On Fri, 18 Dec 2015, Sasha Levin wrote: > [ 531.164630] RIP vmstat_update (mm/vmstat.c:1408)
Hmmm.. Yes we need to fold the diffs first before disabling the timer otherwise the shepherd task may intervene. Does this patch fix it? Subject: quiet_vmstat: Avoid race with shepherd by folding counters first We need to fold the counters first otherwise the shepherd task may remotely reactivate the vmstat worker. This also avoids the strange loop. Nothing can really increase the counters at that point since we are in the cpu idle loop. So folding the counters once is enough. Cancelling work that does not exist is fine too so just avoid the branches completely. Signed-off-by: Christoph Lameter <c...@linux.com> Index: linux/mm/vmstat.c =================================================================== --- linux.orig/mm/vmstat.c +++ linux/mm/vmstat.c @@ -1419,11 +1419,9 @@ void quiet_vmstat(void) if (system_state != SYSTEM_RUNNING) return; - do { - if (!cpumask_test_and_set_cpu(smp_processor_id(), cpu_stat_off)) - cancel_delayed_work(this_cpu_ptr(&vmstat_work)); - - } while (refresh_cpu_vm_stats(false)); + refresh_cpu_vm_stats(false); + cancel_delayed_work(this_cpu_ptr(&vmstat_work)); + cpumask_set_cpu(smp_processor_id(), cpu_stat_off); } /* -- 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/