A panic when reboot --force the system

Hi，list

I encounter a panic about init process.

Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000007

Pid: 1, comm: init Tainted: G R O 3.4.24.19-0.11-default #1

Call Trace:
 [<ffffffff8144dd24>] panic+0xc1/0x1e2
 [<ffffffff8104483b>] do_exit+0x7db/0x8d0
 [<ffffffff81044c7a>] do_group_exit+0x3a/0xa0
 [<ffffffff8105394b>] get_signal_to_deliver+0x1ab/0x5e0
 [<ffffffff81002270>] do_signal+0x60/0x5f0
 [<ffffffff8145bf97>] ? do_page_fault+0x4a7/0x4d0
 [<ffffffff81170d2c>] ? poll_select_copy_remaining+0xec/0x140
 [<ffffffff81002885>] do_notify_resume+0x65/0x80
 [<ffffffff8124ca7e>] ? trace_hardirqs_on_thunk+0x3a/0x3c
 [<ffffffff814587ab>] retint_signal+0x4d/0x92

The system has a little memory left, then reboot it, and get the panic.

In our host, kswapd would be wake up while using a lot of memory, and then reclaim some pages from init process. If we execute *"reboot"* or *"reboot -f"* to reboot host through sysvinit, reboot process will call sys_reboot and shut down the sas driver(disk), then will trigger the panic of init process.

As follow,

HOST reboot process init process
use a lot of memory
wake up kswapd
reclaim some pages
(these pages are code segment
or data segment of init process)
from init thread (pid=1)
reboot
sys_reboot
shutdown disk driver
init thread read data from disk
page_fault
filemap_fault
readpage failed because the disk is closed
return VM_FAULT_SIGBUS send signal SIGBUS
do_signal
do_exit
trigger the panic

It seems that reboot or force reboot through *sysvinit* have the problem. Furthermore, using reboot -f in *systemd* should also have this problem, right?

And is that a bug for current reboot process in sysvinit or systemd?

All comments are welcome, thanks.

init thread read data from disk

Hi,

Does anyone know will init thread read data from disk after shutdown the disk driver?

Thanks,
Xishi Qiu

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