The patch titled
Subject: init/mount: print pretty name of root device when panicing
has been added to the -mm mm-nonmm-unstable branch. Its filename is
init-mount-print-pretty-name-of-root-device-when-panics.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/init-mount-print-pretty-name-of-root-device-when-panics.patch
This patch will later appear in the mm-nonmm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Jianyong Wu <jianyong.wu@xxxxxxx>
Subject: init/mount: print pretty name of root device when panicing
Date: Thu, 7 Sep 2023 09:10:25 +0000
Given a wrong root device, current log may not give the pretty name
which is useful to locate root cause.
For example, there are 2 blk devs in a VM, /dev/vda which has 2 partitials
/dev/vda1 and /dev/vda2 and /dev/vdb which is blank. /dev/vda2 is the
right root dev. When set "root=/dev/vdb", we get error log:
[ 0.635575] Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(254,16)
It's not straightforward to find out the root cause as there is lack of
the root devive name therefore hard for people to get those info from the
device number, in the example, (254,16).
It is more comprehensive way to hint the root cause if pretty name is
given here, like:
[ 0.559887] Kernel panic - not syncing: VFS: Unable to mount root fs on "/dev/vdb" or unknown-block(254,16)
Link: https://lkml.kernel.org/r/20230907091025.3436878-1-jianyong.wu@xxxxxxx
Signed-off-by: Jianyong Wu <jianyong.wu@xxxxxxx>
Cc: Christian Brauner <brauner@xxxxxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Cc: Justin He <justin.he@xxxxxxx>
Cc: Loic Poulain <loic.poulain@xxxxxxxxxx>
Cc: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
init/do_mounts.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/init/do_mounts.c~init-mount-print-pretty-name-of-root-device-when-panics
+++ a/init/do_mounts.c
@@ -244,7 +244,7 @@ retry:
for (i = 0, p = fs_names; i < num_fs; i++, p += strlen(p)+1)
printk(" %s", p);
printk("\n");
- panic("VFS: Unable to mount root fs on %s", b);
+ panic("VFS: Unable to mount root fs on \"%s\" or %s", pretty_name, b);
out:
put_page(page);
}
_
Patches currently in -mm which might be from jianyong.wu@xxxxxxx are
init-mount-print-pretty-name-of-root-device-when-panics.patch
