From: Peter Zijlstra peterz@infradead.org
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@google.com/ Link: https://lore.kernel.org/lkml/20200928075729.GC2611@hirez.programming.kicks-a... Reported-by: syzbot+cb3b69ae80afd6535b0e@syzkaller.appspotmail.com Signed-off-by: Peter Zijlstra peterz@infradead.org Signed-off-by: Paul E. McKenney paulmck@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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; }