Subject: linux-next: panic on boot

From: Stephen Rothwell <[email-masked]>
Date: Mon, 3 Aug 2020 21:44:33 +1000

Hi all,

As part of my testing of linux-next, I do a qemu boot of a powerpc
pseries_le_defconfig build.  Today it paniced after reaching user mode
(but before the console login prompt):

[    2.286787][    T1] Run /init as init process
[    2.557885][   T50] mount (50) used greatest stack depth: 10880 bytes left
[    2.574629][    T1] Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000200
[    2.575079][    T1] CPU: 0 PID: 1 Comm: init Not tainted 5.8.0 #2
[    2.575421][    T1] Call Trace:
[    2.576197][    T1] [c00000007e3a3b90] [c0000000006f5de0] dump_stack+0xc4/0x114 (unreliable)
[    2.576450][    T1] [c00000007e3a3be0] [c000000000122318] panic+0x16c/0x404
[    2.576540][    T1] [c00000007e3a3c80] [c00000000012a690] do_exit+0xc70/0xd10
[    2.576613][    T1] [c00000007e3a3d60] [c00000000012a804] do_group_exit+0x64/0x110
[    2.576812][    T1] [c00000007e3a3da0] [c00000000012a8d4] sys_exit_group+0x24/0x30
[    2.576891][    T1] [c00000007e3a3dc0] [c000000000032cbc] system_call_exception+0x14c/0x230
[    2.576969][    T1] [c00000007e3a3e20] [c00000000000d740] system_call_common+0xf0/0x27c

This boot is of a simple initramfs whose only purpose is to shutdown.

/init is a shell script:

#!/bin/sh
# devtmpfs does not get automounted for initramfs
/bin/mount -t devtmpfs devtmpfs /dev
exec 0</dev/console
exec 1>/dev/console
exec 2>/dev/console
exec /sbin/init $*

/sbin/init is busybox and this is the /etc/inittab

::sysinit:/bin/mount -t proc proc /proc
::sysinit:/bin/mount -o remount,rw /
::sysinit:/bin/mkdir -p /dev/pts
::sysinit:/bin/mkdir -p /dev/shm
::sysinit:/bin/mount -a
::sysinit:/bin/hostname -F /etc/hostname
::sysinit:/etc/init.d/rcS
console::respawn:/sbin/getty -L  console 0 vt100 # GENERIC_SERIAL
::shutdown:/etc/init.d/rcK
::shutdown:/sbin/swapoff -a
::shutdown:/bin/umount -a -r

and there are no init scripts.

Chritoph and Al are cc'd since we have some init stuff rewrite in the
vfs tree for the first time today.
-- 
Cheers,
Stephen Rothwell