linux-kernel - Re: [PATCH] mm: don't show nr_indirectly

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Date:   Fri, 27 Apr 2018 11:57:08 -0700
From:   Matthew Wilcox <willy@...radead.org>
To:     David Rientjes <rientjes@...gle.com>
Cc:     Vlastimil Babka <vbabka@...e.cz>, Michal Hocko <mhocko@...nel.org>,
        Roman Gushchin <guro@...com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, linux-api@...r.kernel.org,
        kernel-team@...com, Andrew Morton <akpm@...ux-foundation.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Johannes Weiner <hannes@...xchg.org>
Subject: Re: [PATCH] mm: don't show nr_indirectly_reclaimable in /proc/vmstat

On Fri, Apr 27, 2018 at 11:41:31AM -0700, David Rientjes wrote:
> On Fri, 27 Apr 2018, Vlastimil Babka wrote:
> 
> > It was in the original thread, see e.g.
> > <08524819-14ef-81d0-fa90-d7af13c6b9d5@...e.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()?

I'd think you'd want one atomic_t per NUMA node at least ...