From: Al Viro <viro@zeniv.linux.org.uk>
To: Leon Romanovsky <leonro@nvidia.com>
Cc: Christoph Hellwig <hch@lst.de>,
linux-kernel@vger.kernel.org, Jason Gunthorpe <jgg@nvidia.com>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH -rc] init: don't panic if mount_nodev_root failed
Date: Sun, 19 Sep 2021 06:08:44 +0000 [thread overview]
Message-ID: <YUbT7H4fD0KvnbLa@zeniv-ca.linux.org.uk> (raw)
In-Reply-To: <YUbOv01OaWh9fQHp@unreal>
On Sun, Sep 19, 2021 at 08:46:39AM +0300, Leon Romanovsky wrote:
> On Tue, Sep 14, 2021 at 12:12:10PM +0300, Leon Romanovsky wrote:
> > From: Leon Romanovsky <leonro@nvidia.com>
> >
> > 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 <leonro@nvidia.com>
> > ---
> > 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(-)
>
> Hi,
>
> I assume that after Christoph gave his ROB [1], the patch is ok.
> Should I do anything else in order to progress with merging it?
Sits in the local pile; will go to Linus tomorrow...
next prev parent reply other threads:[~2021-09-19 6:41 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-14 9:12 [PATCH -rc] init: don't panic if mount_nodev_root failed Leon Romanovsky
2021-09-14 15:07 ` Christoph Hellwig
2021-09-19 5:46 ` Leon Romanovsky
2021-09-19 6:08 ` Al Viro [this message]
2021-09-19 6:38 ` Leon Romanovsky
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=YUbT7H4fD0KvnbLa@zeniv-ca.linux.org.uk \
--to=viro@zeniv.linux.org.uk \
--cc=hch@lst.de \
--cc=jgg@nvidia.com \
--cc=leonro@nvidia.com \
--cc=linux-kernel@vger.kernel.org \
--cc=torvalds@linux-foundation.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.