FAILED: patch "[PATCH] io_uring: disable io-wq execution of multishot NOWAIT" failed to apply to 6.8-stable tree

PATCH [email protected] 2 participants 4 messages Apr 8, 2024 – Apr 15, 2024

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Stable branch io_uring

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[email protected]

author maintainer

2024-04-08 09:11 UTC #0 lore raw

The patch below does not apply to the 6.8-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 <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.8.y
git checkout FETCH_HEAD
git cherry-pick -x bee1d5becdf5bf23d4ca0cd9c6b60bdf3c61d72b
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2024040826-handbrake-five-e04e@gregkh' --subject-prefix 'PATCH 6.8.y' HEAD^..

Possible dependencies:

bee1d5becdf5 ("io_uring: disable io-wq execution of multishot NOWAIT requests") e0e4ab52d170 ("io_uring: refactor DEFER_TASKRUN multishot checks") 3a96378e22cc ("io_uring: fix mshot io-wq checks")
eb18c29dd2a3 ("io_uring/net: move recv/recvmsg flags out of retry loop")

thanks,

greg k-h

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

From bee1d5becdf5bf23d4ca0cd9c6b60bdf3c61d72b Mon Sep 17 00:00:00 2001
From: Jens Axboe <[email protected]>
Date: Mon, 1 Apr 2024 11:30:06 -0600
Subject: [PATCH] io_uring: disable io-wq execution of multishot NOWAIT
requests

Do the same check for direct io-wq execution for multishot requests that commit 2a975d426c82 did for the inline execution, and disable multishot mode (and revert to single shot) if the file type doesn't support NOWAIT, and isn't opened in O_NONBLOCK mode. For multishot to work properly, it's a requirement that nonblocking read attempts can be done.

Cc [email protected]

Signed-off-by Jens Axboe <[email protected]>

io_uring/io_uring.c +9 -4

index 5d4b448fdc50..8baf8afb79c2 100644
@@ -1982,10 +1982,15 @@ void io_wq_submit_work(struct io_wq_work *work)
 		err = -EBADFD;
 		if (!io_file_can_poll(req))
 			goto fail;
-		err = -ECANCELED;
-		if (io_arm_poll_handler(req, issue_flags) != IO_APOLL_OK)
-			goto fail;
-		return;
+		if (req->file->f_flags & O_NONBLOCK ||
+		    req->file->f_mode & FMODE_NOWAIT) {
+			err = -ECANCELED;
+			if (io_arm_poll_handler(req, issue_flags) != IO_APOLL_OK)
+				goto fail;
+			return;
+		} else {
+			req->flags &= ~REQ_F_APOLL_MULTISHOT;
+		}
 	}
 
 	if (req->flags & REQ_F_FORCE_ASYNC) {

Jens Axboe

maintainer

2024-04-11 16:28 UTC #1 lore raw

Quoted 6 lines · On 4/8/24 3:11 AM, [email protected] wrote:

The patch below does not apply to the 6.8-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 <[email protected]>.

Quoted 8 lines

To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.8.y
git checkout FETCH_HEAD
git cherry-pick -x bee1d5becdf5bf23d4ca0cd9c6b60bdf3c61d72b
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2024040826-handbrake-five-e04e@gregkh' --subject-prefix 'PATCH 6.8.y' HEAD^..

Here's the dependency and the patch itself backported, please add for 6.8. Thanks!

Signature · 1 line

Jens Axboe

From 5984bb9e2b72455e8e5a1925edde3079c9f949be Mon Sep 17 00:00:00 2001
From: Jens Axboe <[email protected]>
Date: Mon, 1 Apr 2024 11:30:06 -0600
Subject: [PATCH 2/2] io_uring: disable io-wq execution of multishot NOWAIT
requests

Commit bee1d5becdf5bf23d4ca0cd9c6b60bdf3c61d72b upstream.

