[PATCH 5.10 16/54] io_uring: drop mm/files between task_work_submit

Greg Kroah-Hartman
2021-02-11T16:26:17Z

From: Pavel Begunkov <asml.silence@gmail.com>

[ Upstream commit aec18a57edad562d620f7d19016de1fc0cc2208c ]

Since SQPOLL task can be shared and so task_work entries can be a mix of
them, we need to drop mm and files before trying to issue next request.

Cc: stable@vger.kernel.org # 5.10+
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/io_uring.c | 3 +++
1 file changed, 3 insertions(+)

--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2084,6 +2084,9 @@ static void __io_req_task_submit(struct
else
__io_req_task_cancel(req, -EFAULT);
mutex_unlock(&ctx->uring_lock);
+
+ if (ctx->flags & IORING_SETUP_SQPOLL)
+ io_sq_thread_drop_mm();
}

static void io_req_task_submit(struct callback_head *cb)