent reply other threads:[~2022-08-25 16:42 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-25 16:41 [PATCH v2 0/8] Replace PREEMPT_RT ifdefs with preempt_[dis|en]able_nested() Sebastian Andrzej Siewior
2022-08-25 16:41 ` [PATCH v2 1/8] preempt: Provide preempt_[dis|en]able_nested() Sebastian Andrzej Siewior
2022-09-19 12:37 ` [tip: sched/rt] " tip-bot2 for Thomas Gleixner
2022-08-25 16:41 ` [PATCH v2 2/8] dentry: Use preempt_[dis|en]able_nested() Sebastian Andrzej Siewior
2022-08-26 7:52 ` Christian Brauner
2022-09-19 12:37 ` [tip: sched/rt] " tip-bot2 for Thomas Gleixner
2022-08-25 16:41 ` [PATCH v2 3/8] mm/vmstat: " Sebastian Andrzej Siewior
2022-09-01 14:41 ` Michal Hocko
2022-09-19 12:37 ` [tip: sched/rt] " tip-bot2 for Thomas Gleixner
2022-08-25 16:41 ` [PATCH v2 4/8] mm/debug: Provide VM_WARN_ON_IRQS_ENABLED() Sebastian Andrzej Siewior
2022-09-01 14:41 ` Michal Hocko
2022-09-19 12:37 ` [tip: sched/rt] " tip-bot2 for Thomas Gleixner
2022-08-25 16:41 ` [PATCH v2 5/8] mm/memcontrol: Replace the PREEMPT_RT conditionals Sebastian Andrzej Siewior
2022-09-01 14:45 ` Michal Hocko
2022-09-19 12:37 ` [tip: sched/rt] " tip-bot2 for Thomas Gleixner
2022-08-25 16:41 ` [PATCH v2 6/8] mm/compaction: Get rid of RT ifdeffery Sebastian Andrzej Siewior
2022-09-19 12:37 ` [tip: sched/rt] " tip-bot2 for Thomas Gleixner
2022-08-25 16:41 ` Sebastian Andrzej Siewior [this message]
2022-09-19 12:37 ` [tip: sched/rt] flex_proportions: Disable preemption entering the write section tip-bot2 for Sebastian Andrzej Siewior
2022-08-25 16:41 ` [PATCH v2 8/8] u64_stats: Streamline the implementation Sebastian Andrzej Siewior
2022-09-19 12:37 ` [tip: sched/rt] " tip-bot2 for Thomas Gleixner
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