From: Peter Zijlstra <peterz@xxxxxxxxxxxxx> 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@xxxxxxx> Signed-off-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Link: https://lkml.kernel.org/r/20190718160601.GP3402@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx Cc: stable <stable@xxxxxxxxxxxxxxx> # 4.9.x Signed-off-by: Wen Yang <simon.wy@xxxxxxxxxxxxxxx> --- kernel/smp.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/kernel/smp.c b/kernel/smp.c index 399905f..f2b29c4 100644 --- a/kernel/smp.c +++ b/kernel/smp.c @@ -276,6 +276,14 @@ 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); @@ -401,6 +409,14 @@ 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) -- 1.8.3.1
