From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steven Rostedt Subject: [PATCH RT 01/24] sched/fair: Fix CFS bandwidth control lockdep DEADLOCK report Date: Fri, 07 Sep 2018 16:58:58 -0400 Message-ID: <20180907205929.901024799@goodmis.org> References: <20180907205857.262840394@goodmis.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Cc: Thomas Gleixner , Carsten Emde , Sebastian Andrzej Siewior , John Kacur , Paul Gortmaker , Julia Cartwright , Daniel Wagner , tom.zanussi@linux.intel.com, stable-rt@vger.kernel.org, Mike Galbraith To: linux-kernel@vger.kernel.org, linux-rt-users Return-path: Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-rt-users.vger.kernel.org 4.14.63-rt41-rc2 stable review patch. If anyone has any objections, please let me know. ------------------ From: Mike Galbraith [ Upstream commit df7e8acc0c9a84979a448d215b8ef889efe4ac5a ] CFS bandwidth control yields the inversion gripe below, moving handling quells it. |======================================================== |WARNING: possible irq lock inversion dependency detected |4.16.7-rt1-rt #2 Tainted: G E |-------------------------------------------------------- |sirq-hrtimer/0/15 just changed the state of lock: | (&cfs_b->lock){+...}, at: [<000000009adb5cf7>] sched_cfs_period_timer+0x28/0x140 |but this lock was taken by another, HARDIRQ-safe lock in the past: (&rq->lock){-...} |and interrupts could create inverse lock ordering between them. |other info that might help us debug this: | Possible interrupt unsafe locking scenario: | CPU0 CPU1 | ---- ---- | lock(&cfs_b->lock); | local_irq_disable(); | lock(&rq->lock); | lock(&cfs_b->lock); | | lock(&rq->lock); Cc: stable-rt@vger.kernel.org Acked-by: Steven Rostedt (VMware) Signed-off-by: Mike Galbraith Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Steven Rostedt (VMware) --- kernel/sched/fair.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 36ef77839be4..51ecea4f5d16 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -4684,9 +4684,9 @@ void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b) cfs_b->period = ns_to_ktime(default_cfs_period()); INIT_LIST_HEAD(&cfs_b->throttled_cfs_rq); - hrtimer_init(&cfs_b->period_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS_PINNED); + hrtimer_init(&cfs_b->period_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS_PINNED_HARD); cfs_b->period_timer.function = sched_cfs_period_timer; - hrtimer_init(&cfs_b->slack_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); + hrtimer_init(&cfs_b->slack_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD); cfs_b->slack_timer.function = sched_cfs_slack_timer; } -- 2.18.0