> > > * tip-bot for Kan Liang <tipbot@xxxxxxxxx> wrote: > > > --- a/kernel/events/core.c > > +++ b/kernel/events/core.c > > @@ -4446,7 +4446,7 @@ static int perf_mmap(struct file *file, struct > vm_area_struct *vma) > > * If we have rb pages ensure they're a power-of-two number, so > we > > * can do bitmasks instead of modulo. > > */ > > - if (!is_power_of_2(nr_pages)) > > + if (nr_pages != 0 && !is_power_of_2(nr_pages)) > > return -EINVAL; > > Hm, what does is_power_of_2(0) return? It should return 0, because 0 is > not a power of 2! > > and if it's fixed to return 0, then the check should properly be something > like: > > if (!nr_pages || !is_power_of_2(nr_pages)) > > or so? nr_pages == 0 is valid, we cannot return -EINVAL. Because vma_size = vma->vm_end - vma->vm_start; nr_pages = (vma_size / PAGE_SIZE) - 1; So here we only want to check is_power_of_2 when the pages > 1 (or nr_pages > 0). Thanks, Kan > > Thanks, > > Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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