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    SubjectRe: [BUG] set_mempolicy(MPOL_INTERLEAV) cause kernel panic
    From
    2009/07/25 12:15 に KAMEZAWA Hiroyuki<kamezawa.hiroyu@jp.fujitsu.com> さんは書きました:
    > KAMEZAWA Hiroyuki wrote:
    >> KAMEZAWA Hiroyuki wrote:
    >> Then, here is a much easier fix. for trusting cpuset more.
    >>
    > just a memo about memory hotplug
    >
    > _Direct_ use of task->mems_allowed is only in cpuset and mempolicy.
    > If no policy is used, it's not checked.
    > (See alloc_pages_current())
    >
    > memory hotplug's notifier just updates top_cpuset's mems_allowed.
    > But it doesn't update each task's ones.
    > Then, task's bahavior is
    >
    > - tasks which don't use mempolicy will use all nodes, N_HIGH_MEMORY.
    > - tasks under cpuset will be controlled under their own cpuset.
    > - tasks under mempolicy will use their own policy.
    > but no new policy is re-calculated and, then, no new mask.
    >
    > Now, even if all memory on nodes a removed, pgdat just remains.
    > Then, cpuset/mempolicy will never access NODE_DATA(nid) which is NULL.

    Umm..
    I don't think this is optimal behavior. but if hotplug guys agree
    this, I agree this too.

    Thanks.


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