FAILED: patch "[PATCH] io_uring/kbuf: propagate BUF_MORE through early buffer commit" failed to apply to 6.12-stable tree

PATCH [email protected] 2 participants 3 messages Mar 20 – Mar 21

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[email protected]

author maintainer

2026-03-20 17:34 UTC #0 lore raw

The patch below does not apply to the 6.12-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-6.12.y
git checkout FETCH_HEAD
git cherry-pick -x 418eab7a6f3c002d8e64d6e95ec27118017019af
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026032021-amused-playable-2e81@gregkh' --subject-prefix 'PATCH 6.12.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

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

From 418eab7a6f3c002d8e64d6e95ec27118017019af Mon Sep 17 00:00:00 2001
From: Jens Axboe <[email protected]>
Date: Thu, 19 Mar 2026 14:29:20 -0600
Subject: [PATCH] io_uring/kbuf: propagate BUF_MORE through early buffer commit
path

When io_should_commit() returns true (eg for non-pollable files), buffer commit happens at buffer selection time and sel->buf_list is set to NULL. When __io_put_kbufs() generates CQE flags at completion time, it calls __io_put_kbuf_ring() which finds a NULL buffer_list and hence cannot determine whether the buffer was consumed or not. This means that IORING_CQE_F_BUF_MORE is never set for non-pollable input with incrementally consumed buffers.

Likewise for io_buffers_select(), which always commits upfront and discards the return value of io_kbuf_commit().

Add REQ_F_BUF_MORE to store the result of io_kbuf_commit() during early commit. Then __io_put_kbuf_ring() can check this flag and set IORING_F_BUF_MORE accordingy.

Reported-by Martin Michaelis <[email protected]>

Cc [email protected]

Fixes ae98dbf43d75 ("io_uring/kbuf: add support for incremental buffer consumption")

Link https://github.com/axboe/liburing/issues/1553

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

include/linux/io_uring_types.h +3 -0

index dd1420bfcb73..214fdbd49052 100644
@@ -541,6 +541,7 @@ enum {
 	REQ_F_BL_NO_RECYCLE_BIT,
 	REQ_F_BUFFERS_COMMIT_BIT,
 	REQ_F_BUF_NODE_BIT,
+	REQ_F_BUF_MORE_BIT,
 	REQ_F_HAS_METADATA_BIT,
 	REQ_F_IMPORT_BUFFER_BIT,
 	REQ_F_SQE_COPIED_BIT,

@@ -626,6 +627,8 @@ enum {
 	REQ_F_BUFFERS_COMMIT	= IO_REQ_FLAG(REQ_F_BUFFERS_COMMIT_BIT),
 	/* buf node is valid */
 	REQ_F_BUF_NODE		= IO_REQ_FLAG(REQ_F_BUF_NODE_BIT),
+	/* incremental buffer consumption, more space available */
+	REQ_F_BUF_MORE		= IO_REQ_FLAG(REQ_F_BUF_MORE_BIT),
 	/* request has read/write metadata assigned */
 	REQ_F_HAS_METADATA	= IO_REQ_FLAG(REQ_F_HAS_METADATA_BIT),
 	/*

io_uring/kbuf.c +7 -3

index a4cb6752b7aa..f72f38d22d2b 100644
@@ -216,7 +216,8 @@ static struct io_br_sel io_ring_buffer_select(struct io_kiocb *req, size_t *len,
 	sel.addr = u64_to_user_ptr(READ_ONCE(buf->addr));
 
 	if (io_should_commit(req, issue_flags)) {
-		io_kbuf_commit(req, sel.buf_list, *len, 1);
+		if (!io_kbuf_commit(req, sel.buf_list, *len, 1))
+			req->flags |= REQ_F_BUF_MORE;
 		sel.buf_list = NULL;
 	}
 	return sel;

@@ -349,7 +350,8 @@ int io_buffers_select(struct io_kiocb *req, struct buf_sel_arg *arg,
 		 */
 		if (ret > 0) {
 			req->flags |= REQ_F_BUFFERS_COMMIT | REQ_F_BL_NO_RECYCLE;
-			io_kbuf_commit(req, sel->buf_list, arg->out_len, ret);
+			if (!io_kbuf_commit(req, sel->buf_list, arg->out_len, ret))
+				req->flags |= REQ_F_BUF_MORE;
 		}
 	} else {
 		ret = io_provided_buffers_select(req, &arg->out_len, sel->buf_list, arg->iovs);

@@ -395,8 +397,10 @@ static inline bool __io_put_kbuf_ring(struct io_kiocb *req,
 
 	if (bl)
 		ret = io_kbuf_commit(req, bl, len, nr);
+	if (ret && (req->flags & REQ_F_BUF_MORE))
+		ret = false;
 
-	req->flags &= ~REQ_F_BUFFER_RING;
+	req->flags &= ~(REQ_F_BUFFER_RING | REQ_F_BUF_MORE);
 	return ret;
 }

Jens Axboe

maintainer

2026-03-20 18:29 UTC #1 lore raw

Quoted 5 lines · On 3/20/26 11:34 AM, [email protected] wrote:

The patch below does not apply to the 6.12-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]>.

