Messages in this thread | | | Date | Thu, 28 Feb 2008 21:01:40 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH] fix boot-time hangs from PREEMPT_RCU and NO_HZ |
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On Thu, 28 Feb 2008 20:43:29 -0800 "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> wrote:
> This is a repost of http://lkml.org/lkml/2008/2/2/11. It is needed in > 2.6.25 in order to prevent boot-time hangs when running with PREEMPT_RCU > and NO_HZ. > > Preemptible RCU can get stuck if a CPU goes idle and NO_HZ is set. The > idle CPU will not progress the RCU through its grace period, so that > any subsequent synchronize_rcu() invocations can hang until such time > as a process starts running on the idle CPU. If no such process runs, > subsequent synchronize_rcu() invocations will hang indefinitely, in turn > hanging the system. Without this patch, one of Steve Rostedt's boxes > hangs on boot when PREEMPT_RCU and NO_HZ are set. That same box boots > fine with this patch. > > Note: This patch came directly from the -rt patch where it has been tested > for several months. > > Andrew, could you please apply this?
I already have it, via git-sched. Presumably Ingo has it lined up for the next sched-related merge.
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