diff options
| author | Konstantin Khlebnikov <khlebnikov@yandex-team.ru> | 2016-06-16 15:57:01 +0300 |
|---|---|---|
| committer | Sasha Levin <alexander.levin@verizon.com> | 2017-06-13 09:29:21 -0400 |
| commit | 709dcf11a35318f4d9b8aeb0c5c144fd59fbabc1 (patch) | |
| tree | 1d581bc967003052bf63cb13590c28c99bf06604 | |
| parent | 0f665ed5581f1c4e6cf1353484a0f625b2bf88a0 (diff) | |
sched/fair: Initialize throttle_count for new task-groups lazily
[ Upstream commit 094f469172e00d6ab0a3130b0e01c83b3cf3a98d ]
Cgroup created inside throttled group must inherit current throttle_count.
Broken throttle_count allows to nominate throttled entries as a next buddy,
later this leads to null pointer dereference in pick_next_task_fair().
This patch initialize cfs_rq->throttle_count at first enqueue: laziness
allows to skip locking all rq at group creation. Lazy approach also allows
to skip full sub-tree scan at throttling hierarchy (not in this patch).
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bsegall@google.com
Link: http://lkml.kernel.org/r/146608182119.21870.8439834428248129633.stgit@buzz
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
| -rw-r--r-- | kernel/sched/fair.c | 20 | ||||
| -rw-r--r-- | kernel/sched/sched.h | 2 |
2 files changed, 21 insertions, 1 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index a7039e128a73..13d351e7c726 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -3961,6 +3961,26 @@ static void check_enqueue_throttle(struct cfs_rq *cfs_rq) if (!cfs_bandwidth_used()) return; + /* Synchronize hierarchical throttle counter: */ + if (unlikely(!cfs_rq->throttle_uptodate)) { + struct rq *rq = rq_of(cfs_rq); + struct cfs_rq *pcfs_rq; + struct task_group *tg; + + cfs_rq->throttle_uptodate = 1; + + /* Get closest up-to-date node, because leaves go first: */ + for (tg = cfs_rq->tg->parent; tg; tg = tg->parent) { + pcfs_rq = tg->cfs_rq[cpu_of(rq)]; + if (pcfs_rq->throttle_uptodate) + break; + } + if (tg) { + cfs_rq->throttle_count = pcfs_rq->throttle_count; + cfs_rq->throttled_clock_task = rq_clock_task(rq); + } + } + /* an active group must be handled by the update_curr()->put() path */ if (!cfs_rq->runtime_enabled || cfs_rq->curr) return; diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index aa1f059de4f7..f4fc533b66bc 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -414,7 +414,7 @@ struct cfs_rq { u64 throttled_clock, throttled_clock_task; u64 throttled_clock_task_time; - int throttled, throttle_count; + int throttled, throttle_count, throttle_uptodate; struct list_head throttled_list; #endif /* CONFIG_CFS_BANDWIDTH */ #endif /* CONFIG_FAIR_GROUP_SCHED */ |