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authorJuri Lelli <juri.lelli@redhat.com>2019-07-19 15:59:59 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-10-05 15:11:31 +0200
commit1b2a1a99a361f91610493b158ffb13c66921939a (patch)
tree0f57436673b5570ef9ae822d604ac90876e30f11 /kernel
parent387d74e9bdb0f9c6f2eaa443e6f9b2f4a9d10714 (diff)
rcu/tree: Call setschedule() gp ktread to SCHED_FIFO outside of atomic region
[ Upstream commit 1a763fd7c6335e3122c1cc09576ef6c99ada4267 ] sched_setscheduler() needs to acquire cpuset_rwsem, but it is currently called from an invalid (atomic) context by rcu_spawn_gp_kthread(). Fix that by simply moving sched_setscheduler_nocheck() call outside of the atomic region, as it doesn't actually require to be guarded by rcu_node lock. Suggested-by: Peter Zijlstra <peterz@infradead.org> Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com> Signed-off-by: Juri Lelli <juri.lelli@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: bristot@redhat.com Cc: claudio@evidence.eu.com Cc: lizefan@huawei.com Cc: longman@redhat.com Cc: luca.abeni@santannapisa.it Cc: mathieu.poirier@linaro.org Cc: rostedt@goodmis.org Cc: tj@kernel.org Cc: tommaso.cucinotta@santannapisa.it Link: https://lkml.kernel.org/r/20190719140000.31694-8-juri.lelli@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/rcu/tree.c6
1 files changed, 3 insertions, 3 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index a14e5fbbea46..eb764c24bc4d 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3234,13 +3234,13 @@ static int __init rcu_spawn_gp_kthread(void)
t = kthread_create(rcu_gp_kthread, NULL, "%s", rcu_state.name);
if (WARN_ONCE(IS_ERR(t), "%s: Could not start grace-period kthread, OOM is now expected behavior\n", __func__))
return 0;
+ if (kthread_prio)
+ sched_setscheduler_nocheck(t, SCHED_FIFO, &sp);
rnp = rcu_get_root();
raw_spin_lock_irqsave_rcu_node(rnp, flags);
rcu_state.gp_kthread = t;
- if (kthread_prio) {
+ if (kthread_prio)
sp.sched_priority = kthread_prio;
- sched_setscheduler_nocheck(t, SCHED_FIFO, &sp);
- }
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
wake_up_process(t);
rcu_spawn_nocb_kthreads();