Here's a tested version for 6.12-stable.

Signature · 1 line

Jens Axboe

From 53bf975f094d3d1f2e499e86bd5af7a9b4b08a4d Mon Sep 17 00:00:00 2001
From: Jens Axboe <[email protected]>
Date: Thu, 19 Mar 2026 14:29:20 -0600
Subject: [PATCH] io_uring/kbuf: propagate BUF_MORE through early buffer commit
path

Commit 418eab7a6f3c002d8e64d6e95ec27118017019af upstream.

Likewise for io_buffers_select(), which always commits upfront and discards the return value of io_kbuf_commit().

Add REQ_F_BUF_MORE to store the result of io_kbuf_commit() during early commit. Then __io_put_kbuf_ring() can check this flag and set IORING_F_BUF_MORE accordingy.

Reported-by Martin Michaelis <[email protected]>

Cc [email protected]

Fixes ae98dbf43d75 ("io_uring/kbuf: add support for incremental buffer consumption")

Link https://github.com/axboe/liburing/issues/1553

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

---
 include/linux/io_uring_types.h | 3 +++
 io_uring/kbuf.c                | 6 ++++--
 io_uring/kbuf.h                | 4 +++-
 3 files changed, 10 insertions(+), 3 deletions(-)

include/linux/io_uring_types.h +3 -0

index f18f50d39598..9c61e3b96628 100644
@@ -467,6 +467,7 @@ enum {
 	REQ_F_BL_EMPTY_BIT,
 	REQ_F_BL_NO_RECYCLE_BIT,
 	REQ_F_BUFFERS_COMMIT_BIT,
+	REQ_F_BUF_MORE_BIT,
 
 	/* not a real bit, just to check we're not overflowing the space */
 	__REQ_F_LAST_BIT,

@@ -547,6 +548,8 @@ enum {
 	REQ_F_BL_NO_RECYCLE	= IO_REQ_FLAG(REQ_F_BL_NO_RECYCLE_BIT),
 	/* buffer ring head needs incrementing on put */
 	REQ_F_BUFFERS_COMMIT	= IO_REQ_FLAG(REQ_F_BUFFERS_COMMIT_BIT),
+	/* incremental buffer consumption, more space available */
+	REQ_F_BUF_MORE		= IO_REQ_FLAG(REQ_F_BUF_MORE_BIT),
 };
 
 typedef void (*io_req_tw_func_t)(struct io_kiocb *req, struct io_tw_state *ts);

io_uring/kbuf.c +4 -2

index 25597f0629f3..590973c47cd3 100644
@@ -175,7 +175,8 @@ static void __user *io_ring_buffer_select(struct io_kiocb *req, size_t *len,
 		 * the transfer completes (or if we get -EAGAIN and must poll of
 		 * retry).
 		 */
-		io_kbuf_commit(req, bl, *len, 1);
+		if (!io_kbuf_commit(req, bl, *len, 1))
+			req->flags |= REQ_F_BUF_MORE;
 		req->buf_list = NULL;
 	}
 	return ret;

@@ -321,7 +322,8 @@ int io_buffers_select(struct io_kiocb *req, struct buf_sel_arg *arg,
 		 */
 		if (ret > 0) {
 			req->flags |= REQ_F_BUFFERS_COMMIT | REQ_F_BL_NO_RECYCLE;
-			io_kbuf_commit(req, bl, arg->out_len, ret);
+			if (!io_kbuf_commit(req, bl, arg->out_len, ret))
+				req->flags |= REQ_F_BUF_MORE;
 		}
 	} else {
 		ret = io_provided_buffers_select(req, &arg->out_len, bl, arg->iovs);

io_uring/kbuf.h +3 -1

index a3ad8aea45c8..903800b20ff3 100644
@@ -165,7 +165,9 @@ static inline bool __io_put_kbuf_ring(struct io_kiocb *req, int len, int nr)
 		ret = io_kbuf_commit(req, bl, len, nr);
 		req->buf_index = bl->bgid;
 	}
-	req->flags &= ~REQ_F_BUFFER_RING;
+	if (ret && (req->flags & REQ_F_BUF_MORE))
+		ret = false;
+	req->flags &= ~(REQ_F_BUFFER_RING | REQ_F_BUF_MORE);
 	return ret;
 }

Signature · 1 line

2.53.0

Greg KH

author maintainer

2026-03-21 06:19 UTC #2 lore raw

Quoted 8 lines · Jens Axboe

Quoted 5 lines · On 3/20/26 11:34 AM, [email protected] wrote:
The patch below does not apply to the 6.12-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]>.
Here's a tested version for 6.12-stable.

Now queued up, thanks.

greg k-h