diff options
Diffstat (limited to 'debian/patches-rt/0015-sched-lockdep-Annotate-pi_lock-recursion.patch')
| -rw-r--r-- | debian/patches-rt/0015-sched-lockdep-Annotate-pi_lock-recursion.patch | 52 |
1 files changed, 52 insertions, 0 deletions
diff --git a/debian/patches-rt/0015-sched-lockdep-Annotate-pi_lock-recursion.patch b/debian/patches-rt/0015-sched-lockdep-Annotate-pi_lock-recursion.patch new file mode 100644 index 000000000..05030516b --- /dev/null +++ b/debian/patches-rt/0015-sched-lockdep-Annotate-pi_lock-recursion.patch @@ -0,0 +1,52 @@ +From c0e34a5ef4e854220a216e934ab90f04d4432bdd Mon Sep 17 00:00:00 2001 +From: Peter Zijlstra <peterz@infradead.org> +Date: Fri, 23 Oct 2020 12:12:12 +0200 +Subject: [PATCH 015/323] sched, lockdep: Annotate ->pi_lock recursion +Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.10/older/patches-5.10.204-rt100.tar.xz + +There's a valid ->pi_lock recursion issue where the actual PI code +tries to wake up the stop task. Make lockdep aware so it doesn't +complain about this. + +Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> +Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> +--- + kernel/sched/core.c | 15 +++++++++++++++ + 1 file changed, 15 insertions(+) + +diff --git a/kernel/sched/core.c b/kernel/sched/core.c +index 2517a003295b..abbf01f77a76 100644 +--- a/kernel/sched/core.c ++++ b/kernel/sched/core.c +@@ -2670,6 +2670,7 @@ int select_task_rq(struct task_struct *p, int cpu, int sd_flags, int wake_flags) + + void sched_set_stop_task(int cpu, struct task_struct *stop) + { ++ static struct lock_class_key stop_pi_lock; + struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 }; + struct task_struct *old_stop = cpu_rq(cpu)->stop; + +@@ -2685,6 +2686,20 @@ void sched_set_stop_task(int cpu, struct task_struct *stop) + sched_setscheduler_nocheck(stop, SCHED_FIFO, ¶m); + + stop->sched_class = &stop_sched_class; ++ ++ /* ++ * The PI code calls rt_mutex_setprio() with ->pi_lock held to ++ * adjust the effective priority of a task. As a result, ++ * rt_mutex_setprio() can trigger (RT) balancing operations, ++ * which can then trigger wakeups of the stop thread to push ++ * around the current task. ++ * ++ * The stop task itself will never be part of the PI-chain, it ++ * never blocks, therefore that ->pi_lock recursion is safe. ++ * Tell lockdep about this by placing the stop->pi_lock in its ++ * own class. ++ */ ++ lockdep_set_class(&stop->pi_lock, &stop_pi_lock); + } + + cpu_rq(cpu)->stop = stop; +-- +2.43.0 + |