From: David Hildenbrand <david@redhat.com>
To: Oscar Salvador <osalvador@suse.de>,
Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@kernel.org>,
Anshuman Khandual <anshuman.khandual@arm.com>,
Vlastimil Babka <vbabka@suse.cz>,
Pavel Tatashin <pasha.tatashin@soleen.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5 1/5] mm,memory_hotplug: Allocate memmap from the added memory range
Date: Fri, 19 Mar 2021 11:20:19 +0100 [thread overview]
Message-ID: <c41ea8ac-e99d-6d23-c7b9-5ca25ffb72bb@redhat.com> (raw)
In-Reply-To: <20210319092635.6214-2-osalvador@suse.de>
Tow NITs
> +bool mhp_supports_memmap_on_memory(unsigned long size)
> +{
> + unsigned long nr_vmemmap_pages = size / PAGE_SIZE;
> + unsigned long vmemmap_size = nr_vmemmap_pages * sizeof(struct page);
> + unsigned long remaining_size = size - vmemmap_size;
> +
> + /*
> + * Besides having arch support and the feature enabled at runtime, we
> + * need a few more assumptions to hold true:
> + *
> + * a) We span a single memory block: memory onlining/offlinin;g happens
s/offlinin;g/offlining;/
> + * in memory block granularity. We don't want the vmemmap of online
> + * memory blocks to reside on offline memory blocks. In the future,
> + * we might want to support variable-sized memory blocks to make the
> + * feature more versatile.
> + *
> + * b) The vmemmap pages span complete PMDs: We don't want vmemmap code
> + * to populate memory from the altmap for unrelated parts (i.e.,
> + * other memory blocks)
> + *
> + * c) The vmemmap pages (and thereby the pages that will be exposed to
> + * the buddy) have to cover full pageblocks: memory onlining/offlining
> + * code requires applicable ranges to be page-aligned, for example, to
> + * set the migratetypes properly.
> + *
> + * TODO: Although we have a check here to make sure that vmemmap pages
> + * fully populate a PMD, it is not the right place to check for
> + * this. A much better solution involves improving vmemmap code
> + * to fallback to base pages when trying to populate vmemmap using
> + * altmap as an alternative source of memory, and we do not exactly
> + * populate a single PMD.
> + */
> + return memmap_on_memory &&
> + IS_ENABLED(CONFIG_MHP_MEMMAP_ON_MEMORY) &&
> + size == memory_block_size_bytes() &&
> + IS_ALIGNED(vmemmap_size, PMD_SIZE) &&
> + IS_ALIGNED(remaining_size, (pageblock_nr_pages << PAGE_SHIFT));
IS_ALIGNED(remaining_size, pageblock_nr_pages << PAGE_SHIFT);
LGTM, thanks!
(another pair of eyes certainly wouldn't hurt :) )
Reviewed-by: David Hildenbrand <david@redhat.com>
--
Thanks,
David / dhildenb
next prev parent reply other threads:[~2021-03-19 10:21 UTC|newest]
Thread overview: 63+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-19 9:26 [PATCH v5 0/5] Allocate memmap from hotadded memory (per device) Oscar Salvador
2021-03-19 9:26 ` [PATCH v5 1/5] mm,memory_hotplug: Allocate memmap from the added memory range Oscar Salvador
2021-03-19 10:20 ` David Hildenbrand [this message]
2021-03-19 10:31 ` Oscar Salvador
2021-03-19 12:04 ` David Hildenbrand
2021-03-23 10:11 ` Michal Hocko
2021-03-24 10:12 ` Oscar Salvador
2021-03-24 12:03 ` Michal Hocko
2021-03-24 12:10 ` Michal Hocko
2021-03-24 12:23 ` David Hildenbrand
2021-03-24 12:37 ` Michal Hocko
2021-03-24 13:13 ` David Hildenbrand
2021-03-24 13:40 ` Michal Hocko
2021-03-24 14:05 ` David Hildenbrand
2021-03-24 13:27 ` Oscar Salvador
2021-03-24 14:42 ` Michal Hocko
2021-03-24 14:52 ` David Hildenbrand
2021-03-24 16:04 ` Michal Hocko
2021-03-24 19:16 ` David Hildenbrand
2021-03-25 8:07 ` Oscar Salvador
2021-03-25 9:17 ` Michal Hocko
2021-03-25 10:55 ` Oscar Salvador
2021-03-25 11:08 ` David Hildenbrand
2021-03-25 11:23 ` Oscar Salvador
2021-03-25 12:35 ` Michal Hocko
2021-03-25 12:40 ` David Hildenbrand
2021-03-25 14:08 ` Michal Hocko
2021-03-25 14:09 ` David Hildenbrand
2021-03-25 14:34 ` Michal Hocko
2021-03-25 14:46 ` David Hildenbrand
2021-03-25 15:12 ` Michal Hocko
2021-03-25 15:19 ` David Hildenbrand
2021-03-25 15:35 ` Michal Hocko
2021-03-25 15:40 ` David Hildenbrand
2021-03-25 16:07 ` Michal Hocko
2021-03-25 16:20 ` David Hildenbrand
2021-03-25 16:36 ` Michal Hocko
2021-03-25 16:47 ` Michal Hocko
2021-03-25 16:55 ` David Hildenbrand
2021-03-25 22:06 ` Oscar Salvador
2021-03-26 8:35 ` Michal Hocko
2021-03-26 8:52 ` David Hildenbrand
2021-03-26 8:57 ` Oscar Salvador
2021-03-26 12:15 ` Oscar Salvador
2021-03-26 13:36 ` David Hildenbrand
2021-03-26 14:38 ` Michal Hocko
2021-03-26 14:53 ` David Hildenbrand
2021-03-26 15:31 ` Michal Hocko
2021-03-26 16:03 ` David Hildenbrand
2021-03-26 8:55 ` Oscar Salvador
2021-03-26 9:11 ` Michal Hocko
2021-03-25 18:08 ` David Hildenbrand
2021-03-25 12:26 ` Michal Hocko
2021-03-25 14:02 ` Oscar Salvador
2021-03-25 14:40 ` Michal Hocko
2021-03-19 9:26 ` [PATCH v5 2/5] acpi,memhotplug: Enable MHP_MEMMAP_ON_MEMORY when supported Oscar Salvador
2021-03-23 10:40 ` Michal Hocko
2021-03-19 9:26 ` [PATCH v5 3/5] mm,memory_hotplug: Add kernel boot option to enable memmap_on_memory Oscar Salvador
2021-03-23 10:47 ` Michal Hocko
2021-03-24 8:45 ` Oscar Salvador
2021-03-24 9:02 ` Michal Hocko
2021-03-19 9:26 ` [PATCH v5 4/5] x86/Kconfig: Introduce ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE Oscar Salvador
2021-03-19 9:26 ` [PATCH v5 5/5] arm64/Kconfig: " Oscar Salvador
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