From: David Hildenbrand <david@redhat.com>
To: Mike Rapoport <rppt@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Mike Rapoport <rppt@linux.ibm.com>,
"Rafael J. Wysocki" <rafael@kernel.org>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH 1/2] mm: remove pfn_valid_within() and CONFIG_HOLES_IN_ZONE
Date: Tue, 13 Jul 2021 12:24:41 +0200 [thread overview]
Message-ID: <4367d5e4-4f03-6d99-f19b-9d32b71f227d@redhat.com> (raw)
In-Reply-To: <YO1pT1bjMfldbQKg@kernel.org>
On 13.07.21 12:22, Mike Rapoport wrote:
> On Tue, Jul 13, 2021 at 11:51:46AM +0200, David Hildenbrand wrote:
>> On 13.07.21 10:00, Mike Rapoport wrote:
>>> From: Mike Rapoport <rppt@linux.ibm.com>
>>>
>>> After recent changes in freeing of the unused parts of the memory map and
>>> rework of pfn_valid() in arm and arm64 there are no architectures that can
>>> have holes in the memory map within a pageblock and so nothing can enable
>>> CONFIG_HOLES_IN_ZONE which guards non trivial implementation of
>>> pfn_valid_within().
>>>
>>> With that, pfn_valid_within() is always hardwired to 1 and can be
>>> completely removed.
>>>
>>> Remove calls to pfn_valid_within() and CONFIG_HOLES_IN_ZONE.
>>>
>>> Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
>>
>> There is currently the discussion to increase MAX_ORDER, for example, to
>> cover 1GiB instead of 4MiB on x86-64. This would mean that we could
>> suddenly, again, have holes insides MAX_ORDER - 1 pages.
>>
>> So I assume if we ever go down that path, we'll need something like this
>> again.
>
> It depends whether pageblock_order will be also increased. PFN walkers rely
> on continuity of pageblocks rather than MAX_ORDER chunks, so if
> pageblock_order won't change, there won't be need to check for pfn_valid()
> inside a pageblock.
I'm pushing for letting pageblocks stay untouched, so good to know!
(we still have this crazy special case of pageblocks > MAX_ORDER - 1
right now, which I think we should just eliminate)
--
Thanks,
David / dhildenb
next prev parent reply other threads:[~2021-07-13 10:24 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-13 8:00 [PATCH 0/2] " Mike Rapoport
2021-07-13 8:00 ` [PATCH 1/2] " Mike Rapoport
2021-07-13 9:51 ` David Hildenbrand
2021-07-13 10:22 ` Mike Rapoport
2021-07-13 10:24 ` David Hildenbrand [this message]
2021-07-13 20:02 ` Zi Yan
2021-07-13 8:00 ` [PATCH 2/2] mm: memory_hotplug: cleanup after removal of pfn_valid_within() Mike Rapoport
2021-07-13 9:54 ` David Hildenbrand
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=4367d5e4-4f03-6d99-f19b-9d32b71f227d@redhat.com \
--to=david@redhat.com \
--cc=akpm@linux-foundation.org \
--cc=gregkh@linuxfoundation.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=rafael@kernel.org \
--cc=rppt@kernel.org \
--cc=rppt@linux.ibm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox