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src/slave/containerizer/mesos/isolators/cgroups/subsystems/memory.cpp Lines 266-270 (patched) <https://reviews.apache.org/r/57574/#comment241154> It's not clear to me how we ensure this invariant with the code below. Maybe just updating the comment is enough to clear things up, but when I look at thsi code, it's not obvious to me how this invariant is mantained. Is the assumption that `memory.limit_in_bytes` and `memory.memsw.limit_in_bytes` are initially equal? Is it also assumed that `currentLimit` will only ever be greater than or equal to the `initialLimit` the first time through this function. If so, why? What keeps us from passing a `limit` to this function that exceeds `initialLimit` such that the case for `(currentLimit.get() >= initialLimit)` gets invoked more than just the first time this function is called? Independent of that, I don't understand how we can ensure that `memory.limit_in_bytes` always remains less than or equal `memory.memsw.limit_in_bytes` in the case of `(limit > currentLimit.get())`. If the new `limit` is greater than the `currentLimit` and we set `memory.memsw.limit_in_bytes` before we set `memory.limit_in_bytes`, doesn't that explicitly violate this invariant? Maybe I'm missing something. - Kevin Klues On March 14, 2017, 12:04 a.m., Jie Yu wrote: > > ----------------------------------------------------------- > This is an automatically generated e-mail. To reply, visit: > https://reviews.apache.org/r/57574/ > ----------------------------------------------------------- > > (Updated March 14, 2017, 12:04 a.m.) > > > Review request for mesos, Benjamin Mahler, haosdent huang, Ian Downes, and > Kevin Klues. > > > Bugs: MESOS-7237 > https://issues.apache.org/jira/browse/MESOS-7237 > > > Repository: mesos > > > Description > ------- > > This addressed the bug we saw in MESOS-7237. Linux kernel will ensure > cgroup memory+swap limit (i.e., 'memory.memsw.limit_in_bytes') is always > no less than the memory limit ('memory.limit_in_bytes'). Prior to this > patch, the memory subsystem in the cgroups isolator is buggy because > memory+swap limit is always changed after the memory limit. This will > cause EINVAL if we increase the memory limit of the container. > > > Diffs > ----- > > src/slave/containerizer/mesos/isolators/cgroups/subsystems/memory.cpp > 009e996add25e43e8989600a58b38f2cc88a5d11 > > > Diff: https://reviews.apache.org/r/57574/diff/1/ > > > Testing > ------- > > sudo make check > > > Thanks, > > Jie Yu > >
