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 5184B4E2F35 for ; Wed, 16 Sep 2026 23:42:08 +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=1789602130; cv=none; b=FtxNlWESfZENaVgi5W8z0GB08u2ZA2XrJHq0ofwt4LvJc2S8U5MpNmqNIITk4vW5o77ZBVnlldcBhoGP6TcAEzHc3R5Ep14JWRhx+aWsmzYKewa4eaEWQig8uEWSHdV0sT8bxS7sPa3EoR7aKO+P/4ezllCt8cR2HT3gUz+F69w= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789602130; c=relaxed/simple; bh=bVc6cGddBumjjTkoNkL4y+ji2p0TiWrnVv3ULKNTNCE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=AnQn7T/nEAY96sUQYdfhlQoEebVLEGQbYInKRrUNnV5kXqVjY2a9xm/SJcicza749hFWKUTkjD5hzNN53j78iCtu8lW37HwLN1iaTPJ3rshZfNKvcb5fYoLBkYTpfxWBJTYsxpJmmPSq49qaQBSGC8zUhxMnwEOyeDXutkv9yBs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=QUoHNW7D; 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="QUoHNW7D" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 663371F000FF; Wed, 16 Sep 2026 23:42:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789602128; bh=tQ2NBzkCTw9R/LweyRa0IyqPyFgOn98Fh5gfrFXVFSQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=QUoHNW7Dlxazfh2LRWM3IgCfjr8RudQbzWAYbnnV4NAKWRHXLJhkfXZf+EtCR50Aq O1Fs46m1mJwQRzEYCpOpe+bNiRr5LZiscfOK4oEyIMAigWRitu0ryQJ3mTYgnTD3KF VF1v/PMab/kQ0mhZM//o3f76ggcH37d9pFJeth4Pfjbt/rRFQDaubNhClJSv34vM8J HyJtFNBqevCkkLMErA0JUJaF7tAcMYKZo4kjflqyLBte1yTs4pqjHiE19C+xsdJrhS yrZJlwFNuGHEMszB+gZ6lL1V3VjoVtSh1OaQYyFNjMh1jTebCUyUzntB1/BrxMTfPS TnycWbDpVg0Lg== From: Sasha Levin To: stable@vger.kernel.org Cc: Jens Axboe , syzbot+2eb3d983669d3e49d4fa@syzkaller.appspotmail.com, Sasha Levin Subject: [PATCH 6.6.y] io_uring/rw: end write accounting from ->ki_complete Date: Wed, 16 Sep 2026 19:42:07 -0400 Message-ID: <20260916234207.3296009-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026091624-delirium-hangout-abb2@gregkh> References: <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=UTF-8 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 [ adapted completion cleanup to Linux 6.6’s existing direct-I/O and retry handling. ] Signed-off-by: Sasha Levin --- io_uring/rw.c | 32 +++++++++++++++----------------- 1 file changed, 15 insertions(+), 17 deletions(-) diff --git a/io_uring/rw.c b/io_uring/rw.c index f2ab967b95072..9c3932302cab9 100644 --- a/io_uring/rw.c +++ b/io_uring/rw.c @@ -244,20 +244,15 @@ 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 bool __io_complete_rw_common(struct io_kiocb *req, long res) @@ -265,11 +260,8 @@ static bool __io_complete_rw_common(struct io_kiocb *req, long res) if (unlikely(res != req->cqe.res)) { if ((res == -EAGAIN || res == -EOPNOTSUPP) && io_rw_should_reissue(req)) { - /* - * Reissue will start accounting again, finish the - * current cycle. - */ - io_req_io_end(req); + /* Notify for the current cycle before reissuing. */ + io_req_io_notify(req); req->flags |= REQ_F_REISSUE | REQ_F_PARTIAL_IO; return true; } @@ -304,7 +296,7 @@ void io_req_rw_complete(struct io_kiocb *req, struct io_tw_state *ts) 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)) { unsigned issue_flags = ts->locked ? 0 : IO_URING_F_UNLOCKED; @@ -319,6 +311,10 @@ 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)) { if (__io_complete_rw_common(req, res)) return; @@ -358,10 +354,12 @@ static int kiocb_done(struct io_kiocb *req, ssize_t ret, if (ret >= 0 && (rw->kiocb.ki_complete == io_complete_rw)) { if (!__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); io_req_set_res(req, final_ret, io_put_kbuf(req, issue_flags)); return IOU_OK; -- 2.53.0