From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 84AB9C433EF for ; Tue, 14 Sep 2021 09:12:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 667A660295 for ; Tue, 14 Sep 2021 09:12:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231234AbhINJNq (ORCPT ); Tue, 14 Sep 2021 05:13:46 -0400 Received: from mail.kernel.org ([198.145.29.99]:50428 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230469AbhINJNe (ORCPT ); Tue, 14 Sep 2021 05:13:34 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 9918760295; Tue, 14 Sep 2021 09:12:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1631610736; bh=nRA/AHjgTMxHgowbKHAYAGp8F9pmWjOSvssEv7FfAPo=; h=From:To:Cc:Subject:Date:From; b=jNfqcdKLWHly1RIdwPJ+Gn64Z37hURjw6TrhdoaC0gcGuoZieq5cf+McCkBZsSLRD tBwQjyQMeQgfQZH4iI0alZDi3IUYHmIjRT1M6u36w5y/XpFXzXlmZTrZRt1Lf/hL37 MM5O/WYDgqcpXMsGe/GsoGwHVr75mxKOBbX9aaR8nHXYgFdGuIg1UHGUmjB0ytU83C lzUXv3ltkjAdoM0Y36ExFIg7GmKe+uAmlOUPSHfls7OT9obmUJXnWSCHrkyP58/Nry oKudAWbVDYRNnEgaZp+jrHSRq1uzQElwOFvaYSnA9XJ5peZohtas9moHUQx7evRvnd Z9d8BWxNMTbLA== From: Leon Romanovsky To: Al Viro , Christoph Hellwig Cc: Leon Romanovsky , linux-kernel@vger.kernel.org, Jason Gunthorpe Subject: [PATCH -rc] init: don't panic if mount_nodev_root failed Date: Tue, 14 Sep 2021 12:12:10 +0300 Message-Id: X-Mailer: git-send-email 2.31.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Leon Romanovsky Attempt to mount 9p file system as root gives the following kernel panic: 9pnet_virtio: no channels available for device root Kernel panic - not syncing: VFS: Unable to mount root "root" (9p), err=-2 CPU: 2 PID: 1 Comm: swapper/0 Not tainted 5.15.0-rc1+ #127 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014 Call Trace: dump_stack_lvl+0x45/0x59 panic+0x1e2/0x44b ? __warn_printk+0xf3/0xf3 ? free_unref_page+0x2d4/0x4a0 ? trace_hardirqs_on+0x32/0x120 ? free_unref_page+0x2d4/0x4a0 mount_root+0x189/0x1e0 prepare_namespace+0x136/0x165 kernel_init_freeable+0x3b8/0x3cb ? rest_init+0x2e0/0x2e0 kernel_init+0x19/0x130 ret_from_fork+0x1f/0x30 Kernel Offset: disabled ---[ end Kernel panic - not syncing: VFS: Unable to mount root "root" (9p), err=-2 ]--- QEMU command line: "qemu-system-x86_64 -append root=/dev/root rw rootfstype=9p rootflags=trans=virtio ..." This error is because root_device_name is truncated in prepare_namespace() from being "/dev/root" to be "root" prior to call to mount_nodev_root(). As a solution, don't treat errors in mount_nodev_root() as errors that require panics and allow failback to the mount flow that existed before patch citied in Fixes tag. Fixes: f9259be6a9e7 ("init: allow mounting arbitrary non-blockdevice filesystems as root") Signed-off-by: Leon Romanovsky --- I'm not sure if this is the right thing to do, but it works for me. --- init/do_mounts.c | 3 --- 1 file changed, 3 deletions(-) diff --git a/init/do_mounts.c b/init/do_mounts.c index 2ed30ff6c906..b423ea7dcc6b 100644 --- a/init/do_mounts.c +++ b/init/do_mounts.c @@ -553,9 +553,6 @@ static int __init mount_nodev_root(void) root_mount_data); if (!err) break; - if (err != -EACCES && err != -EINVAL) - panic("VFS: Unable to mount root \"%s\" (%s), err=%d\n", - root_device_name, fstype, err); } free_page((unsigned long)fs_names); -- 2.31.1