libcontainer/cgroups: do not enable kmem on broken kernels #1920
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Wondering if it should be a compile time option, so that packagers for a specific distro can enable/disable it |
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
Commit fe898e7 (PR opencontainers#1350) enables kernel memory accounting for all cgroups created by libcontainer even if kmem limit is not configured. Kernel memory accounting is known to be broken in RHEL7 kernels, including the latest RHEL 7.5 kernel. It does not support reclaim and can lead to kernel oopses while removing cgroup (merging it with its parent). Unconditionally enabling kmem acct on RHEL7 leads to bugs: * opencontainers#1725 * kubernetes/kubernetes#61937 * moby/moby#29638 I am not aware of any good way to figure out whether the kernel memory accounting in the given kernel is working or broken. For the lack of a better way, let's check if the running kernel is RHEL7, and disable initial setting of kmem. Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
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cc @mrunalp |
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Apparently the kernel bug(s) we work around here are not fixed in latest-n-greatest RHEL7.6 kernels (see latest comments in https://bugzilla.redhat.com/show_bug.cgi?id=1507149). |
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I prefer #1921 and have LGTM'ed it. Thanks! |
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NACK. I prefer #1921 as well. |
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Closed in favor of #1921 |
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Commit fe898e7 (PR #1350) enables kernel memory accounting for all cgroups created by libcontainer even if kmem limit is not configured.
Kernel memory accounting is known to be broken in RHEL7 kernels,
including the latest RHEL 7.5 kernel. It does not support reclaim
and can lead to kernel oopses while removing cgroup (merging it
with its parent). Unconditionally enabling kmem acct on RHEL7
leads to bugs:
I am not aware of any good way to figure out whether the kernel
memory accounting in the given kernel is working or broken.
For the lack of a better way, let's check if the running kernel
is RHEL7, and disable initial setting of kmem.
Alternative to #1898