On Tue, 31 Mar 2015 01:45:55 +0000 Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx> wrote:
> Currently when a process accesses to hugetlb range protected with PROTNONE,
> unexpected COWs are triggered, which finally put hugetlb subsystem into
> broken/uncontrollable state, where for example h->resv_huge_pages is subtracted
> too much and wrapped around to a very large number, and free hugepage pool
> is no longer maintainable.
>
> This patch simply stops changing protection for vma(VM_HUGETLB) to fix the
> problem. And this also allows us to avoid useless overhead of minor faults.
>
> ...
>
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -2161,8 +2161,10 @@ void task_numa_work(struct callback_head *work)
> vma = mm->mmap;
> }
> for (; vma; vma = vma->vm_next) {
> - if (!vma_migratable(vma) || !vma_policy_mof(vma))
> + if (!vma_migratable(vma) || !vma_policy_mof(vma) ||
> + is_vm_hugetlb_page(vma)) {
> continue;
> + }
>
> /*
> * Shared library pages mapped by multiple processes are not
Which kernel version(s) need this patch?
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