kernel: treat PF_IO_WORKER like PF_KTHREAD for ptrace/signals

Signed-off-by: Jens Axboe <axboe@kernel.dk>

kernel/ptrace.c

@@ -375,7 +375,7 @@ static int ptrace_attach(struct task_struct *task, long request,
 	audit_ptrace(task);
 
 	retval = -EPERM;
-	if (unlikely(task->flags & PF_KTHREAD))
+	if (unlikely(task->flags & (PF_KTHREAD | PF_IO_WORKER)))
 		goto out;
 	if (same_thread_group(task, current))
 		goto out;

kernel/signal.c

@@ -91,7 +91,7 @@ static bool sig_task_ignored(struct task_struct *t, int sig, bool force)
 		return true;
 
 	/* Only allow kernel generated signals to this kthread */
-	if (unlikely((t->flags & PF_KTHREAD) &&
+	if (unlikely((t->flags & (PF_KTHREAD | PF_IO_WORKER)) &&
 		     (handler == SIG_KTHREAD_KERNEL) && !force))
 		return true;
 
@@ -1096,7 +1096,7 @@ static int __send_signal(int sig, struct kernel_siginfo *info, struct task_struc
 	/*
 	 * Skip useless siginfo allocation for SIGKILL and kernel threads.
 	 */
-	if ((sig == SIGKILL) || (t->flags & PF_KTHREAD))
+	if ((sig == SIGKILL) || (t->flags & (PF_KTHREAD | PF_IO_WORKER)))
 		goto out_set;
 
 	/*