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    Subject[PATCH 1/3] mm/mempolicy: apply cpuset limits to tasks using default policy
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    The nodemasks of non-default policies (pol->v) are calculated within
    the restriction of task->mems_allowed, while default policies are not.
    This may lead to improper results of mpol_misplaced(), since it can
    return a target node outside of current->mems_allowed for tasks using
    default policies. Although this is not a bug because migrating pages
    to that out-of-cpuset node will fail eventually due to sanity checks
    in page allocation, it still would be better to avoid such useless
    efforts.

    This patch also changes the behavior of autoNUMA a bit by showing
    a tendency to move pages inside mems_allowed for tasks using default
    policies, which is good for memory isolation.

    Signed-off-by: Abel Wu <wuyun.abel@bytedance.com>
    ---
    mm/mempolicy.c | 5 ++++-
    1 file changed, 4 insertions(+), 1 deletion(-)

    diff --git a/mm/mempolicy.c b/mm/mempolicy.c
    index d79fa299b70c..e0ae6997bbfb 100644
    --- a/mm/mempolicy.c
    +++ b/mm/mempolicy.c
    @@ -2516,7 +2516,10 @@ int mpol_misplaced(struct page *page, struct vm_area_struct *vma, unsigned long

    /* Migrate the page towards the node whose CPU is referencing it */
    if (pol->flags & MPOL_F_MORON) {
    - polnid = thisnid;
    + if (node_isset(thisnid, cpuset_current_mems_allowed))
    + polnid = thisnid;
    + else
    + polnid = node_random(&cpuset_current_mems_allowed);

    if (!should_numa_migrate_memory(current, page, curnid, thiscpu))
    goto out;
    --
    2.31.1
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