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 D2F934E06E6 for ; Wed, 16 Sep 2026 20:52:49 +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=1789591981; cv=none; b=NY3cvtVfVGw9jFXbIJeOZejGGpioZe+B/SYULwD5RNN9f/mu1QiiRp4fJe+Ofz9C+TS6QjHwHZ2dTeoSRdRZJqWP4agpl9C8meeDnsp6nQs3opOwFQbpj9hXmVTJoX/qvxqZ7M6xjt9RmPcZuNkwlcyezJHst58C1tADZkq7kUE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789591981; c=relaxed/simple; bh=y21hVAvo99Gq8YzT3jVXT4hbV/+9E08eHWxlhUz6xHM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=PMQT4saA67ha10zYIFGcGVswit9ARcWztUTkAjC/v4Ye1nhQ1o22kKn06dTzX084w0lWy3CrRM/Qya2RBFxV4pisXThydTvYeJKx6HhaQ1tr6y8KSx7nhfqHJ3x3m4WQRPKbpv9/MheNOWkLb5e5Iy7qiQZjjl0sdfVtsqJX0tc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=On8t7TIx; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="On8t7TIx" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BC0EB1F00893; Wed, 16 Sep 2026 20:52:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789591965; bh=OThOQxftxcCKbrcy7185G+G/2b8IB+FCbXeUevO/QLg=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=On8t7TIxmUApcisdPMciowUptJXk85ZvqkiMIDp0tg0K8CUoBeNCVvfwL5aX+kVEh QzMwguFjj7lIO2fN9ALOhGQg41hO54kawrnty2qOye0jsVA3IUprCqVPVX2g8cVgYa slRKlndx7zRcdHAK+ufXO/ac5N43BJxC0rsRHT5hfvJZ5XaiUGU8rTid4RNVIXl9ej 4e72XoWFrtZC/p8clamMTXOmzsGRUYh8jzcC6kHdrjpmYvFcXO2WKSDaN4DOM1zz3H GpgemXqG3gZh0zQDwo4dFeTsWSYw3CjUniFUFjDKjzAKt5R8POlJ6oX+fyVpMw1kPr tlPD81EBV2v9A== From: Sasha Levin To: stable@vger.kernel.org Cc: Jens Axboe , syzbot+2eb3d983669d3e49d4fa@syzkaller.appspotmail.com, Sasha Levin Subject: [PATCH 6.18.y] io_uring/rw: end write accounting from ->ki_complete Date: Wed, 16 Sep 2026 16:52:43 -0400 Message-ID: <20260916205243.2744997-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026091623-wrangle-flammable-47de@gregkh> References: <2026091623-wrangle-flammable-47de@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Jens Axboe [ Upstream commit 796aa0547557e63338657ed1c487906f9fac4c73 ] 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 [ adjusted io_complete_rw() context to preserve the existing IOCB_DIO_CALLER_COMP guard ] Signed-off-by: Sasha Levin --- io_uring/rw.c | 25 +++++++++++++------------ 1 file changed, 13 insertions(+), 12 deletions(-) diff --git a/io_uring/rw.c b/io_uring/rw.c index b78006228cc7f..3666ff3d2e421 100644 --- a/io_uring/rw.c +++ b/io_uring/rw.c @@ -532,20 +532,15 @@ 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. - */ -static void io_req_io_end(struct io_kiocb *req) +/* 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) { - io_req_end_write(req); + if (rw->kiocb.ki_flags & IOCB_WRITE) fsnotify_modify(req->file); - } else { + else fsnotify_access(req->file); - } } static void __io_complete_rw_common(struct io_kiocb *req, long res) @@ -586,7 +581,7 @@ void io_req_rw_complete(struct io_tw_req tw_req, io_tw_token_t tw) io_req_set_res(req, io_fixup_rw_res(req, res), 0); } - 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, req->cqe.res, NULL); @@ -600,6 +595,10 @@ 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); + if (!kiocb->dio_complete || !(kiocb->ki_flags & IOCB_DIO_CALLER_COMP)) { __io_complete_rw_common(req, res); io_req_set_res(req, io_fixup_rw_res(req, res), 0); @@ -675,10 +674,12 @@ static int kiocb_done(struct io_kiocb *req, ssize_t ret, __io_complete_rw_common(req, ret); /* - * Safe to call io_end from here as we're inline + * Safe to notify from here as we're inline * from the submission path. */ - io_req_io_end(req); + if (rw->kiocb.ki_flags & IOCB_WRITE) + io_req_end_write(req); + io_req_io_notify(req); if (sel) cflags = io_put_kbuf(req, ret, sel->buf_list); io_req_set_res(req, final_ret, cflags); -- 2.53.0