kernel: don't call do_exit() for PF_IO_WORKER threads

stable inclusion
from stable-v5.10.162
commit 831cb78a2a5e86fe705ef4e3095c7cbc587c6a57
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I6LQMS

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=831cb78a2a5e86fe705ef4e3095c7cbc587c6a57

--------------------------------

[ Upstream commit 10442994 ]

Right now we're never calling get_signal() from PF_IO_WORKER threads, but
in preparation for doing so, don't handle a fatal signal for them. The
workers have state they need to cleanup when exiting, so just return
instead of calling do_exit() on their behalf. The threads themselves will
detect a fatal signal and do proper shutdown.
Signed-off-by: NJens Axboe <axboe@kernel.dk>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NLi Lingfeng <lilingfeng3@huawei.com>
(cherry picked from commit e7553177)

kernel/signal.c

@@ -2760,6 +2760,14 @@ bool get_signal(struct ksignal *ksig)
 			do_coredump(&ksig->info);
 		}
 
+		/*
+		 * PF_IO_WORKER threads will catch and exit on fatal signals
+		 * themselves. They have cleanup that must be performed, so
+		 * we cannot call do_exit() on their behalf.
+		 */
+		if (current->flags & PF_IO_WORKER)
+			goto out;
+
 		/*
 		 * Death signals, no core dump.
 		 */
@@ -2767,7 +2775,7 @@ bool get_signal(struct ksignal *ksig)
 		/* NOTREACHED */
 	}
 	spin_unlock_irq(&sighand->siglock);
-
+out:
 	ksig->sig = signr;
 	return ksig->sig > 0;
 }