On 09/17/2015 11:09 PM, Greg Thelen wrote: > I'm not denying the issue, bug the WARNING splat isn't necessarily > catching a problem. The corresponding code comes from your debug patch: > + WARN_ONCE(__this_cpu_read(memcg->stat->count[MEM_CGROUP_STAT_DIRTY]) > (1UL<<30), "MEM_CGROUP_STAT_DIRTY bogus"); > > This only checks a single cpu's counter, which can be negative. The sum > of all counters is what matters. > Imagine: > cpu1) dirty page: inc > cpu2) clean page: dec > The sum is properly zero, but cpu2 is -1, which will trigger the WARN. > > I'll look at the code and also see if I can reproduce the failure using > mem_cgroup_read_stat() for all of the new WARNs. D'oh. I'll replace those with the proper mem_cgroup_read_stat() and test with your patch to see if anything still triggers. > Did you notice if the global /proc/meminfo:Dirty count also underflowed? It did not underflow. It was one of the first things I looked at and it looked fine, went down near 0 at 'sync', etc... -- 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>