On Sun, Jan 12, 2025 at 10:36:56AM +0100, gregkh@xxxxxxxxxxxxxxxxxxx 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@xxxxxxxxxxxxxxx>. > > 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@xxxxxxxxxxxxxxx>' --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@xxxxxxxxx> > 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@xxxxxxxxxxxxxxx > Cc: Bui Quang Minh <minhquangbui99@xxxxxxxxx> > Reported-by: lizetao <lizetao1@xxxxxxxxxx> > Fixes: 78f9b61bd8e54 ("io_uring: wake SQPOLL task when task_work is added to an empty queue") > Signed-off-by: Pavel Begunkov <asml.silence@xxxxxxxxx> > Link: https://lore.kernel.org/r/1cbbe72cf32c45a8fee96026463024cd8564a7d7.1736541357.git.asml.silence@xxxxxxxxx > Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> > > 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; > } Note, this breaks the build, it applies just fine, it's just that ->task is not a valid field here :( thanks, greg k-h
