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    Subject[PATCH 0/3] mm: memcontrol: recursive memory protection
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    The current memory.low (and memory.min) semantics require protection
    to be assigned to a cgroup in an untinterrupted chain from the
    top-level cgroup all the way to the leaf.

    In practice, we want to protect entire cgroup subtrees from each other
    (system management software vs. workload), but we would like the VM to
    balance memory optimally *within* each subtree, without having to make
    explicit weight allocations among individual components. The current
    semantics make that impossible.

    This patch series extends memory.low/min such that the knobs apply
    recursively to the entire subtree. Users can still assign explicit
    protection to subgroups, but if they don't, the protection set by the
    parent cgroup will be distributed dynamically such that children
    compete freely - as if no memory control were enabled inside the
    subtree - but enjoy protection from neighboring trees.

    Patch #1 fixes an existing bug that can give a cgroup tree more
    protection than it should receive as per ancestor configuration.

    Patch #2 simplifies and documents the existing code to make it easier
    to reason about the changes in the next patch.

    Patch #3 finally implements recursive memory protection semantics.

    Because of a risk of regressing legacy setups, the new semantics are
    hidden behind a cgroup2 mount option, 'memory_recursiveprot'.

    More details in patch #3.

    Documentation/admin-guide/cgroup-v2.rst | 11 ++
    include/linux/cgroup-defs.h | 5 +
    kernel/cgroup/cgroup.c | 17 ++-
    mm/memcontrol.c | 241 +++++++++++++++++++-----------
    mm/page_counter.c | 12 +-
    5 files changed, 190 insertions(+), 96 deletions(-)


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