Description: Kernel versions 4.17.4-4.17.6 contain bug which lockups the system:
This bug is fixed in kernel 4.17.7 with commit 5ea45736209c8efd04ed793f81084925097f84ed. Please backport it.

commit 5ea45736209c8efd04ed793f81084925097f84ed
Author: Pavel Tatashin <pasha.tatashin@oracle.com>
Date: Sat Jul 14 09:15:07 2018 -0400

mm: zero unavailable pages before memmap init

commit e181ae0c5db9544de9c53239eb22bc012ce75033 upstream.

We must zero struct pages for memory that is not backed by physical
memory, or kernel does not have access to.

Recently, there was a change which zeroed all memmap for all holes in
e820. Unfortunately, it introduced a bug that is discussed here:

https://www.spinics.net/lists/linux-mm/msg156764.html

Linus, also saw this bug on his machine, and confirmed that reverting
commit 124049decbb1 ("x86/e820: put !E820_TYPE_RAM regions into
memblock.reserved") fixes the issue.

The problem is that we incorrectly zero some struct pages after they
were setup.

The fix is to zero unavailable struct pages prior to initializing of
struct pages.

A more detailed fix should come later that would avoid double zeroing
cases: one in __init_single_page(), the other one in
zero_resv_unavail().

Fixes: 124049decbb1 ("x86/e820: put !E820_TYPE_RAM regions into memblock.reserved")

Note that kernel 4.17.7 itself does not boot on 32-bit systems:
https://lkml.org/lkml/2018/7/17/434