FAILED: patch "[PATCH] io_uring/rw: end write accounting from ->ki_complete" failed to apply to 6.6-stable tree

PATCH New [email protected] 2 participants 2 messages Sep 16

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Stable branch io_uring

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[email protected]

author maintainer

2026-09-16 15:29 UTC #0 lore raw

The patch below does not apply to the 6.6-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-6.6.y
git checkout FETCH_HEAD
git cherry-pick -x 796aa0547557e63338657ed1c487906f9fac4c73
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026091624-delirium-hangout-abb2@gregkh' --subject-prefix 'PATCH 6.6.y' 'HEAD^..'

Possible dependencies:

thanks,

greg k-h

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

From 796aa0547557e63338657ed1c487906f9fac4c73 Mon Sep 17 00:00:00 2001
From: Jens Axboe <[email protected]>
Date: Tue, 8 Sep 2026 17:53:20 -0600
Subject: [PATCH] io_uring/rw: end write accounting from ->ki_complete

Commit b000145e9907 moved both the fsnotify calls and the write accounting out of the kiocb completion handler and into the io_req_rw_complete() task_work. However, only the fsnotify part actually needed to move as it may sleep. Ending the write accounting is just a percpu_up_read() on the superblock writers sem.

Deferring it is a problem, because it makes dropping SB_FREEZE_WRITE protection depend on the ring owner getting to running task_work. But the task may be blocked in freeze_super(), causing it to never get to that:

task io-wq worker
--------------------------------------------------------------
io_write()
io_kiocb_start_write() (takes sb_writers, hidden from
lockdep by __sb_writers_release)
write_iter() -> -EIOCBQUEUED
ioctl(FS_IOC_SHUTDOWN)
bdev_freeze()
freeze_super()
percpu_down_write() <- waits for the reader above
io_write()
kiocb_start_write()
percpu_down_read() <- queued
behind the writer
<bio completes>
io_complete_rw()
queues io_req_rw_complete() <- never runs, task is in D state

End the write from io_complete_rw() instead, and leave only the fsnotify calls in task_work.

Reported-by [email protected]

Cc [email protected]

Fixes b000145e9907 ("io_uring/rw: defer fsnotify calls to task context")

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

io_uring/rw.c +19 ~~-10~~

index 95106dd1d7eb..3e22f294bdf2 100644
@@ -517,20 +517,25 @@ static void io_req_end_write(struct io_kiocb *req)
 	}
 }
 
-/*
- * Trigger the notifications after having done some IO, and finish the write
- * accounting, if any.
- */
+/* Trigger the notifications after having done some IO. */
+static void io_req_io_notify(struct io_kiocb *req)
+{
+	struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
+
+	if (rw->kiocb.ki_flags & IOCB_WRITE)
+		fsnotify_modify(req->file);
+	else
+		fsnotify_access(req->file);
+}
+
+/* Finish write accounting and notify, for inline completions only. */
 static void io_req_io_end(struct io_kiocb *req)
 {
 	struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
 
-	if (rw->kiocb.ki_flags & IOCB_WRITE) {
+	if (rw->kiocb.ki_flags & IOCB_WRITE)
 		io_req_end_write(req);
-		fsnotify_modify(req->file);
-	} else {
-		fsnotify_access(req->file);
-	}
+	io_req_io_notify(req);
 }
 
 static void __io_complete_rw_common(struct io_kiocb *req, long res)

@@ -563,7 +568,7 @@ void io_req_rw_complete(struct io_tw_req tw_req, io_tw_token_t tw)
 {
 	struct io_kiocb *req = tw_req.req;
 
-	io_req_io_end(req);
+	io_req_io_notify(req);
 
 	if (req->flags & (REQ_F_BUFFER_SELECTED|REQ_F_BUFFER_RING))
 		req->cqe.flags |= io_put_kbuf(req, max(req->cqe.res, 0), NULL);

@@ -577,6 +582,10 @@ static void io_complete_rw(struct kiocb *kiocb, long res)
 	struct io_rw *rw = container_of(kiocb, struct io_rw, kiocb);
 	struct io_kiocb *req = cmd_to_io_kiocb(rw);
 
+	/* ring owner may block in freeze_super() before task_work runs */
+	if (kiocb->ki_flags & IOCB_WRITE)
+		io_req_end_write(req);
+
 	__io_complete_rw_common(req, res);
 	io_req_set_res(req, io_fixup_rw_res(req, res), 0);
 	req->io_task_work.func = io_req_rw_complete;

Sasha Levin

maintainer

2026-09-16 23:42 UTC #1 lore raw

PATCH 1/1 io_uring/rw: end write accounting from ->ki_complete

From: Jens Axboe <[email protected]>

[ Upstream commit 796aa0547557e63338657ed1c487906f9fac4c73 ]

End the write from io_complete_rw() instead, and leave only the fsnotify calls in task_work.

