FAILED: patch "[PATCH] io_uring: don't touch sqd->thread off tw add" failed to apply to 6.12-stable tree

[<gregkh@linuxfoundation.org>]

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 <stable@vger.kernel.org>.

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 bd2703b42decebdcddf76e277ba76b4c4a142d73
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2025011256-extinct-expanse-d059@gregkh' --subject-prefix 'PATCH 6.12.y' HEAD^..

Possible dependencies:



thanks,

greg k-h

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

From bd2703b42decebdcddf76e277ba76b4c4a142d73 Mon Sep 17 00:00:00 2001
From: Pavel Begunkov <asml.silence@gmail.com>
Date: Fri, 10 Jan 2025 20:36:45 +0000
Subject: [PATCH] io_uring: don't touch sqd->thread off tw add

With IORING_SETUP_SQPOLL all requests are created by the SQPOLL task,
which means that req->task should always match sqd->thread. Since
accesses to sqd->thread should be separately protected, use req->task
in io_req_normal_work_add() instead.

Note, in the eyes of io_req_normal_work_add(), the SQPOLL task struct
is always pinned and alive, and sqd->thread can either be the task or
NULL. It's only problematic if the compiler decides to reload the value
after the null check, which is not so likely.

Cc: stable@vger.kernel.org
Cc: Bui Quang Minh <minhquangbui99@gmail.com>
Reported-by: lizetao <lizetao1@huawei.com>
Fixes: 78f9b61bd8e54 ("io_uring: wake SQPOLL task when task_work is added to an empty queue")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/1cbbe72cf32c45a8fee96026463024cd8564a7d7.1736541357.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index d3403c8216db..5eb119002099 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -1226,10 +1226,7 @@ static void io_req_normal_work_add(struct io_kiocb *req)
 
 	/* SQPOLL doesn't need the task_work added, it'll run it itself */
 	if (ctx->flags & IORING_SETUP_SQPOLL) {
-		struct io_sq_data *sqd = ctx->sq_data;
-
-		if (sqd->thread)
-			__set_notify_signal(sqd->thread);
+		__set_notify_signal(tctx->task);
 		return;
 	}