Dear RT folks!
I'm pleased to announce the v4.19.13-rt10 patch set.
Changes since v4.19.13-rt9:
- Two scheduler timer were moved from hardirq context to softirq.
Patch by Peter Zijlstra.
- Flush I/O while waiting for readlock of a rwsem to avoid I/O
deadlocks. Patch by Scott Wood.
Known issues
- A warning triggered in "rcu_note_context_switch" originated from
SyS_timer_gettime(). The issue was always there, it is now
visible. Reported by Grygorii Strashko and Daniel Wagner.
The delta patch against v4.19.13-rt9 is appended below and can be found here:
https://cdn.kernel.org/pub/linux/kernel/projects/rt/4.19/incr/patch-4.19.13-rt9-rt10.patch.xz
You can get this release via the git tree at:
git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git v4.19.13-rt10
The RT patch against v4.19.13 can be found here:
https://cdn.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patch-4.19.13-rt10.patch.xz
The split quilt queue is available at:
https://cdn.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.13-rt10.tar.xz
Sebastian
diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
index 27f144b2d87b9..bbac843464de1 100644
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -1932,7 +1932,7 @@ rt_mutex_fastlock(struct rt_mutex *lock, int state,
* If rt_mutex blocks, the function sched_submit_work will not call
* blk_schedule_flush_plug (because tsk_is_pi_blocked would be true).
* We must call blk_schedule_flush_plug here, if we don't call it,
- * a deadlock in device mapper may happen.
+ * a deadlock in I/O may happen.
*/
if (unlikely(blk_needs_flush_plug(current)))
blk_schedule_flush_plug(current);
diff --git a/kernel/locking/rwsem-rt.c b/kernel/locking/rwsem-rt.c
index 660e22caf7099..f518495bd6ccd 100644
--- a/kernel/locking/rwsem-rt.c
+++ b/kernel/locking/rwsem-rt.c
@@ -1,5 +1,6 @@
/*
*/
+#include <linux/blkdev.h>
#include <linux/rwsem.h>
#include <linux/sched/debug.h>
#include <linux/sched/signal.h>
@@ -87,6 +88,14 @@ static int __sched __down_read_common(struct rw_semaphore *sem, int state)
if (__down_read_trylock(sem))
return 0;
+ /*
+ * If rt_mutex blocks, the function sched_submit_work will not call
+ * blk_schedule_flush_plug (because tsk_is_pi_blocked would be true).
+ * We must call blk_schedule_flush_plug here, if we don't call it,
+ * a deadlock in I/O may happen.
+ */
+ if (unlikely(blk_needs_flush_plug(current)))
+ blk_schedule_flush_plug(current);
might_sleep();
raw_spin_lock_irq(&m->wait_lock);
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 4d4dbed98adf2..049ff794c74e7 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4554,7 +4554,7 @@ static u64 distribute_cfs_runtime(struct cfs_bandwidth *cfs_b,
struct rq *rq = rq_of(cfs_rq);
struct rq_flags rf;
- rq_lock(rq, &rf);
+ rq_lock_irqsave(rq, &rf);
if (!cfs_rq_throttled(cfs_rq))
goto next;
@@ -4571,7 +4571,7 @@ static u64 distribute_cfs_runtime(struct cfs_bandwidth *cfs_b,
unthrottle_cfs_rq(cfs_rq);
next:
- rq_unlock(rq, &rf);
+ rq_unlock_irqrestore(rq, &rf);
if (!remaining)
break;
@@ -4587,7 +4587,7 @@ static u64 distribute_cfs_runtime(struct cfs_bandwidth *cfs_b,
* period the timer is deactivated until scheduling resumes; cfs_b->idle is
* used to track this state.
