Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> writes:
> If we fail with a allocated hugepage, we need some effort to recover
> properly. So, it is better not to allocate a hugepage as much as possible.
> So move up anon_vma_prepare() which can be failed in OOM situation.
>
> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
>
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 2372f75..7e9a651 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -2520,6 +2520,17 @@ retry_avoidcopy:
> spin_unlock(&mm->page_table_lock);
>
> /*
> + * When the original hugepage is shared one, it does not have
> + * anon_vma prepared.
> + */
> + if (unlikely(anon_vma_prepare(vma))) {
> + page_cache_release(old_page);
> + /* Caller expects lock to be held */
> + spin_lock(&mm->page_table_lock);
> + return VM_FAULT_OOM;
> + }
> +
> + /*
> * If the process that created a MAP_PRIVATE mapping is about to
> * perform a COW due to a shared page count, attempt to satisfy
> * the allocation without using the existing reserves. The pagecache
> @@ -2578,18 +2589,6 @@ retry_avoidcopy:
> return VM_FAULT_SIGBUS;
> }
>
> - /*
> - * When the original hugepage is shared one, it does not have
> - * anon_vma prepared.
> - */
> - if (unlikely(anon_vma_prepare(vma))) {
> - page_cache_release(new_page);
> - page_cache_release(old_page);
> - /* Caller expects lock to be held */
> - spin_lock(&mm->page_table_lock);
> - return VM_FAULT_OOM;
> - }
> -
> copy_user_huge_page(new_page, old_page, address, vma,
> pages_per_huge_page(h));
> __SetPageUptodate(new_page);
> --
> 1.7.9.5
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