Cc [email protected]

Signed-off-by Jens Axboe <[email protected]>

---
 io_uring/io_uring.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

io_uring/io_uring.c +9 -4

index 6fdcb5e07807..1a9f96ed259e 100644
@@ -1964,10 +1964,15 @@ void io_wq_submit_work(struct io_wq_work *work)
 		err = -EBADFD;
 		if (!file_can_poll(req->file))
 			goto fail;
-		err = -ECANCELED;
-		if (io_arm_poll_handler(req, issue_flags) != IO_APOLL_OK)
-			goto fail;
-		return;
+		if (req->file->f_flags & O_NONBLOCK ||
+		    req->file->f_mode & FMODE_NOWAIT) {
+			err = -ECANCELED;
+			if (io_arm_poll_handler(req, issue_flags) != IO_APOLL_OK)
+				goto fail;
+			return;
+		} else {
+			req->flags &= ~REQ_F_APOLL_MULTISHOT;
+		}
 	}
 
 	if (req->flags & REQ_F_FORCE_ASYNC) {

Signature · 1 line

2.43.0

From 6fa8da25be5ad285fae51584ce1d461fec42bd94 Mon Sep 17 00:00:00 2001
From: Pavel Begunkov <[email protected]>
Date: Fri, 8 Mar 2024 13:55:57 +0000
Subject: [PATCH 1/2] io_uring: refactor DEFER_TASKRUN multishot checks

Commit e0e4ab52d17096d96c21a6805ccd424b283c3c6d upstream.

We disallow DEFER_TASKRUN multishots from running by io-wq, which is checked by individual opcodes in the issue path. We can consolidate all it in io_wq_submit_work() at the same time moving the checks out of the hot path.

Signed-off-by Pavel Begunkov <[email protected]>

Link https://lore.kernel.org/r/e492f0f11588bb5aa11d7d24e6f53b7c7628afdb.1709905727.git.asml.silence@gmail.com open here

Signed-off-by Jens Axboe <[email protected]>

---
 io_uring/io_uring.c | 20 ++++++++++++++++++++
 io_uring/net.c      | 21 ---------------------
 io_uring/rw.c       |  2 --
 3 files changed, 20 insertions(+), 23 deletions(-)

io_uring/io_uring.c +20 -0

index 572effd0af53..6fdcb5e07807 100644
@@ -949,6 +949,8 @@ bool io_fill_cqe_req_aux(struct io_kiocb *req, bool defer, s32 res, u32 cflags)
 	u64 user_data = req->cqe.user_data;
 	struct io_uring_cqe *cqe;
 
+	lockdep_assert(!io_wq_current_is_worker());
+
 	if (!defer)
 		return __io_post_aux_cqe(ctx, user_data, res, cflags, false);

@@ -1950,6 +1952,24 @@ void io_wq_submit_work(struct io_wq_work *work)
 		goto fail;
 	}
 
+	/*
+	 * If DEFER_TASKRUN is set, it's only allowed to post CQEs from the
+	 * submitter task context. Final request completions are handed to the
+	 * right context, however this is not the case of auxiliary CQEs,
+	 * which is the main mean of operation for multishot requests.
+	 * Don't allow any multishot execution from io-wq. It's more restrictive
+	 * than necessary and also cleaner.
+	 */
+	if (req->flags & REQ_F_APOLL_MULTISHOT) {
+		err = -EBADFD;
+		if (!file_can_poll(req->file))
+			goto fail;
+		err = -ECANCELED;
+		if (io_arm_poll_handler(req, issue_flags) != IO_APOLL_OK)
+			goto fail;
+		return;
+	}
+
 	if (req->flags & REQ_F_FORCE_ASYNC) {
 		bool opcode_poll = def->pollin || def->pollout;

io_uring/net.c +0 ~~-21~~

index 5a4001139e28..65947b9afc71 100644
@@ -78,19 +78,6 @@ struct io_sr_msg {
  */
 #define MULTISHOT_MAX_RETRY	32
 
