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    SubjectRe: [RFC PATCH 5/8] hugetlb: change free_pool_huge_page to remove_pool_huge_page
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    On 3/24/21 1:40 AM, Michal Hocko wrote:
    > On Tue 23-03-21 18:03:07, Mike Kravetz wrote:
    > [...]
    >> Since you brought up cgroups ... what is your opinion on lock hold time
    >> in hugetlb_cgroup_css_offline? We could potentially be calling
    >> hugetlb_cgroup_move_parent for every hugetlb page while holding the lock
    >> with interrupts disabled.
    >
    > I am not familiar with hugetlb cgroup code TBH. But from a quick look
    > there is not much of heavy lifting there. If we find out that this is
    > really visible we can do the lock dance with cond_resched and retry with
    > the iteration again. Or is there any strong reason to process the list
    > in a single go?

    AFAICT, the primary reason for processing the list in a single go is
    that the lock protects the list. If you drop the lock, the list can
    change ...

    I have come up with a (not so pretty) way of processing the list in
    batches of pages. But, I dod not want to introduce that if there is no
    need. Perhaps just take a wait and see approach for now.

    I'll see if I can come up with some timing information to determine
    if/when we may have an issue.
    --
    Mike Kravetz

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