From: Paul E. McKenney Date: Mon, 30 Jan 2012 16:46:32 +0000 (-0800) Subject: lockdep: Add CPU-idle/offline warning to lockdep-RCU splat X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=c5fdcec927ee31fc96e92339c3a83ac6e0725289;p=linux-beck.git lockdep: Add CPU-idle/offline warning to lockdep-RCU splat It is illegal to use RCU from a CPU that has reported idleness or offlinedness to RCU. However, it can be quite difficult to determine from a stack trace whether or not a given CPU is idle or offline. Therefore, this commit adds idle/offline diagnostics to the lockdep-RCU error message. Signed-off-by: Paul E. McKenney Signed-off-by: Paul E. McKenney --- diff --git a/kernel/lockdep.c b/kernel/lockdep.c index 8889f7dd7c46..ea9ee4518c35 100644 --- a/kernel/lockdep.c +++ b/kernel/lockdep.c @@ -4176,7 +4176,13 @@ void lockdep_rcu_suspicious(const char *file, const int line, const char *s) printk("-------------------------------\n"); printk("%s:%d %s!\n", file, line, s); printk("\nother info that might help us debug this:\n\n"); - printk("\nrcu_scheduler_active = %d, debug_locks = %d\n", rcu_scheduler_active, debug_locks); + printk("\n%srcu_scheduler_active = %d, debug_locks = %d\n", + !rcu_lockdep_current_cpu_online() + ? "RCU used illegally from offline CPU!\n" + : rcu_is_cpu_idle() + ? "RCU used illegally from idle CPU!\n" + : "", + rcu_scheduler_active, debug_locks); /* * If a CPU is in the RCU-free window in idle (ie: in the section