linux-kernel - Re: [PATCH v1] drivers/base/memory.c: Don't store end_section

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Message-ID: <21d48bda-dfc8-1c7e-6b3a-81a33c8ea4ac@redhat.com>
Date:   Wed, 31 Jul 2019 16:23:45 +0200
From:   David Hildenbrand <david@...hat.com>
To:     Michal Hocko <mhocko@...nel.org>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Pavel Tatashin <pasha.tatashin@...een.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Oscar Salvador <osalvador@...e.de>
Subject: Re: [PATCH v1] drivers/base/memory.c: Don't store end_section_nr in
 memory blocks

On 31.07.19 16:15, Michal Hocko wrote:
> On Wed 31-07-19 16:04:10, David Hildenbrand wrote:
>> On 31.07.19 15:42, David Hildenbrand wrote:
> [...]
>>> Powerpc userspace queries it:
>>> https://groups.google.com/forum/#!msg/powerpc-utils-devel/dKjZCqpTxus/AwkstV2ABwAJ
>>
>> FWIW, powerpc-utils also uses the "removable" property - which means
>> we're also stuck with that unfortunately. :(
> 
> Yeah, I am aware of that and I strongly suspect this is actually in use
> because it is terribly unreliable for any non-idle system. There is
> simply no way to find out whether something is offlinable than to try
> it.

According to the introducing commit "removable" is only used to not even
try some memory blocks (IOW to save cpu cycles) - not treated as a
guaranteed (which is correct).

-- 

Thanks,

David / dhildenb