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authorPaul E. McKenney <paulmck@kernel.org>2021-02-12 16:20:40 -0800
committerPaul E. McKenney <paulmck@kernel.org>2021-03-15 13:51:48 -0700
commit1c0c4bc1ceb580851b2d76fdef9712b3bdae134b (patch)
tree4d1fc76bbc8f896c9ac8fc24b7aaa87d88d6001b /kernel/softirq.c
parente75956bd00cf4246067c6aee7751faf313233435 (diff)
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>
Diffstat (limited to 'kernel/softirq.c')
-rw-r--r--kernel/softirq.c2
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