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Groups > linux.kernel > #1227978
| From | Dave Hansen <dave.hansen@intel.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: 4.3-rc1 dirty page count underflow (cgroup-related?) |
| Date | 2015-09-18 17:00 +0200 |
| Message-ID | <qa5iQ-5JO-51@gated-at.bofh.it> (permalink) |
| References | <q9Vt8-eQ-1@gated-at.bofh.it> <q9X1T-2y9-1@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
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 from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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4.3-rc1 dirty page count underflow (cgroup-related?) Dave Hansen <dave.hansen@intel.com> - 2015-09-18 06:30 +0200
Re: 4.3-rc1 dirty page count underflow (cgroup-related?) Greg Thelen <gthelen@google.com> - 2015-09-18 08:10 +0200
Re: 4.3-rc1 dirty page count underflow (cgroup-related?) Greg Thelen <gthelen@google.com> - 2015-09-18 10:40 +0200
Re: 4.3-rc1 dirty page count underflow (cgroup-related?) Dave Hansen <dave.hansen@intel.com> - 2015-09-18 17:00 +0200
Re: 4.3-rc1 dirty page count underflow (cgroup-related?) Greg Thelen <gthelen@google.com> - 2015-09-21 10:10 +0200
Re: 4.3-rc1 dirty page count underflow (cgroup-related?) Michal Hocko <mhocko@kernel.org> - 2015-09-22 11:10 +0200
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