linux-kernel - [PATCH 5.15 171/207] io-wq: dont retry task_work creation failure on fatal conditions

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Message-Id: <20211206145616.188238474@linuxfoundation.org>
Date:   Mon,  6 Dec 2021 15:57:05 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Florian Fischer <florian.fl.fischer@....de>,
        Jens Axboe <axboe@...nel.dk>, Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.15 171/207] io-wq: dont retry task_work creation failure on fatal conditions

From: Jens Axboe <axboe@...nel.dk>

[ Upstream commit a226abcd5d427fe9d42efc442818a4a1821e2664 ]

We don't want to be retrying task_work creation failure if there's
an actual signal pending for the parent task. If we do, then we can
enter an infinite loop of perpetually retrying and each retry failing
with -ERESTARTNOINTR because a signal is pending.

Fixes: 3146cba99aa2 ("io-wq: make worker creation resilient against signals")
Reported-by: Florian Fischer <florian.fl.fischer@....de>
Link: https://lore.kernel.org/io-uring/20211202165606.mqryio4yzubl7ms5@pasture/
Tested-by: Florian Fischer <florian.fl.fischer@....de>
Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/io-wq.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/fs/io-wq.c b/fs/io-wq.c
index 8c61315657546..e8f77903d7757 100644
--- a/fs/io-wq.c
+++ b/fs/io-wq.c
@@ -711,6 +711,13 @@ static bool io_wq_work_match_all(struct io_wq_work *work, void *data)
 
 static inline bool io_should_retry_thread(long err)
 {
+	/*
+	 * Prevent perpetual task_work retry, if the task (or its group) is
+	 * exiting.
+	 */
+	if (fatal_signal_pending(current))
+		return false;
+
 	switch (err) {
 	case -EAGAIN:
 	case -ERESTARTSYS:
-- 
2.33.0