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)
