linux-kernel - Re: [PATCH 2/5] mm,memory_hotplug: Allocate memmap from the added memory range

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Message-ID: <20210125133544.GA31473@linux>
Date:   Mon, 25 Jan 2021 14:36:20 +0100
From:   Oscar Salvador <osalvador@...e.de>
To:     David Hildenbrand <david@...hat.com>
Cc:     akpm@...ux-foundation.org, mhocko@...nel.org,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org, vbabka@...e.cz,
        pasha.tatashin@...een.com
Subject: Re: [PATCH 2/5] mm,memory_hotplug: Allocate memmap from the added
 memory range

On Mon, Jan 25, 2021 at 12:02:53PM +0100, David Hildenbrand wrote:
> Assume you have two consecutive memory blocks with 56 sizeof(struct page).
> The first one allocates a PMD (2097152) but only consumes 1835008, the second
> one reuses the remaining part and allocates another PMD (1835008),
> only using parts of it.
> 
> Ripping out a memory block, along with the PMD in the vmemmap would
> remove parts of the vmemmap of another memory block.

Bleh, yeah, I was confused, you are right.

> You might want to take a look at:

Thanks a lot for the hints, I will have a look ;-)


-- 
Oscar Salvador
SUSE L3