[PATCH 0/3] stable-5.10 io_uring patches

[PATCH 0/3] stable-5.10 io_uring patches

[Pavel Begunkov]

Recently failed to apply io_uring stable-5.10 patches.

Dylan Yudaken (1):
  io_uring: always lock in io_apoll_task_func

Pavel Begunkov (2):
  io_uring: break out of iowq iopoll on teardown
  io_uring: break iopolling on signal

 io_uring/io-wq.c    | 10 ++++++++++
 io_uring/io-wq.h    |  1 +
 io_uring/io_uring.c |  9 ++++++++-
 3 files changed, 19 insertions(+), 1 deletion(-)

-- 
2.41.0

[PATCH 1/3] io_uring: always lock in io_apoll_task_func

[Pavel Begunkov]

From: Dylan Yudaken <dylany@meta.com>

[ upstream commit c06c6c5d276707e04cedbcc55625e984922118aa ]

This is required for the failure case (io_req_complete_failed) and is
missing.

The alternative would be to only lock in the failure path, however all of
the non-error paths in io_poll_check_events that do not do not return
IOU_POLL_NO_ACTION end up locking anyway. The only extraneous lock would
be for the multishot poll overflowing the CQE ring, however multishot poll
would probably benefit from being locked as it will allow completions to
be batched.

So it seems reasonable to lock always.

Signed-off-by: Dylan Yudaken <dylany@meta.com>
Link: https://lore.kernel.org/r/20221124093559.3780686-3-dylany@meta.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 io_uring/io_uring.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index dec8a6355f2a..ca484c4012b5 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -5571,6 +5571,7 @@ static void io_apoll_task_func(struct io_kiocb *req, bool *locked)
 	if (ret > 0)
 		return;
 
+	io_tw_lock(req->ctx, locked);
 	io_poll_remove_entries(req);
 	spin_lock(&ctx->completion_lock);
 	hash_del(&req->hash_node);
-- 
2.41.0

[PATCH 2/3] io_uring: break out of iowq iopoll on teardown

[Pavel Begunkov]

[ upstream commit 45500dc4e01c167ee063f3dcc22f51ced5b2b1e9 ]

io-wq will retry iopoll even when it failed with -EAGAIN. If that
races with task exit, which sets TIF_NOTIFY_SIGNAL for all its workers,
such workers might potentially infinitely spin retrying iopoll again and
again and each time failing on some allocation / waiting / etc. Don't
keep spinning if io-wq is dying.

Fixes: 561fb04a6a225 ("io_uring: replace workqueue usage with io-wq")
Cc: stable@vger.kernel.org
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 io_uring/io-wq.c    | 10 ++++++++++
 io_uring/io-wq.h    |  1 +
 io_uring/io_uring.c |  3 ++-
 3 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/io_uring/io-wq.c b/io_uring/io-wq.c
index 81485c1a9879..fe8594a0396c 100644
--- a/io_uring/io-wq.c
+++ b/io_uring/io-wq.c
@@ -176,6 +176,16 @@ static void io_worker_ref_put(struct io_wq *wq)
 		complete(&wq->worker_done);
 }
 
+bool io_wq_worker_stopped(void)
+{
+	struct io_worker *worker = current->pf_io_worker;
+
+	if (WARN_ON_ONCE(!io_wq_current_is_worker()))
+		return true;
+
+	return test_bit(IO_WQ_BIT_EXIT, &worker->wqe->wq->state);
+}
+
 static void io_worker_cancel_cb(struct io_worker *worker)
 {
 	struct io_wqe_acct *acct = io_wqe_get_acct(worker);
diff --git a/io_uring/io-wq.h b/io_uring/io-wq.h
index bf5c4c533760..48721cbd5f40 100644
--- a/io_uring/io-wq.h
+++ b/io_uring/io-wq.h
@@ -129,6 +129,7 @@ void io_wq_hash_work(struct io_wq_work *work, void *val);
 
 int io_wq_cpu_affinity(struct io_wq *wq, cpumask_var_t mask);
 int io_wq_max_workers(struct io_wq *wq, int *new_count);
+bool io_wq_worker_stopped(void);
 
 static inline bool io_wq_is_hashed(struct io_wq_work *work)
 {
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index ca484c4012b5..e5bef0a8e5ea 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -6898,7 +6898,8 @@ static void io_wq_submit_work(struct io_wq_work *work)
 			 */
 			if (ret != -EAGAIN || !(req->ctx->flags & IORING_SETUP_IOPOLL))
 				break;
-
+			if (io_wq_worker_stopped())
+				break;
 			/*
 			 * If REQ_F_NOWAIT is set, then don't wait or retry with
 			 * poll. -EAGAIN is final for that case.
-- 
2.41.0

[PATCH 3/3] io_uring: break iopolling on signal

[Pavel Begunkov]

[ upstream commit dc314886cb3d0e4ab2858003e8de2917f8a3ccbd ]

Don't keep spinning iopoll with a signal set. It'll eventually return
back, e.g. by virtue of need_resched(), but it's not a nice user
experience.

Cc: stable@vger.kernel.org
Fixes: def596e9557c9 ("io_uring: support for IO polling")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/eeba551e82cad12af30c3220125eb6cb244cc94c.1691594339.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 io_uring/io_uring.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index e5bef0a8e5ea..800b5cc385af 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -2665,6 +2665,11 @@ static int io_iopoll_check(struct io_ring_ctx *ctx, long min)
 				break;
 		}
 		ret = io_do_iopoll(ctx, &nr_events, min);
+
+		if (task_sigpending(current)) {
+			ret = -EINTR;
+			goto out;
+		}
 	} while (!ret && nr_events < min && !need_resched());
 out:
 	mutex_unlock(&ctx->uring_lock);
-- 
2.41.0