exit: Detect and fix irq disabled state in oops

[ Upstream commit 001c28e57187570e4b5aa4492c7a957fb6d65d7b ]

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 0258b5fd7c712 ("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/
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/kernel/exit.c b/kernel/exit.c
index 15dc2ec..bccfa42 100644 (file)
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -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),