Hi
> Thanks for your effort, Kosaki.
> But I still doubt this patch is good.
>
> This patch makes early oom killing in hibernation as it skip
> all_unreclaimable check.
> Normally, hibernation needs many memory so page_reclaim pressure
> would be big in small memory system. So I don't like early give up.
Wait. When occur big pressure? hibernation reclaim pressure
(sc->nr_to_recliam) depend on physical memory size. therefore
a pressure seems to don't depend on the size.
> Do you think my patch has a problem? Personally, I think it's very
> simple and clear. :)
To be honest, I dislike following parts. It's madness on madness.
static bool zone_reclaimable(struct zone *zone)
{
if (zone->all_unreclaimable)
return false;
return zone->pages_scanned < zone_reclaimable_pages(zone) * 6;
}
The function require a reviewer know
o pages_scanned and all_unreclaimable are racy
o at hibernation, zone->all_unreclaimable can be false negative,
but can't be false positive.
And, a function comment of all_unreclaimable() says
/*
* As hibernation is going on, kswapd is freezed so that it can't mark
* the zone into all_unreclaimable. It can't handle OOM during hibernation.
* So let's check zone's unreclaimable in direct reclaim as well as kswapd.
*/
But, now it is no longer copy of kswapd algorithm.
If you strongly prefer this idea even if you hear above explanation,
please consider to add much and much comments. I can't say
current your patch is enough readable/reviewable.
Thanks.
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