-static inline bool io_check_multishot(struct io_kiocb *req,
-				      unsigned int issue_flags)
-{
-	/*
-	 * When ->locked_cq is set we only allow to post CQEs from the original
-	 * task context. Usual request completions will be handled in other
-	 * generic paths but multipoll may decide to post extra cqes.
-	 */
-	return !(issue_flags & IO_URING_F_IOWQ) ||
-		!(req->flags & REQ_F_APOLL_MULTISHOT) ||
-		!req->ctx->task_complete;
-}
-
 int io_shutdown_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 {
 	struct io_shutdown *shutdown = io_kiocb_to_cmd(req, struct io_shutdown);

@@ -837,9 +824,6 @@ int io_recvmsg(struct io_kiocb *req, unsigned int issue_flags)
 	    (sr->flags & IORING_RECVSEND_POLL_FIRST))
 		return io_setup_async_msg(req, kmsg, issue_flags);
 
-	if (!io_check_multishot(req, issue_flags))
-		return io_setup_async_msg(req, kmsg, issue_flags);
-
 retry_multishot:
 	if (io_do_buffer_select(req)) {
 		void __user *buf;

@@ -935,9 +919,6 @@ int io_recv(struct io_kiocb *req, unsigned int issue_flags)
 	    (sr->flags & IORING_RECVSEND_POLL_FIRST))
 		return -EAGAIN;
 
-	if (!io_check_multishot(req, issue_flags))
-		return -EAGAIN;
-
 	sock = sock_from_file(req->file);
 	if (unlikely(!sock))
 		return -ENOTSOCK;

@@ -1386,8 +1367,6 @@ int io_accept(struct io_kiocb *req, unsigned int issue_flags)
 	struct file *file;
 	int ret, fd;
 
-	if (!io_check_multishot(req, issue_flags))
-		return -EAGAIN;
 retry:
 	if (!fixed) {
 		fd = __get_unused_fd_flags(accept->flags, accept->nofile);

io_uring/rw.c +0 -2

index dd6fe3b328f4..c3c154790e45 100644
@@ -932,8 +932,6 @@ int io_read_mshot(struct io_kiocb *req, unsigned int issue_flags)
 	 */
 	if (!file_can_poll(req->file))
 		return -EBADFD;
-	if (issue_flags & IO_URING_F_IOWQ)
-		return -EAGAIN;
 
 	ret = __io_read(req, issue_flags);

Signature · 1 line

2.43.0

Greg KH

author maintainer

2024-04-15 10:49 UTC #2 lore raw

Quoted 16 lines · Jens Axboe

Quoted 6 lines · On 4/8/24 3:11 AM, [email protected] wrote:
The patch below does not apply to the 6.8-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 <[email protected]>.
Quoted 8 lines
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.8.y
git checkout FETCH_HEAD
git cherry-pick -x bee1d5becdf5bf23d4ca0cd9c6b60bdf3c61d72b
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2024040826-handbrake-five-e04e@gregkh' --subject-prefix 'PATCH 6.8.y' HEAD^..

Quoted 2 lines

Here's the dependency and the patch itself backported, please add for 6.8. Thanks!

Both now queued up, thanks!

greg k-h

Jens Axboe

maintainer

2024-04-15 14:23 UTC #3 lore raw

Quoted 17 lines · Greg KH

Quoted 16 lines · Jens Axboe
Quoted 14 lines · On 4/8/24 3:11 AM, [email protected] wrote:
The patch below does not apply to the 6.8-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 <[email protected]>.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.8.y
git checkout FETCH_HEAD
git cherry-pick -x bee1d5becdf5bf23d4ca0cd9c6b60bdf3c61d72b
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2024040826-handbrake-five-e04e@gregkh' --subject-prefix 'PATCH 6.8.y' HEAD^..

Quoted 4 lines

Quoted 2 lines
Here's the dependency and the patch itself backported, please add for 6.8. Thanks!
Both now queued up, thanks!

Thanks Greg!

Signature · 1 line

Jens Axboe