Re: [PATCH] mm, vmscan: do not loop on too_many_isolated for ever

[Rik van Riel]

On Thu, 2017-03-09 at 10:12 +0100, Michal Hocko wrote:
> On Wed 08-03-17 10:54:57, Rik van Riel wrote:

> > In fact, false OOM kills with that kind of workload is
> > how we ended up getting the "too many isolated" logic
> > in the first place.
> Right, but the retry logic was considerably different than what we
> have these days. should_reclaim_retry considers amount of reclaimable
> memory. As I've said earlier if we see a report where the oom hits
> prematurely with many NR_ISOLATED* we know how to fix that.

Would it be enough to simply reset no_progress_loops
in this check inside should_reclaim_retry, if we know
pageout IO is pending?

            if (!did_some_progress) {
ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂunsigned long write_pending;

ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂwrite_pending =
zone_page_state_snapshot(zone,
ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂNR_ZONE_WRITE_P
ENDING);

ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂif (2 * write_pending > reclaimable) {
ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂcongestion_wait(BLK_RW_ASYNC,
HZ/10);
ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂreturn true;
ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ}
ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ}

-- 
All rights reversed

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