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Leon Romanovsky 40c8ee67cf init: don't panic if mount_nodev_root failed 
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: f9259be6a9 ("init: allow mounting arbitrary non-blockdevice filesystems as root")
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2021-09-19 22:24:52 -04:00
arch A set of x86 fixes: 2021-09-19 13:29:36 -07:00
block blk-cgroup: fix UAF by grabbing blkcg lock before destroying blkg pd 2021-09-15 12:03:18 -06:00
certs certs: Add support for using elliptic curve keys for signing modules 2021-08-23 19:55:42 +03:00
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2021-08-30 12:57:10 -07:00
Documentation Devicetree fixes for v5.15, take 2: 2021-09-18 12:40:55 -07:00
drivers dmascc: use proper 'virt_to_bus()' rather than casting to 'int' 2021-09-19 10:49:42 -07:00
fs iov_iter.3-5.15-2021-09-17 2021-09-17 09:23:44 -07:00
include pci_iounmap'2: Electric Boogaloo: try to make sense of it all 2021-09-19 17:13:35 -07:00
init init: don't panic if mount_nodev_root failed 2021-09-19 22:24:52 -04:00
ipc ipc: remove memcg accounting for sops objects in do_semtimedop() 2021-09-14 10:22:11 -07:00
kernel A single fix for the perf core where a value read with READ_ONCE() was 2021-09-19 13:22:40 -07:00
lib pci_iounmap'2: Electric Boogaloo: try to make sense of it all 2021-09-19 17:13:35 -07:00
LICENSES LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes" 2021-07-15 06:31:24 -06:00
mm memblock: introduce saner 'memblock_free_ptr()' interface 2021-09-14 13:23:22 -07:00
net Networking fixes for 5.15-rc2, including fixes from bpf. 2021-09-16 13:05:42 -07:00
samples kgdb patches for 5.15 2021-09-07 12:08:04 -07:00
scripts Kbuild fixes for v5.15 2021-09-19 12:55:12 -07:00
security Kbuild updates for v5.15 2021-09-03 15:33:47 -07:00
sound sound fixes for 5.15-rc1 2021-09-09 16:05:10 -07:00
tools powerpc fixes for 5.15 #2 2021-09-19 13:00:23 -07:00
usr .gitignore: prefix local generated files with a slash 2021-05-02 00:43:35 +09:00
virt KVM: Drop unused kvm_dirty_gfn_invalid() 2021-09-06 08:23:46 -04:00
.clang-format clang-format: Update with the latest for_each macro list 2021-05-12 23:32:39 +02:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap mailmap: update email address of Matthias Fuchs and Thomas Körper 2021-08-19 09:39:44 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: move Murali Karicheri to credits 2021-04-29 15:47:30 -07:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS MAINTAINERS: Add Nirmal Patel as VMD maintainer 2021-09-15 16:44:03 -05:00
Makefile Linux 5.15-rc2 2021-09-19 17:28:22 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.