The patch below does not apply to the 5.10-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From aec18a57edad562d620f7d19016de1fc0cc2208c Mon Sep 17 00:00:00 2001

From: Pavel Begunkov asml.silence@gmail.com Date: Thu, 4 Feb 2021 19:22:46 +0000 Subject: [PATCH] io_uring: drop mm/files between task_work_submit

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

diff --git a/fs/io_uring.c b/fs/io_uring.c index 5d3348d66f06..1f68105a41ed 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -2205,6 +2205,9 @@ static void __io_req_task_submit(struct io_kiocb *req) else __io_req_task_cancel(req, -EFAULT); mutex_unlock(&ctx->uring_lock); + + if (ctx->flags & IORING_SETUP_SQPOLL) + io_sq_thread_drop_mm_files(); }

static void io_req_task_submit(struct callback_head *cb)