*/
-static int do_sched_cfs_period_timer(struct cfs_bandwidth *cfs_b, int overrun)
+static int do_sched_cfs_period_timer(struct cfs_bandwidth *cfs_b, int overrun, unsigned long flags)
{
u64 runtime, runtime_expires;
int throttled;
@@ -4629,11 +4629,11 @@ static int do_sched_cfs_period_timer(struct cfs_bandwidth *cfs_b, int overrun)
while (throttled && cfs_b->runtime > 0 && !cfs_b->distribute_running) {
runtime = cfs_b->runtime;
cfs_b->distribute_running = 1;
- raw_spin_unlock(&cfs_b->lock);
+ raw_spin_unlock_irqrestore(&cfs_b->lock, flags);
/* we can't nest cfs_b->lock while distributing bandwidth */
runtime = distribute_cfs_runtime(cfs_b, runtime,
runtime_expires);
- raw_spin_lock(&cfs_b->lock);
+ raw_spin_lock_irqsave(&cfs_b->lock, flags);
cfs_b->distribute_running = 0;
throttled = !list_empty(&cfs_b->throttled_cfs_rq);
@@ -4742,17 +4742,18 @@ static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq)
static void do_sched_cfs_slack_timer(struct cfs_bandwidth *cfs_b)
{
u64 runtime = 0, slice = sched_cfs_bandwidth_slice();
+ unsigned long flags;
u64 expires;
/* confirm we're still not at a refresh boundary */
- raw_spin_lock(&cfs_b->lock);
+ raw_spin_lock_irqsave(&cfs_b->lock, flags);
if (cfs_b->distribute_running) {
- raw_spin_unlock(&cfs_b->lock);
+ raw_spin_unlock_irqrestore(&cfs_b->lock, flags);
return;
}
if (runtime_refresh_within(cfs_b, min_bandwidth_expiration)) {
- raw_spin_unlock(&cfs_b->lock);
+ raw_spin_unlock_irqrestore(&cfs_b->lock, flags);
return;
}
@@ -4763,18 +4764,18 @@ static void do_sched_cfs_slack_timer(struct cfs_bandwidth *cfs_b)
if (runtime)
cfs_b->distribute_running = 1;
- raw_spin_unlock(&cfs_b->lock);
+ raw_spin_unlock_irqrestore(&cfs_b->lock, flags);
if (!runtime)
return;
runtime = distribute_cfs_runtime(cfs_b, runtime, expires);
- raw_spin_lock(&cfs_b->lock);
+ raw_spin_lock_irqsave(&cfs_b->lock, flags);
if (expires == cfs_b->runtime_expires)
cfs_b->runtime -= min(runtime, cfs_b->runtime);
cfs_b->distribute_running = 0;
- raw_spin_unlock(&cfs_b->lock);
+ raw_spin_unlock_irqrestore(&cfs_b->lock, flags);
}
/*
@@ -4852,20 +4853,21 @@ static enum hrtimer_restart sched_cfs_period_timer(struct hrtimer *timer)
{
struct cfs_bandwidth *cfs_b =
container_of(timer, struct cfs_bandwidth, period_timer);
+ unsigned long flags;
int overrun;
int idle = 0;
- raw_spin_lock(&cfs_b->lock);
+ raw_spin_lock_irqsave(&cfs_b->lock, flags);
for (;;) {
overrun = hrtimer_forward_now(timer, cfs_b->period);
if (!overrun)
break;
- idle = do_sched_cfs_period_timer(cfs_b, overrun);
+ idle = do_sched_cfs_period_timer(cfs_b, overrun, flags);
}
if (idle)
cfs_b->period_active = 0;
- raw_spin_unlock(&cfs_b->lock);
+ raw_spin_unlock_irqrestore(&cfs_b->lock, flags);
return idle ? HRTIMER_NORESTART : HRTIMER_RESTART;
}
@@ -4878,9 +4880,9 @@ 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_HARD);
+ hrtimer_init(&cfs_b->period_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS_PINNED);
cfs_b->period_timer.function = sched_cfs_period_timer;
- hrtimer_init(&cfs_b->slack_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD);
+ hrtimer_init(&cfs_b->slack_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
cfs_b->slack_timer.function = sched_cfs_slack_timer;
cfs_b->distribute_running = 0;
}
diff --git a/localversion-rt b/localversion-rt
index 22746d6390a42..d79dde624aaac 100644
--- a/localversion-rt
+++ b/localversion-rt
@@ -1 +1 @@
--rt9
+-rt10
