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    SubjectRe: [PATCH] oom: fix integer overflow of points in oom_badness
    On 10/31, Frantisek Hrbata wrote:
    >
    > My understanding is that we may just change the type of points variable from int
    > to long and keep the current imho clearer(better readable) computation. There
    > should not be an overflow on 32bit and there is a plenty of space for 64bit.
    > If you like this solution better I will post the patch as v2.

    Up to maintainer, but personally I think the simple s/int/long/ looks better.
    Everything like get_mm_*/nr_ptes returns long.

    Anyway good catch. Imho stable needs the fix too.

    Cosmetic nit,

    > - points = get_mm_rss(p->mm) + p->mm->nr_ptes;
    > - points += get_mm_counter(p->mm, MM_SWAPENTS);
    > + points = (int)((get_mm_rss(p->mm) + get_mm_counter(p->mm, MM_SWAPENTS) +
    ^^^^^

    Why do we need the explicit typecast? It buys nothing and looks a bit confusing.

    And, if you prefer "int", perhaps something like

    - points *= 1000;
    - points /= totalpages;
    + /* avoid the possible overflow */
    + points = points * 1000L / totalpages;

    looks a bit more readable with the same effect. But I won't insist, this is
    up to you and David.

    Oleg.



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