Messages in this thread | | | Date | Tue, 29 Jul 2014 11:47:04 -0400 | From | Sasha Levin <> | Subject | Re: vmstat: On demand vmstat workers V8 |
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On 07/29/2014 11:39 AM, Christoph Lameter wrote: > On Tue, 29 Jul 2014, Tejun Heo wrote: > >> Hmmm, well, then it's something else. Either a bug in workqueue or in >> the caller. Given the track record, the latter is more likely. >> e.g. it looks kinda suspicious that the work func is cleared after >> cancel_delayed_work_sync() is called. What happens if somebody tries >> to schedule it inbetween? > > Here is yet another patch to also address this idea: > > Subject: vmstat: Clear the work.func before cancelling delayed work > > Looks strange to me but Tejun thinks this could do some good. > If this really is the right thing to do then cancel_delayed_work should > zap the work func itselt I think. > > Signed-off-by: Christoph Lameter <cl@linux.com> > > > Index: linux/mm/vmstat.c > =================================================================== > --- linux.orig/mm/vmstat.c 2014-07-29 10:22:45.073884943 -0500 > +++ linux/mm/vmstat.c 2014-07-29 10:34:45.083369228 -0500 > @@ -1277,8 +1277,8 @@ static int vmstat_cpuup_callback(struct > break; > case CPU_DOWN_PREPARE: > case CPU_DOWN_PREPARE_FROZEN: > - cancel_delayed_work_sync(&per_cpu(vmstat_work, cpu)); > per_cpu(vmstat_work, cpu).work.func = NULL; > + cancel_delayed_work_sync(&per_cpu(vmstat_work, cpu)); > break; > case CPU_DOWN_FAILED: > case CPU_DOWN_FAILED_FROZEN: >
I'm slightly confused here. The on demand vmstat workers patch did this:
case CPU_DOWN_PREPARE_FROZEN: - cancel_delayed_work_sync(&per_cpu(vmstat_work, cpu)); - per_cpu(vmstat_work, cpu).work.func = NULL; + if (!cpumask_test_and_set_cpu(cpu, cpu_stat_off)) + cancel_delayed_work_sync(&per_cpu(vmstat_work, cpu));
So your new patch doesn't apply on top of it, and doesn't make sense before it.
Thanks, Sasha
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