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From: Oscar Salvador <osalvador@suse.de>
To: David Hildenbrand <david@redhat.com>
Cc: mhocko@kernel.org, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org, vbabka@suse.cz, pasha.tatashin@soleen.com
Subject: Re: [RFC PATCH v3 2/4] mm,memory_hotplug: Allocate memmap from the added memory range
Date: Wed, 9 Dec 2020 12:51:02 +0100	[thread overview]
Message-ID: <20201209115033.GA31745@linux> (raw)
In-Reply-To: <20201209103226.GC30892@linux>

On Wed, Dec 09, 2020 at 11:32:26AM +0100, Oscar Salvador wrote:
> On Wed, Dec 02, 2020 at 11:05:53AM +0100, David Hildenbrand wrote:
> > If you take a look at generic_online_page() there are some things that
> > won't be done for our vmemmap pages
> > 
> > 1. kernel_map_pages(page, 1 << order, 1);
> > 
> > We're accessing these pages already when initializing the memmap. We
> > might have to explicitly map these vmemmap pages at some point. Might
> > require some thought. Did you test with debug pagealloc?
> 
> I always try to run with all debug stuff enabled, but I definitely
> did not enable debug_pagealloc.
> I will have a look at it.
> 
> > 2. totalram_pages_add(1UL << order);
> > 
> > We should add/remove the vmemmap pages manually from totalram I guess.
> 
> Yes, we should. That was a clear oversight.

Looking closer, I do not think we have to account those into totalram.
I might be mistaken but looking at memblock_free_all, it seems we only
account to totalram_pages those ranges laying in memblock.memory filtering
out memblock.reserved.

And it seems that the pages we use for pglist_data structs (the ones we handle
in register_page_bootmem_info_node) fall in memblock.reserved.

-- 
Oscar Salvador
SUSE L3


  reply	other threads:[~2020-12-09 11:51 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-01 11:51 [RFC PATCH v3 0/4] Allocate memmap from hotadded memory (per device) Oscar Salvador
2020-12-01 11:51 ` [RFC PATCH v3 1/4] mm,memory_hotplug: Add mhp_supports_memmap_on_memory Oscar Salvador
2020-12-02  9:36   ` David Hildenbrand
2020-12-09  9:36     ` Oscar Salvador
2020-12-09  9:40       ` David Hildenbrand
2020-12-09  9:43         ` Oscar Salvador
2020-12-01 11:51 ` [RFC PATCH v3 2/4] mm,memory_hotplug: Allocate memmap from the added memory range Oscar Salvador
2020-12-02 10:05   ` David Hildenbrand
2020-12-09 10:32     ` Oscar Salvador
2020-12-09 11:51       ` Oscar Salvador [this message]
2020-12-01 11:51 ` [RFC PATCH v3 3/4] mm,memory_hotplug: Enable MHP_MEMMAP_ON_MEMORY when supported Oscar Salvador
2020-12-02  9:37   ` David Hildenbrand
2020-12-09  9:38     ` Oscar Salvador
2020-12-01 11:51 ` [RFC PATCH v3 4/4] mm,memory_hotplug: Add mhp_memmap_on_memory boot option Oscar Salvador
2020-12-02  9:42   ` David Hildenbrand
2020-12-09 10:02     ` Oscar Salvador
2020-12-09 10:04       ` David Hildenbrand

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