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Date: Wed, 11 Nov 2020 16:30:37 -0500
From: Steven Rostedt <rostedt@...dmis.org>
To: LKML <linux-kernel@...r.kernel.org>,
linux-rt-users <linux-rt-users@...r.kernel.org>
Cc: Thomas Gleixner <tglx@...utronix.de>,
Carsten Emde <C.Emde@...dl.org>,
John Kacur <jkacur@...hat.com>,
Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
Daniel Wagner <wagi@...om.org>,
Tom Zanussi <zanussi@...nel.org>,
"Srivatsa S. Bhat" <srivatsa@...il.mit.edu>
Subject: [ANNOUNCE] 5.4.74-rt42
Dear RT Folks,
I'm pleased to announce the 5.4.74-rt42 stable release.
You can get this release via the git tree at:
git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-stable-rt.git
branch: v5.4-rt
Head SHA1: c8dd266abfd2094d00758c27f7c37b78264f9666
Or to build 5.4.74-rt42 directly, the following patches should be applied:
http://www.kernel.org/pub/linux/kernel/v5.x/linux-5.4.tar.xz
http://www.kernel.org/pub/linux/kernel/v5.x/patch-5.4.74.xz
http://www.kernel.org/pub/linux/kernel/projects/rt/5.4/patch-5.4.74-rt42.patch.xz
You can also build from 5.4.74-rt41 by applying the incremental patch:
http://www.kernel.org/pub/linux/kernel/projects/rt/5.4/incr/patch-5.4.74-rt41-rt42.patch.xz
Enjoy,
-- Steve
Changes from v5.4.74-rt41:
---
Oleg Nesterov (1):
ptrace: fix ptrace_unfreeze_traced() race with rt-lock
Sebastian Andrzej Siewior (3):
net: Properly annotate the try-lock for the seqlock
mm/memcontrol: Disable preemption in __mod_memcg_lruvec_state()
timers: Don't block on ->expiry_lock for TIMER_IRQSAFE
Steven Rostedt (VMware) (1):
Linux 5.4.74-rt42
----
include/linux/seqlock.h | 9 ---------
include/net/sch_generic.h | 10 +++++++++-
kernel/ptrace.c | 23 +++++++++++++++--------
kernel/time/timer.c | 9 ++++++++-
localversion-rt | 2 +-
mm/memcontrol.c | 2 ++
6 files changed, 35 insertions(+), 20 deletions(-)
---------------------------
diff --git a/include/linux/seqlock.h b/include/linux/seqlock.h
index e5207897c33e..f390293974ea 100644
--- a/include/linux/seqlock.h
+++ b/include/linux/seqlock.h
@@ -489,15 +489,6 @@ static inline void write_seqlock(seqlock_t *sl)
__raw_write_seqcount_begin(&sl->seqcount);
}
-static inline int try_write_seqlock(seqlock_t *sl)
-{
- if (spin_trylock(&sl->lock)) {
- __raw_write_seqcount_begin(&sl->seqcount);
- return 1;
- }
- return 0;
-}
-
static inline void write_sequnlock(seqlock_t *sl)
{
__raw_write_seqcount_end(&sl->seqcount);
diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
index e6afb4b9cede..112d2dca8b08 100644
--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h
@@ -168,8 +168,16 @@ static inline bool qdisc_run_begin(struct Qdisc *qdisc)
return false;
}
#ifdef CONFIG_PREEMPT_RT
- if (try_write_seqlock(&qdisc->running))
+ if (spin_trylock(&qdisc->running.lock)) {
+ seqcount_t *s = &qdisc->running.seqcount;
+ /*
+ * Variant of write_seqcount_t_begin() telling lockdep that a
+ * trylock was attempted.
+ */
+ __raw_write_seqcount_begin(s);
+ seqcount_acquire(&s->dep_map, 0, 1, _RET_IP_);
return true;
+ }
return false;
#else
/* Variant of write_seqcount_begin() telling lockdep a trylock
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 3075006d720e..3f7156f06b6c 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -197,8 +197,8 @@ static bool ptrace_freeze_traced(struct task_struct *task)
static void ptrace_unfreeze_traced(struct task_struct *task)
{
- if (task->state != __TASK_TRACED)
- return;
+ unsigned long flags;
+ bool frozen = true;
WARN_ON(!task->ptrace || task->parent != current);
@@ -207,12 +207,19 @@ static void ptrace_unfreeze_traced(struct task_struct *task)
* Recheck state under the lock to close this race.
*/
spin_lock_irq(&task->sighand->siglock);
- if (task->state == __TASK_TRACED) {
- if (__fatal_signal_pending(task))
- wake_up_state(task, __TASK_TRACED);
- else
- task->state = TASK_TRACED;
- }
+
+ raw_spin_lock_irqsave(&task->pi_lock, flags);
+ if (task->state == __TASK_TRACED)
+ task->state = TASK_TRACED;
+ else if (task->saved_state == __TASK_TRACED)
+ task->saved_state = TASK_TRACED;
+ else
+ frozen = false;
+ raw_spin_unlock_irqrestore(&task->pi_lock, flags);
+
+ if (frozen && __fatal_signal_pending(task))
+ wake_up_state(task, __TASK_TRACED);
+
spin_unlock_irq(&task->sighand->siglock);
}
diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index 89078fd848b9..3e9d7f227a5c 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -1289,7 +1289,7 @@ static void del_timer_wait_running(struct timer_list *timer)
u32 tf;
tf = READ_ONCE(timer->flags);
- if (!(tf & TIMER_MIGRATING)) {
+ if (!(tf & (TIMER_MIGRATING | TIMER_IRQSAFE))) {
struct timer_base *base = get_timer_base(tf);
/*
@@ -1373,6 +1373,13 @@ int del_timer_sync(struct timer_list *timer)
*/
WARN_ON(in_irq() && !(timer->flags & TIMER_IRQSAFE));
+ /*
+ * Must be able to sleep on PREEMPT_RT because of the slowpath in
+ * del_timer_wait_running().
+ */
+ if (IS_ENABLED(CONFIG_PREEMPT_RT) && !(timer->flags & TIMER_IRQSAFE))
+ might_sleep();
+
do {
ret = try_to_del_timer_sync(timer);
diff --git a/localversion-rt b/localversion-rt
index 629e0b4384b8..8bdfb9a04683 100644
--- a/localversion-rt
+++ b/localversion-rt
@@ -1 +1 @@
--rt41
+-rt42
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 9bdb75ef6d62..c9d02e2272e1 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -752,6 +752,7 @@ void __mod_lruvec_state(struct lruvec *lruvec, enum node_stat_item idx,
pn = container_of(lruvec, struct mem_cgroup_per_node, lruvec);
memcg = pn->memcg;
+ preempt_disable_rt();
/* Update memcg */
__mod_memcg_state(memcg, idx, val);
@@ -767,6 +768,7 @@ void __mod_lruvec_state(struct lruvec *lruvec, enum node_stat_item idx,
x = 0;
}
__this_cpu_write(pn->lruvec_stat_cpu->count[idx], x);
+ preempt_enable_rt();
}
void __mod_lruvec_slab_state(void *p, enum node_stat_item idx, int val)
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