Commit-ID: 6296ace467c8640317414ba589b124323806f7ce Gitweb: http://git.kernel.org/tip/6296ace467c8640317414ba589b124323806f7ce Author: Li Zhong <zh...@linux.vnet.ibm.com> AuthorDate: Sun, 28 Apr 2013 11:25:58 +0800 Committer: Ingo Molnar <mi...@kernel.org> CommitDate: Mon, 29 Apr 2013 13:17:33 +0200
nohz: Protect smp_processor_id() in tick_nohz_task_switch() I saw following error when testing the latest nohz code on Power: [ 85.295384] BUG: using smp_processor_id() in preemptible [00000000] code: rsyslogd/3493 [ 85.295396] caller is .tick_nohz_task_switch+0x1c/0xb8 [ 85.295402] Call Trace: [ 85.295408] [c0000001fababab0] [c000000000012dc4] .show_stack+0x110/0x25c (unreliable) [ 85.295420] [c0000001fababba0] [c0000000007c4b54] .dump_stack+0x20/0x30 [ 85.295430] [c0000001fababc10] [c00000000044eb74] .debug_smp_processor_id+0xf4/0x124 [ 85.295438] [c0000001fababca0] [c0000000000d7594] .tick_nohz_task_switch+0x1c/0xb8 [ 85.295447] [c0000001fababd20] [c0000000000b9748] .finish_task_switch+0x13c/0x160 [ 85.295455] [c0000001fababdb0] [c0000000000bbe50] .schedule_tail+0x50/0x124 [ 85.295463] [c0000001fababe30] [c000000000009dc8] .ret_from_fork+0x4/0x54 The code below moves the test into local_irq_save/restore section to avoid the above complaint. Signed-off-by: Li Zhong <zh...@linux.vnet.ibm.com> Acked-by: Frederic Weisbecker <fweis...@gmail.com> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Paul McKenney <paul...@linux.vnet.ibm.com> Link: http://lkml.kernel.org/r/1367119558.6391.34.ca...@thinkpad-t5421.cn.ibm.com Signed-off-by: Ingo Molnar <mi...@kernel.org> --- kernel/time/tick-sched.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index da53c8f..1c9f53b 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -251,14 +251,15 @@ void tick_nohz_task_switch(struct task_struct *tsk) { unsigned long flags; - if (!tick_nohz_full_cpu(smp_processor_id())) - return; - local_irq_save(flags); + if (!tick_nohz_full_cpu(smp_processor_id())) + goto out; + if (tick_nohz_tick_stopped() && !can_stop_full_tick()) tick_nohz_full_kick(); +out: local_irq_restore(flags); } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
