Re: [PATCH] mm: don't show nr_indirectly_reclaimable in /proc/vmstat

On Fri, Apr 27, 2018 at 11:17:01AM +0200, Vlastimil Babka wrote:

On 04/26/2018 11:55 PM, David Rientjes wrote:

quoted

On Thu, 26 Apr 2018, Michal Hocko wrote:

quoted

quoted

Don't show nr_indirectly_reclaimable in /proc/vmstat,
because there is no need in exporting this vm counter
to the userspace, and some changes are expected
in reclaimable object accounting, which can alter
this counter.

Signed-off-by: Roman Gushchin <redacted>
Cc: Vlastimil Babka <redacted>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>

This is quite a hack. I would much rather revert the counter and fixed
it the way Vlastimil has proposed. But if there is a strong opposition
to the revert then this is probably the simples thing to do. Therefore

Implementing this counter as a vmstat doesn't make much sense based on how 
it's used.  Do you have a link to what Vlastimil proposed?  I haven't seen 
mention of alternative ideas.

It was in the original thread, see e.g.
[ref]

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).

Thank you, Vlastimil!
That pretty much matches my understanding of the case.

BTW, are you planning to work on supporting reclaimable objects
by slab allocators?

Thanks!