From: Mike Rapoport <rppt@kernel.org>
To: David Hildenbrand <david@redhat.com>
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 13:22:07 +0300 [thread overview]
Message-ID: <YO1pT1bjMfldbQKg@kernel.org> (raw)
In-Reply-To: <7300dfe1-0c6a-ae2e-2c48-c885248ec263@redhat.com>
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.
> For now, this looks like the right thing to do
>
> Acked-by: David Hildenbrand <david@redhat.com>
Thanks!
--
Sincerely yours,
Mike.
next prev parent reply other threads:[~2021-07-13 10:22 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-13 8:00 [PATCH 0/2] mm: remove pfn_valid_within() and CONFIG_HOLES_IN_ZONE 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 [this message]
2021-07-13 10:24 ` David Hildenbrand
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
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