Re: [PATCH v2 00/28] The new cgroup slab memory controller

[David Hildenbrand]

> Am 02.09.2020 um 11:53 schrieb Vlastimil Babka <vbabka@xxxxxxx>:
> 
> On 8/28/20 6:47 PM, Pavel Tatashin wrote:
>> There appears to be another problem that is related to the
>> cgroup_mutex -> mem_hotplug_lock deadlock described above.
>> 
>> In the original deadlock that I described, the workaround is to
>> replace crash dump from piping to Linux traditional save to files
>> method. However, after trying this workaround, I still observed
>> hardware watchdog resets during machine  shutdown.
>> 
>> The new problem occurs for the following reason: upon shutdown systemd
>> calls a service that hot-removes memory, and if hot-removing fails for
> 
> Why is that hotremove even needed if we're shutting down? Are there any
> (virtualization?) platforms where it makes some difference over plain
> shutdown/restart?

If all it‘s doing is offlining random memory that sounds unnecessary and dangerous. Any pointers to this service so we can figure out what it‘s doing and why? (Arch? Hypervisor?)