Messages in this thread Patch in this message | | | Subject | [PATCH] cpu hotplug fixes for dependent_sleeper and wake_sleeping_dependent | From | Nathan Lynch <> | Date | Mon, 30 Aug 2004 04:41:16 -0500 |
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Hi-
I've reported this issue a couple of times and I think I've finally tracked it down, though I don't know whether I've come up with the best fix.
To recap, offlining a cpu with current bk results in the "Aiee, killing interrupt handler!" panic from do_exit(). This seems to be triggered only with CONFIG_PREEMPT and CONFIG_SCHED_SMT both enabled. I believe the problem is that when do_stop() calls schedule(), dependent_sleeper() drops the "offline" cpu's rq->lock and never reacquires it.
The following seems to work (tested on ppc64). Is there a better way?
Nathan
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Return early from dependent_sleeper and wake_sleeping_dependent if this_cpu is offline to avoid releasing this_cpu's rq->lock.
Signed-off-by: Nathan Lynch <nathanl@austin.ibm.com>
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diff -puN kernel/sched.c~sched-smt-cpu-hotplug-fix kernel/sched.c --- 2.6-bk/kernel/sched.c~sched-smt-cpu-hotplug-fix 2004-08-30 04:22:49.000000000 -0500 +++ 2.6-bk-nathanl/kernel/sched.c 2004-08-30 04:23:28.000000000 -0500 @@ -2502,7 +2502,7 @@ static inline void wake_sleeping_depende cpumask_t sibling_map; int i; - if (!(sd->flags & SD_SHARE_CPUPOWER)) + if (!(sd->flags & SD_SHARE_CPUPOWER) || cpu_is_offline(this_cpu)) return; /* @@ -2549,7 +2549,7 @@ static inline int dependent_sleeper(int int ret = 0, i; task_t *p; - if (!(sd->flags & SD_SHARE_CPUPOWER)) + if (!(sd->flags & SD_SHARE_CPUPOWER) || cpu_is_offline(this_cpu)) return 0; /* _
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