linux-kernel - [PATCH 1/7] kernel: don't call do_exit() for PF_IO

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Message-Id: <20210326155128.1057078-2-axboe@kernel.dk>
Date:   Fri, 26 Mar 2021 09:51:14 -0600
From:   Jens Axboe <axboe@...nel.dk>
To:     io-uring@...r.kernel.org
Cc:     torvalds@...ux-foundation.org, ebiederm@...ssion.com,
        metze@...ba.org, oleg@...hat.com, linux-kernel@...r.kernel.org,
        Jens Axboe <axboe@...nel.dk>
Subject: [PATCH 1/7] kernel: don't call do_exit() for PF_IO_WORKER threads

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, and they don't do
coredumps, so just return instead of performing either a dump or calling
do_exit() on their behalf. The threads themselves will detect a fatal
signal and do proper shutdown.

Signed-off-by: Jens Axboe <axboe@...nel.dk>
---
 kernel/signal.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/kernel/signal.c b/kernel/signal.c
index f2a1b898da29..e3e1b8fbfe8a 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -2756,6 +2756,15 @@ bool get_signal(struct ksignal *ksig)
 		 */
 		current->flags |= PF_SIGNALED;
 
+		/*
+		 * 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. coredumps also
+		 * do not apply to them.
+		 */
+		if (current->flags & PF_IO_WORKER)
+			return false;
+
 		if (sig_kernel_coredump(signr)) {
 			if (print_fatal_signals)
 				print_fatal_signal(ksig->info.si_signo);
-- 
2.31.0