From e73dfe30930b75c98746152e7a2f6a8ab6067b51 Mon Sep 17 00:00:00 2001 From: Zhen Lei Date: Thu, 4 Aug 2022 10:34:19 +0800 Subject: sched/debug: Try trigger_single_cpu_backtrace(cpu) in dump_cpu_task() The trigger_all_cpu_backtrace() function attempts to send an NMI to the target CPU, which usually provides much better stack traces than the dump_cpu_task() function's approach of dumping that stack from some other CPU. So much so that most calls to dump_cpu_task() only happen after a call to trigger_all_cpu_backtrace() has failed. And the exception to this rule really should attempt to use trigger_all_cpu_backtrace() first. Therefore, move the trigger_all_cpu_backtrace() invocation into dump_cpu_task(). Signed-off-by: Zhen Lei Signed-off-by: Paul E. McKenney Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Juri Lelli Cc: Vincent Guittot Cc: Dietmar Eggemann Cc: Ben Segall Cc: Mel Gorman Cc: Daniel Bristot de Oliveira Cc: Valentin Schneider --- kernel/smp.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) (limited to 'kernel/smp.c') diff --git a/kernel/smp.c b/kernel/smp.c index 650810a6f29b..e8cdc025a046 100644 --- a/kernel/smp.c +++ b/kernel/smp.c @@ -370,8 +370,7 @@ static bool csd_lock_wait_toolong(struct __call_single_data *csd, u64 ts0, u64 * if (cpu >= 0) { if (static_branch_unlikely(&csdlock_debug_extended)) csd_lock_print_extended(csd, cpu); - if (!trigger_single_cpu_backtrace(cpu)) - dump_cpu_task(cpu); + dump_cpu_task(cpu); if (!cpu_cur_csd) { pr_alert("csd: Re-sending CSD lock (#%d) IPI from CPU#%02d to CPU#%02d\n", *bug_id, raw_smp_processor_id(), cpu); arch_send_call_function_single_ipi(cpu); -- cgit v1.2.3-59-g8ed1b