Reported-by [email protected]

Cc [email protected]

Fixes b000145e9907 ("io_uring/rw: defer fsnotify calls to task context")

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

[ adapted completion cleanup to Linux 6.6’s existing direct-I/O and retry handling. ]

Signed-off-by Sasha Levin <[email protected]>

---
 io_uring/rw.c | 32 +++++++++++++++-----------------
 1 file changed, 15 insertions(+), 17 deletions(-)

io_uring/rw.c +15 ~~-17~~

index f2ab967b95072..9c3932302cab9 100644
@@ -244,20 +244,15 @@ static void io_req_end_write(struct io_kiocb *req)
 	}
 }
 
-/*
- * Trigger the notifications after having done some IO, and finish the write
- * accounting, if any.
- */
-static void io_req_io_end(struct io_kiocb *req)
+/* Trigger the notifications after having done some IO. */
+static void io_req_io_notify(struct io_kiocb *req)
 {
 	struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
 
-	if (rw->kiocb.ki_flags & IOCB_WRITE) {
-		io_req_end_write(req);
+	if (rw->kiocb.ki_flags & IOCB_WRITE)
 		fsnotify_modify(req->file);
-	} else {
+	else
 		fsnotify_access(req->file);
-	}
 }
 
 static bool __io_complete_rw_common(struct io_kiocb *req, long res)

@@ -265,11 +260,8 @@ static bool __io_complete_rw_common(struct io_kiocb *req, long res)
 	if (unlikely(res != req->cqe.res)) {
 		if ((res == -EAGAIN || res == -EOPNOTSUPP) &&
 		    io_rw_should_reissue(req)) {
-			/*
-			 * Reissue will start accounting again, finish the
-			 * current cycle.
-			 */
-			io_req_io_end(req);
+			/* Notify for the current cycle before reissuing. */
+			io_req_io_notify(req);
 			req->flags |= REQ_F_REISSUE | REQ_F_PARTIAL_IO;
 			return true;
 		}

@@ -304,7 +296,7 @@ void io_req_rw_complete(struct io_kiocb *req, struct io_tw_state *ts)
 		io_req_set_res(req, io_fixup_rw_res(req, res), 0);
 	}
 
-	io_req_io_end(req);
+	io_req_io_notify(req);
 
 	if (req->flags & (REQ_F_BUFFER_SELECTED|REQ_F_BUFFER_RING)) {
 		unsigned issue_flags = ts->locked ? 0 : IO_URING_F_UNLOCKED;

@@ -319,6 +311,10 @@ static void io_complete_rw(struct kiocb *kiocb, long res)
 	struct io_rw *rw = container_of(kiocb, struct io_rw, kiocb);
 	struct io_kiocb *req = cmd_to_io_kiocb(rw);
 
+	/* ring owner may block in freeze_super() before task_work runs */
+	if (kiocb->ki_flags & IOCB_WRITE)
+		io_req_end_write(req);
+
 	if (!kiocb->dio_complete || !(kiocb->ki_flags & IOCB_DIO_CALLER_COMP)) {
 		if (__io_complete_rw_common(req, res))
 			return;

@@ -358,10 +354,12 @@ static int kiocb_done(struct io_kiocb *req, ssize_t ret,
 	if (ret >= 0 && (rw->kiocb.ki_complete == io_complete_rw)) {
 		if (!__io_complete_rw_common(req, ret)) {
 			/*
-			 * Safe to call io_end from here as we're inline
+			 * Safe to notify from here as we're inline
 			 * from the submission path.
 			 */
-			io_req_io_end(req);
+			if (rw->kiocb.ki_flags & IOCB_WRITE)
+				io_req_end_write(req);
+			io_req_io_notify(req);
 			io_req_set_res(req, final_ret,
 				       io_put_kbuf(req, issue_flags));
 			return IOU_OK;

Signature · 1 line

2.53.0