linux-kernel - Re: [PATCH 03/10] mm/migrate: update node demotion order during on hotplug events

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20210409101400.GA32159@linux>
Date:   Fri, 9 Apr 2021 12:14:04 +0200
From:   Oscar Salvador <osalvador@...e.de>
To:     Dave Hansen <dave.hansen@...ux.intel.com>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        shy828301@...il.com, weixugc@...gle.com, rientjes@...gle.com,
        ying.huang@...el.com, dan.j.williams@...el.com, david@...hat.com
Subject: Re: [PATCH 03/10] mm/migrate: update node demotion order during on
 hotplug events

On Thu, Apr 08, 2021 at 11:52:51AM +0200, Oscar Salvador wrote:
> I am not really into PMEM, and I ignore whether we need
> CONFIG_MEMORY_HOTPLUG in order to have such memory on the system.
> If so, the following can be partly ignored.

Ok, I refreshed by memory with [1].
>From that, it seems that in order to use PMEM as RAM we need CONFIG_MEMORY_HOTPLUG.
But is that always the case? Can happen that in some scenario PMEM comes ready
to use and we do not need the hotplug trick?

Anyway, I would still like to clarify the state of the HOTPLUG_CPU.
On x86_64, HOTPLUG_CPU and MEMORY_HOTPLUG are tied by SPM means, but on arm64
one can have MEMORY_HOTPLUG while not having picked HOTPLUG_CPU.

My point is that we might want to put the callback functions and the callback
registration for cpu-hotplug guarded by its own HOTPLUG_CPU instead of guarding it
in the same MEMORY_HOTPLUG block to make it more clear?

-- 
Oscar Salvador
SUSE L3