From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 61869BA49 for ; Tue, 7 Mar 2023 18:32:10 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D404EC433D2; Tue, 7 Mar 2023 18:32:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1678213930; bh=YTUJLvMddYqETv4VWZZPM9evhw7Q3EgGxqYOUlciBl0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=vAmLGzJJxQyAAX8LwmrbPf9Y3jgWLetZncpsYdr+ryBRckKtPTQ26KEblplP49FoD wHf9SThKMet1lWuoYR3aKsNIodmW6fOK9ZBoEeAySVWZE/gr4MEGygnyJ8yE/aSPpL 0lXq7e64zr+MPxpc4dc0xDKGQ34ejvFvHll92wpo= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Heming Zhao , Joseph Qi , Xiaoguang Wang , Jens Axboe Subject: [PATCH 6.1 664/885] io_uring: fix fget leak when fs dont support nowait buffered read Date: Tue, 7 Mar 2023 17:59:58 +0100 Message-Id: <20230307170031.018747379@linuxfoundation.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230307170001.594919529@linuxfoundation.org> References: <20230307170001.594919529@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Joseph Qi commit 54aa7f2330b82884f4a1afce0220add6e8312f8b upstream. Heming reported a BUG when using io_uring doing link-cp on ocfs2. [1] Do the following steps can reproduce this BUG: mount -t ocfs2 /dev/vdc /mnt/ocfs2 cp testfile /mnt/ocfs2/ ./link-cp /mnt/ocfs2/testfile /mnt/ocfs2/testfile.1 umount /mnt/ocfs2 Then umount will fail, and it outputs: umount: /mnt/ocfs2: target is busy. While tracing umount, it blames mnt_get_count() not return as expected. Do a deep investigation for fget()/fput() on related code flow, I've finally found that fget() leaks since ocfs2 doesn't support nowait buffered read. io_issue_sqe |-io_assign_file // do fget() first |-io_read |-io_iter_do_read |-ocfs2_file_read_iter // return -EOPNOTSUPP |-kiocb_done |-io_rw_done |-__io_complete_rw_common // set REQ_F_REISSUE |-io_resubmit_prep |-io_req_prep_async // override req->file, leak happens This was introduced by commit a196c78b5443 in v5.18. Fix it by don't re-assign req->file if it has already been assigned. [1] https://lore.kernel.org/ocfs2-devel/ab580a75-91c8-d68a-3455-40361be1bfa8@linux.alibaba.com/T/#t Fixes: a196c78b5443 ("io_uring: assign non-fixed early for async work") Cc: Reported-by: Heming Zhao Signed-off-by: Joseph Qi Cc: Xiaoguang Wang Link: https://lore.kernel.org/r/20230228045459.13524-1-joseph.qi@linux.alibaba.com Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- io_uring/io_uring.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -1597,7 +1597,7 @@ int io_req_prep_async(struct io_kiocb *r const struct io_op_def *def = &io_op_defs[req->opcode]; /* assign early for deferred execution for non-fixed file */ - if (def->needs_file && !(req->flags & REQ_F_FIXED_FILE)) + if (def->needs_file && !(req->flags & REQ_F_FIXED_FILE) && !req->file) req->file = io_file_get_normal(req, req->cqe.fd); if (!def->prep_async) return 0;