On Wed, 2017-03-08 at 10:21 +0100, Michal Hocko wrote: > > Could that create problems if we have many concurrent > > reclaimers? > > As the changelog mentions it might cause a premature oom killer > invocation theoretically. We could easily see that from the oom > report > by checking isolated counters. My testing didn't trigger that though > and I was hammering the page allocator path from many threads. > > I suspect some artificial tests can trigger that, I am not so sure > about > reasonabel workloads. If we see this happening though then the fix > would > be to resurrect my previous attempt to track NR_ISOLATED* per zone > and > use them in the allocator retry logic. I am not sure the workload in question is "artificial". A heavily forking (or multi-threaded) server running out of physical memory could easily get hundreds of tasks doing direct reclaim simultaneously. 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. I am perfectly fine with moving the retry logic up like you did, but think it may make sense to check the number of reclaimable pages if we have too many isolated pages, instead of risking a too-early OOM kill. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
