From: Frederic Weisbecker Date: Mon, 16 Feb 2015 18:20:07 +0000 (+0100) Subject: sched: Fix preempt_schedule_common() triggering tracing recursion X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=06b1f8083d6ed379ec1207a96339f23e8f7abfcf;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git sched: Fix preempt_schedule_common() triggering tracing recursion Since the function graph tracer needs to disable preemption, it might call preempt_schedule() after reenabling it if something triggered the need for rescheduling in between. Therefore we can't trace preempt_schedule() itself because we would face a function tracing recursion otherwise as the tracer is always called before PREEMPT_ACTIVE gets set to prevent that recursion. This is why preempt_schedule() is tagged as "notrace". But the same issue applies to every function called by preempt_schedule() before PREEMPT_ACTIVE is actually set. And preempt_schedule_common() is one such example. Unfortunately we forgot to tag it as notrace as well and as a result we are encountering tracing recursion since it got introduced by: a18b5d0181923 ("sched: Fix missing preemption opportunity") Let's fix that by applying the appropriate function tag to preempt_schedule_common(). Reported-by: Huang Ying Signed-off-by: Frederic Weisbecker Signed-off-by: Peter Zijlstra (Intel) Acked-by: Steven Rostedt Cc: Linus Torvalds Link: http://lkml.kernel.org/r/1424110807-15057-1-git-send-email-fweisbec@gmail.com Signed-off-by: Ingo Molnar --- diff --git a/kernel/sched/core.c b/kernel/sched/core.c index f77acd98f50a..c314000f5e52 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2839,7 +2839,7 @@ void __sched schedule_preempt_disabled(void) preempt_disable(); } -static void preempt_schedule_common(void) +static void __sched notrace preempt_schedule_common(void) { do { __preempt_count_add(PREEMPT_ACTIVE);