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Date:   Fri, 27 Apr 2018 11:41:31 -0700 (PDT)
From:   David Rientjes <rientjes@google.com>
To:     Vlastimil Babka <vbabka@suse.cz>
cc:     Michal Hocko <mhocko@kernel.org>, Roman Gushchin <guro@fb.com>,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        linux-api@vger.kernel.org, kernel-team@fb.com,
        Matthew Wilcox <willy@infradead.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Johannes Weiner <hannes@cmpxchg.org>
Subject: Re: [PATCH] mm: don't show nr_indirectly_reclaimable in
 /proc/vmstat
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On Fri, 27 Apr 2018, Vlastimil Babka wrote:

> It was in the original thread, see e.g.
> <08524819-14ef-81d0-fa90-d7af13c6b9d5@suse.cz>
> 
> However it will take some time to get that in mainline, and meanwhile
> the current implementation does prevent a DOS. So I doubt it can be
> fully reverted - as a compromise I just didn't want the counter to
> become ABI. TBH though, other people at LSF/MM didn't seem concerned
> that /proc/vmstat is an ABI that we can't change (i.e. counters have
> been presumably removed in the past already).
> 

What prevents this from being a simple atomic_t that gets added to in 
__d_alloc(), subtracted from in __d_free_external_name(), and read in 
si_mem_available() and __vm_enough_memory()?