The patch titled
keep rd->online and cpu_online_map in sync
has been added to the -mm tree. Its filename is
keep-rd-online-and-cpu_online_map-in-sync.patch
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------------------------------------------------------
Subject: keep rd->online and cpu_online_map in sync
From: Gregory Haskins <ghaskins@xxxxxxxxxx>
It is possible to allow the root-domain cache of online cpus to become out of
sync with the global cpu_online_map. This is because we currently trigger
removal of cpus too early in the notifier chain. Other DOWN_PREPARE handlers
may in fact run and reconfigure the root-domain topology, thereby stomping on
our own offline handling.
The end result is that rd->online may become out of sync with cpu_online_map,
which results in potential task misrouting.
So change the offline handling to be more tightly coupled with the global
offline process by triggering on CPU_DYING intead of CPU_DOWN_PREPARE.
Signed-off-by: Gregory Haskins <ghaskins@xxxxxxxxxx>
Cc: Gautham R Shenoy <ego@xxxxxxxxxx>
Cc: "Siddha, Suresh B" <suresh.b.siddha@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: "Rafael J. Wysocki" <rjw@xxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/sched.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff -puN kernel/sched.c~keep-rd-online-and-cpu_online_map-in-sync kernel/sched.c
--- a/kernel/sched.c~keep-rd-online-and-cpu_online_map-in-sync
+++ a/kernel/sched.c
@@ -5956,7 +5956,8 @@ migration_call(struct notifier_block *nf
spin_unlock_irq(&rq->lock);
break;
- case CPU_DOWN_PREPARE:
+ case CPU_DYING:
+ case CPU_DYING_FROZEN:
/* Update our root-domain */
rq = cpu_rq(cpu);
spin_lock_irqsave(&rq->lock, flags);
_
Patches currently in -mm which might be from ghaskins@xxxxxxxxxx are
git-kvm.patch
keep-rd-online-and-cpu_online_map-in-sync.patch
cpu-hotplug-register-update_sched_domains-notifier-with-higher-prio.patch
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