diff options
| author | Paolo Valente <paolo.valente@linaro.org> | 2020-03-21 10:45:21 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-04-23 10:36:26 +0200 |
| commit | a362482b2325fc5fb522b1786225fb8d868590c5 (patch) | |
| tree | c1b8db7914414c4075cc852bafc78d2ab5ee373b /block | |
| parent | 839b7cd1d8bce99a04a77ba69105c8277c77ee15 (diff) | |
block, bfq: invoke flush_idle_tree after reparent_active_queues in pd_offline
commit 4d38a87fbb77fb9ff2ff4e914162a8ae6453eff5 upstream.
In bfq_pd_offline(), the function bfq_flush_idle_tree() is invoked to
flush the rb tree that contains all idle entities belonging to the pd
(cgroup) being destroyed. In particular, bfq_flush_idle_tree() is
invoked before bfq_reparent_active_queues(). Yet the latter may happen
to add some entities to the idle tree. It happens if, in some of the
calls to bfq_bfqq_move() performed by bfq_reparent_active_queues(),
the queue to move is empty and gets expired.
This commit simply reverses the invocation order between
bfq_flush_idle_tree() and bfq_reparent_active_queues().
Tested-by: cki-project@redhat.com
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'block')
| -rw-r--r-- | block/bfq-cgroup.c | 20 |
1 files changed, 13 insertions, 7 deletions
diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c index 85c3a2bd6911..12b707a4e52f 100644 --- a/block/bfq-cgroup.c +++ b/block/bfq-cgroup.c @@ -877,13 +877,6 @@ static void bfq_pd_offline(struct blkg_policy_data *pd) st = bfqg->sched_data.service_tree + i; /* - * The idle tree may still contain bfq_queues belonging - * to exited task because they never migrated to a different - * cgroup from the one being destroyed now. - */ - bfq_flush_idle_tree(st); - - /* * It may happen that some queues are still active * (busy) upon group destruction (if the corresponding * processes have been forced to terminate). We move @@ -896,6 +889,19 @@ static void bfq_pd_offline(struct blkg_policy_data *pd) * scheduler has taken no reference. */ bfq_reparent_active_queues(bfqd, bfqg, st, i); + + /* + * The idle tree may still contain bfq_queues + * belonging to exited task because they never + * migrated to a different cgroup from the one being + * destroyed now. In addition, even + * bfq_reparent_active_queues() may happen to add some + * entities to the idle tree. It happens if, in some + * of the calls to bfq_bfqq_move() performed by + * bfq_reparent_active_queues(), the queue to move is + * empty and gets expired. + */ + bfq_flush_idle_tree(st); } __bfq_deactivate_entity(entity, false); |