diff options
| author | Frederic Weisbecker <frederic@kernel.org> | 2021-02-01 00:05:45 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2021-02-17 14:12:43 +0100 |
| commit | 43789ef3f7d61aa7bed0cb2764e588fc990c30ef (patch) | |
| tree | 016b9a4436405a6e74d362ec2739ab20a578ccf7 /kernel/sched | |
| parent | 54b7429efffc99e845ba9381bee3244f012a06c2 (diff) | |
rcu/nocb: Perform deferred wake up before last idle's need_resched() check
Entering RCU idle mode may cause a deferred wake up of an RCU NOCB_GP
kthread (rcuog) to be serviced.
Usually a local wake up happening while running the idle task is handled
in one of the need_resched() checks carefully placed within the idle
loop that can break to the scheduler.
Unfortunately the call to rcu_idle_enter() is already beyond the last
generic need_resched() check and we may halt the CPU with a resched
request unhandled, leaving the task hanging.
Fix this with splitting the rcuog wakeup handling from rcu_idle_enter()
and place it before the last generic need_resched() check in the idle
loop. It is then assumed that no call to call_rcu() will be performed
after that in the idle loop until the CPU is put in low power mode.
Fixes: 96d3fd0d315a (rcu: Break call_rcu() deadlock involving scheduler and perf)
Reported-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20210131230548.32970-3-frederic@kernel.org
Diffstat (limited to 'kernel/sched')
| -rw-r--r-- | kernel/sched/idle.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c index 305727ea0677..7199e6f23789 100644 --- a/kernel/sched/idle.c +++ b/kernel/sched/idle.c @@ -285,6 +285,7 @@ static void do_idle(void) } arch_cpu_idle_enter(); + rcu_nocb_flush_deferred_wakeup(); /* * In poll mode we reenable interrupts and spin. Also if we |