Messages in this thread | | | Date | Mon, 31 Oct 2011 16:28:33 +0100 | From | Oleg Nesterov <> | Subject | Re: [PATCH] oom: fix integer overflow of points in oom_badness |
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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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