linux-kernel - Re: [PATCH 3/6] struct page: add field for vm

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Date:   Wed, 31 Jan 2018 18:00:36 -0600 (CST)
From:   Christopher Lameter <cl@...ux.com>
To:     Igor Stoppa <igor.stoppa@...wei.com>
cc:     jglisse@...hat.com, keescook@...omium.org, mhocko@...nel.org,
        labbott@...hat.com, hch@...radead.org, willy@...radead.org,
        linux-security-module@...r.kernel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, kernel-hardening@...ts.openwall.com
Subject: Re: [PATCH 3/6] struct page: add field for vm_struct

On Tue, 30 Jan 2018, Igor Stoppa wrote:

> @@ -1769,6 +1774,9 @@ void *__vmalloc_node_range(unsigned long size, unsigned long align,
>
>  	kmemleak_vmalloc(area, size, gfp_mask);
>
> +	for (page_counter = 0; page_counter < area->nr_pages; page_counter++)
> +		area->pages[page_counter]->area = area;
> +
>  	return addr;

Well this introduces significant overhead for large sized allocation. Does
this not matter because the areas are small?

Would it not be better to use compound page allocations here?
page_head(whatever) gets you the head page where you can store all sorts
of information about the chunk of memory.