From: Peter Zijlstra peterz@infradead.org
commit 19dbdcb8039cff16669a05136a29180778d16d0a upstream.
It's clearly documented that smp function calls cannot be invoked from softirq handling context. Unfortunately nothing enforces that or emits a warning.
A single function call can be invoked from softirq context only via smp_call_function_single_async().
The only legit context is task context, so add a warning to that effect.
Reported-by: luferry luferry@163.com Signed-off-by: Peter Zijlstra peterz@infradead.org Signed-off-by: Thomas Gleixner tglx@linutronix.de Link: https://lkml.kernel.org/r/20190718160601.GP3402@hirez.programming.kicks-ass.... Cc: stable stable@vger.kernel.org # 4.19.x Signed-off-by: Wen Yang simon.wy@alibaba-inc.com --- kernel/smp.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+)
diff --git a/kernel/smp.c b/kernel/smp.c index 084c8b3..9afcbb4 100644 --- a/kernel/smp.c +++ b/kernel/smp.c @@ -290,6 +290,14 @@ int smp_call_function_single(int cpu, smp_call_func_t func, void *info, WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled() && !oops_in_progress);
+ /* + * When @wait we can deadlock when we interrupt between llist_add() and + * arch_send_call_function_ipi*(); when !@wait we can deadlock due to + * csd_lock() on because the interrupt context uses the same csd + * storage. + */ + WARN_ON_ONCE(!in_task()); + csd = &csd_stack; if (!wait) { csd = this_cpu_ptr(&csd_data); @@ -415,6 +423,14 @@ void smp_call_function_many(const struct cpumask *mask, WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled() && !oops_in_progress && !early_boot_irqs_disabled);
+ /* + * When @wait we can deadlock when we interrupt between llist_add() and + * arch_send_call_function_ipi*(); when !@wait we can deadlock due to + * csd_lock() on because the interrupt context uses the same csd + * storage. + */ + WARN_ON_ONCE(!in_task()); + /* Try to fastpath. So, what's a CPU they want? Ignoring this one. */ cpu = cpumask_first_and(mask, cpu_online_mask); if (cpu == this_cpu)