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| author |   Peter Zijlstra <peterz@infradead.org> | 2020-11-16 13:10:12 +0100 |
|---|---|---|
| committer |   Paul E. McKenney <paulmck@kernel.org> | 2020-11-19 19:34:17 -0800 |
| commit | 6dbce04d8417ae706596366e16841d77c454ba52 (patch) | |
| tree | f4f34a632bbf504557cb50c2412d80225f8b0576 /kernel/rcu | |
| parent | rcu: Don't invoke try_invoke_on_locked_down_task() with irqs disabled (diff) | |
| download | linux-dev-6dbce04d8417ae706596366e16841d77c454ba52.tar.xz linux-dev-6dbce04d8417ae706596366e16841d77c454ba52.zip | |
rcu: Allow rcu_irq_enter_check_tick() from NMI
Eugenio managed to tickle #PF from NMI context which resulted in
hitting a WARN in RCU through irqentry_enter() ->
__rcu_irq_enter_check_tick().
However, this situation is perfectly sane and does not warrant an
WARN. The #PF will (necessarily) be atomic and not require messing
with the tick state, so early return is correct. This commit
therefore removes the WARN.
Fixes: aaf2bc50df1f ("rcu: Abstract out rcu_irq_enter_check_tick() from rcu_nmi_enter()")
Reported-by: "Eugenio Pérez" <eupm90@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to 'kernel/rcu')
| -rw-r--r-- | kernel/rcu/tree.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 06895ef85d69..93e1808ac3fc 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -928,8 +928,8 @@ void __rcu_irq_enter_check_tick(void) { struct rcu_data *rdp = this_cpu_ptr(&rcu_data); - // Enabling the tick is unsafe in NMI handlers. - if (WARN_ON_ONCE(in_nmi())) + // If we're here from NMI there's nothing to do. + if (in_nmi()) return; RCU_LOCKDEP_WARN(rcu_dynticks_curr_cpu_in_eqs(), |