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| author | Paul E. McKenney <paulmck@kernel.org> | 2021-02-12 16:20:40 -0800 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2021-03-15 13:51:48 -0700 |
| commit | 1c0c4bc1ceb580851b2d76fdef9712b3bdae134b (patch) | |
| tree | 4d1fc76bbc8f896c9ac8fc24b7aaa87d88d6001b | |
| parent | e75956bd00cf4246067c6aee7751faf313233435 (diff) | |
| download | linux-1c0c4bc1ceb580851b2d76fdef9712b3bdae134b.tar.bz2 | |
softirq: Don't try waking ksoftirqd before it has been spawned
If there is heavy softirq activity, the softirq system will attempt
to awaken ksoftirqd and will stop the traditional back-of-interrupt
softirq processing. This is all well and good, but only if the
ksoftirqd kthreads already exist, which is not the case during early
boot, in which case the system hangs.
One reproducer is as follows:
tools/testing/selftests/rcutorture/bin/kvm.sh --allcpus --duration 2 --configs "TREE03" --kconfig "CONFIG_DEBUG_LOCK_ALLOC=y CONFIG_PROVE_LOCKING=y CONFIG_NO_HZ_IDLE=y CONFIG_HZ_PERIODIC=n" --bootargs "threadirqs=1" --trust-make
This commit therefore adds a couple of existence checks for ksoftirqd
and forces back-of-interrupt softirq processing when ksoftirqd does not
yet exist. With this change, the above test passes.
Reported-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reported-by: Uladzislau Rezki <urezki@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
[ paulmck: Remove unneeded check per Sebastian Siewior feedback. ]
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
| -rw-r--r-- | kernel/softirq.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/softirq.c b/kernel/softirq.c index 9908ec4a9bfe..bad14ca2b520 100644 --- a/kernel/softirq.c +++ b/kernel/softirq.c @@ -211,7 +211,7 @@ static inline void invoke_softirq(void) if (ksoftirqd_running(local_softirq_pending())) return; - if (!force_irqthreads) { + if (!force_irqthreads || !__this_cpu_read(ksoftirqd)) { #ifdef CONFIG_HAVE_IRQ_EXIT_ON_IRQ_STACK /* * We can safely execute softirq on the current stack if |