From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4099C3B14CF for ; Wed, 16 Sep 2026 15:29:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789572578; cv=none; b=PxprD7hlYEihLHWn1TkKv+QVSIp/XIxnCqRZUeJSKfsZXnJY4iiFh4BDsj7tYKxZr0Q4EnD6/Bi5R0hKKxDmd5NRvxOcBqL0yG4fYGHc5I+kZHkie8nYs9Zck6LN3hEw+EdkrCUO9AlaRvnwX0XFbWTDvawyKLo3aOiAl5qZqEU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789572578; c=relaxed/simple; bh=3KGv9q9COrjM8JM294vBCZqWeTIrmEB4yHoX9q0/t4A=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=lKFg5IRoDonrMgzThRxWd0CgavBORvql5UPyr0MHXYqS5HKo4R9CCfRuyLE08YdGfpRNIsJS4yMP5ZTC5aSheJX+QQ9PoUClSC6S28V++H1RAyji+xnFguRVz1yV9dOvoJcSSOw6izy6lwgnsszU/LE9oEHsJn6qMXG3eqOnGDA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Ehw1kriJ; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="Ehw1kriJ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E10851F000FF; Wed, 16 Sep 2026 15:29:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789572574; bh=zriep4d32caD+rKElt1Wf8MKSwuxrr3kkScEj+AwTHY=; h=Subject:To:Cc:From:Date; b=Ehw1kriJBZErUqvGqPbglJxvOQkOmfCmBaqDuVpWDGxUVLs+GbgOQdccRAw3fuePd fHd2Wylfg1gE0J8Fm9cGagugErR3QOo0mQPXa8+xVsxM/UVCC6F6POLHx0RG0ausD5 I+3bXNJ0QTd0CIG+Ner+MSOvW4Tvadm35ZcTef6I= Subject: FAILED: patch "[PATCH] io_uring/rw: end write accounting from ->ki_complete" failed to apply to 6.6-stable tree To: axboe@kernel.dk Cc: From: Date: Wed, 16 Sep 2026 16:20:24 +0100 Message-ID: <2026091624-delirium-hangout-abb2@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit 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 . 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 # git commit -s git send-email --to '' --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 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 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: syzbot+2eb3d983669d3e49d4fa@syzkaller.appspotmail.com Cc: stable@vger.kernel.org Fixes: b000145e9907 ("io_uring/rw: defer fsnotify calls to task context") Signed-off-by: Jens Axboe diff --git a/io_uring/rw.c b/io_uring/rw.c index 95106dd1d7eb..3e22f294bdf2 100644 --- a/io_uring/rw.c +++ b/io_uring/rw.c @@ -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;