Messages in this thread | | | Date | Sun, 19 Sep 2021 06:08:44 +0000 | From | Al Viro <> | Subject | Re: [PATCH -rc] init: don't panic if mount_nodev_root failed |
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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...
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