io-wq: don't retry task_work creation failure on fatal conditions

BugLink: https://bugs.launchpad.net/bugs/1953731
[ 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@fau.de>
Link: https://lore.kernel.org/io-uring/20211202165606.mqryio4yzubl7ms5@pasture/
Tested-by: Florian Fischer <florian.fl.fischer@fau.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>

diff --git a/fs/io-wq.c b/fs/io-wq.c
index 8c6131565754664f18704f24c1954f108342f1af..e8f77903d7757d97ce4a41a3700d5d99781da168 100644 (file)
--- 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: