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Date: Fri, 14 Dec 2018 10:29:04 -0800
From: Matthew Wilcox <willy@infradead.org>
Subject: Re: [RFC 4/4] mm: show number of vmalloc pages in /proc/meminfo
Message-ID: <20181214182904.GE10600@bombadil.infradead.org>
References: <20181214180720.32040-1-guro@fb.com>
 <20181214180720.32040-5-guro@fb.com>
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Sender: owner-linux-mm@kvack.org
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To: Roman Gushchin <guroan@gmail.com>
Cc: linux-mm@kvack.org, Alexey Dobriyan <adobriyan@gmail.com>, Johannes Weiner <hannes@cmpxchg.org>, Michal Hocko <mhocko@suse.com>, Vlastimil Babka <vbabka@suse.cz>, linux-kernel@vger.kernel.org, kernel-team@fb.com, Roman Gushchin <guro@fb.com>

On Fri, Dec 14, 2018 at 10:07:20AM -0800, Roman Gushchin wrote:
> Vmalloc() is getting more and more used these days (kernel stacks,
> bpf and percpu allocator are new top users), and the total %
> of memory consumed by vmalloc() can be pretty significant
> and changes dynamically.
> 
> /proc/meminfo is the best place to display this information:
> its top goal is to show top consumers of the memory.
> 
> Since the VmallocUsed field in /proc/meminfo is not in use
> for quite a long time (it has been defined to 0 by the
> commit a5ad88ce8c7f ("mm: get rid of 'vmalloc_info' from
> /proc/meminfo")), let's reuse it for showing the actual
> physical memory consumption of vmalloc().

Do you see significant contention on nr_vmalloc_pages?  Also, if it's
just an atomic_long_t, is it worth having an accessor for it?  And if
it is worth having an accessor for it, then it can be static.

Also, I seem to be missing 3/4.