Commit 001c28e5 authored Jan 20, 2023 by Nicholas Piggin Committed by Peter Zijlstra Jan 21, 2023

exit: Detect and fix irq disabled state in oops



If a task oopses with irqs disabled, this can cause various cascading
problems in the oops path such as sleep-from-invalid warnings, and
potentially worse.

Since commit 0258b5fd ("coredump: Limit coredumps to a single
thread group"), the unconditional irq enable in coredump_task_exit()
will "fix" the irq state to be enabled early in do_exit(), so currently
this may not be triggerable, but that is coincidental and fragile.

Detect and fix the irqs_disabled() condition in the oops path before
calling do_exit(), similarly to the way in_atomic() is handled.

Reported-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Link: https://lore.kernel.org/lkml/20221004094401.708299-1-npiggin@gmail.com/

parent 19235e47

kernel/exit.c

+7 −0

Original line number	Diff line number	Diff line
		@@ -807,6 +807,8 @@ void __noreturn do_exit(long code)
		struct task_struct *tsk = current;
		int group_dead;

		WARN_ON(irqs_disabled());

		synchronize_group_exit(tsk, code);

		WARN_ON(tsk->plug);
		@@ -938,6 +940,11 @@ void __noreturn make_task_dead(int signr)
		if (unlikely(!tsk->pid))
		panic("Attempted to kill the idle task!");

		if (unlikely(irqs_disabled())) {
		pr_info("note: %s[%d] exited with irqs disabled\n",
		current->comm, task_pid_nr(current));
		local_irq_enable();
		}
		if (unlikely(in_atomic())) {
		pr_info("note: %s[%d] exited with preempt_count %d\n",
		current->comm, task_pid_nr(current),