Hi Mel, On Wed, Jul 20, 2016 at 04:21:46PM +0100, Mel Gorman wrote: > Both Joonsoo Kim and Minchan Kim have reported premature OOM kills on > a 32-bit platform. The common element is a zone-constrained high-order > allocation failing. Two factors appear to be at fault -- pgdat being
Strictly speaking, my case is order-0 allocation failing, not high-order. ;) > considered unreclaimable prematurely and insufficient rotation of the > active list. > > Unfortunately to date I have been unable to reproduce this with a variety > of stress workloads on a 2G 32-bit KVM instance. It's not clear why as > the steps are similar to what was described. It means I've been unable to > determine if this series addresses the problem or not. I'm hoping they can > test and report back before these are merged to mmotm. What I have checked > is that a basic parallel DD workload completed successfully on the same > machine I used for the node-lru performance tests. I'll leave the other > tests running just in case anything interesting falls out. > > The series is in three basic parts; > > Patch 1 does not account for skipped pages as scanned. This avoids the pgdat > being prematurely marked unreclaimable > > Patches 2-4 add per-zone stats back in. The actual stats patch is different > to Minchan's as the original patch did not account for unevictable > LRU which would corrupt counters. The second two patches remove > approximations based on pgdat statistics. It's effectively a > revert of "mm, vmstat: remove zone and node double accounting by > approximating retries" but different LRU stats are used. This > is better than a full revert or a reworking of the series as > it preserves history of why the zone stats are necessary. > > If this work out, we may have to leave the double accounting in > place for now until an alternative cheap solution presents itself. > > Patch 5 rotates inactive/active lists for lowmem allocations. This is also > quite different to Minchan's patch as the original patch did not > account for memcg and would rotate if *any* eligible zone needed > rotation which may rotate excessively. The new patch considers > the ratio for all eligible zones which is more in line with > node-lru in general. > Now I tested and confirmed it works for me at the OOM point of view. IOW, I cannot see OOM kill any more. But note that I tested it without [1/5] which has a problem I mentioned in that thread. If you want to merge [1/5], please resend updated version but I doubt we need it at this moment.
