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 81b6d05ccad4f3d8a9dfb091fb46ad6978ee40e4 Mon Sep 17 00:00:00 2001
From: Pavel Begunkov asml.silence@gmail.com Date: Mon, 4 Jan 2021 20:36:35 +0000 Subject: [PATCH] io_uring: synchronise IOPOLL on task_submit fail
io_req_task_submit() might be called for IOPOLL, do the fail path under uring_lock to comply with IOPOLL synchronisation based solely on it.
Cc: stable@vger.kernel.org # 5.5+ 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 ca46f314640b..5be33fd8b6bc 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -2126,15 +2126,16 @@ static void io_req_task_cancel(struct callback_head *cb) static void __io_req_task_submit(struct io_kiocb *req) { struct io_ring_ctx *ctx = req->ctx; + bool fail;
- if (!__io_sq_thread_acquire_mm(ctx) && - !__io_sq_thread_acquire_files(ctx)) { - mutex_lock(&ctx->uring_lock); + fail = __io_sq_thread_acquire_mm(ctx) || + __io_sq_thread_acquire_files(ctx); + mutex_lock(&ctx->uring_lock); + if (!fail) __io_queue_sqe(req, NULL); - mutex_unlock(&ctx->uring_lock); - } else { + else __io_req_task_cancel(req, -EFAULT); - } + mutex_unlock(&ctx->uring_lock); }
static void io_req_task_submit(struct callback_head *cb)