From: Paul E. McKenney Date: Tue, 10 Jan 2012 22:23:29 +0000 (-0800) Subject: rcu: Check for callback invocation from offline CPUs X-Git-Tag: Ubuntu-goldfish-3.4.0-4.27~744^2^2~33 X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=8146c4e2e2c1972216afece5c50e072e86120e42;hp=778d250a29224795e6320b58928bafa6b6104a06;p=mirror_ubuntu-zesty-kernel.git rcu: Check for callback invocation from offline CPUs Because quiescent states are now reported from offline CPUs in CPU_DYING state, there is some possibility that such a CPU might note the end of a grace period and attempt to start invoking callbacks. This would be a very bad thing, and is supposed to be prevented by the fact that the CPU_DYING CPU gets rid of all its callbacks before reporting the quiescent state. However, there is other CPU-offline code in the kernel, and it is quite possible that someone will invoke RCU core processing from that code. Therefore, this commit adds a warning for this case. Signed-off-by: Paul E. McKenney Signed-off-by: Paul E. McKenney --- diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 575f91d03f06..ac3a810d2db7 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -1373,6 +1373,7 @@ static void rcu_do_batch(struct rcu_state *rsp, struct rcu_data *rdp) * races with call_rcu() from interrupt handlers. */ local_irq_save(flags); + WARN_ON_ONCE(cpu_is_offline(smp_processor_id())); bl = rdp->blimit; trace_rcu_batch_start(rsp->name, rdp->qlen_lazy, rdp->qlen, bl); list = rdp->nxtlist;