On Sun, Jan 12, 2025 at 10:36:56AM +0100, gregkh@linuxfoundation.org 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 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/1cbbe72cf32c45a8fee96026463024cd8564a7d7.173654135... 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);
Note, this breaks the build, it applies just fine, it's just that ->task is not a valid field here :(
thanks,
greg k-h