This is a note to let you know that I've just added the patch titled
sched/core: Allow try_invoke_on_locked_down_task() with irqs disabled
to the 5.11-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
sched-core-allow-try_invoke_on_locked_down_task-with-irqs-disabled.patch
and it can be found in the queue-5.11 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 1b7af295541d75535374325fd617944534853919 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Date: Sat, 29 Aug 2020 10:22:24 -0700
Subject: sched/core: Allow try_invoke_on_locked_down_task() with irqs disabled
From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
commit 1b7af295541d75535374325fd617944534853919 upstream.
The try_invoke_on_locked_down_task() function currently requires
that interrupts be enabled, but it is called with interrupts
disabled from rcu_print_task_stall(), resulting in an "IRQs not
enabled as expected" diagnostic. This commit therefore updates
try_invoke_on_locked_down_task() to use raw_spin_lock_irqsave() instead
of raw_spin_lock_irq(), thus allowing use from either context.
Link: https://lore.kernel.org/lkml/000000000000903d5805ab908fc4@xxxxxxxxxx/
Link: https://lore.kernel.org/lkml/20200928075729.GC2611@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/
Reported-by: syzbot+cb3b69ae80afd6535b0e@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/sched/core.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3478,7 +3478,7 @@ out:
/**
* try_invoke_on_locked_down_task - Invoke a function on task in fixed state
- * @p: Process for which the function is to be invoked.
+ * @p: Process for which the function is to be invoked, can be @current.
* @func: Function to invoke.
* @arg: Argument to function.
*
@@ -3496,12 +3496,11 @@ out:
*/
bool try_invoke_on_locked_down_task(struct task_struct *p, bool (*func)(struct task_struct *t, void *arg), void *arg)
{
- bool ret = false;
struct rq_flags rf;
+ bool ret = false;
struct rq *rq;
- lockdep_assert_irqs_enabled();
- raw_spin_lock_irq(&p->pi_lock);
+ raw_spin_lock_irqsave(&p->pi_lock, rf.flags);
if (p->on_rq) {
rq = __task_rq_lock(p, &rf);
if (task_rq(p) == rq)
@@ -3518,7 +3517,7 @@ bool try_invoke_on_locked_down_task(stru
ret = func(p, arg);
}
}
- raw_spin_unlock_irq(&p->pi_lock);
+ raw_spin_unlock_irqrestore(&p->pi_lock, rf.flags);
return ret;
}
Patches currently in stable-queue which might be from peterz@xxxxxxxxxxxxx are
queue-5.11/sched-core-allow-try_invoke_on_locked_down_task-with-irqs-disabled.patch
