Re: [PATCH 2/3 -mmotm-2009-12-10-17-19] Count zero page as file_rss

Minchan Kim
2009-12-28T10:24:57Z

I missed Hugh.

Minchan Kim wrote:
> Long time ago, we counted zero page as file_rss.
> But after reinstanted zero page, we don't do it.
> It means rss of process would be smaller than old.
>
> It could chage OOM victim selection.
>
> Kame reported following as
> "Before starting zero-page works, I checked "questions" in lkml and
> found some reports that some applications start to go OOM after zero-page
> removal.
>
> For me, I know one of my customer's application depends on behavior of
> zero page (on RHEL5). So, I tried to add again it before RHEL6 because
> I think removal of zero-page corrupts compatibility."
>
> So how about adding zero page as file_rss again for compatibility?
>
> Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
> ---
> mm/memory.c | 7 +++++--
> 1 files changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/mm/memory.c b/mm/memory.c
> index 3743fb5..a4ba271 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -1995,6 +1995,7 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
> int reuse = 0, ret = 0;
> int page_mkwrite = 0;
> struct page *dirty_page = NULL;
> + int zero_pfn = 0;
>
> old_page = vm_normal_page(vma, address, orig_pte);
> if (!old_page) {
> @@ -2117,7 +2118,8 @@ gotten:
> if (unlikely(anon_vma_prepare(vma)))
> goto oom;
>
> - if (is_zero_pfn(pte_pfn(orig_pte))) {
> + zero_pfn = is_zero_pfn(pte_pfn(orig_pte));
> + if (zero_pfn) {
> new_page = alloc_zeroed_user_highpage_movable(vma, address);
> if (!new_page)
> goto oom;
> @@ -2147,7 +2149,7 @@ gotten:
> */
> page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
> if (likely(pte_same(*page_table, orig_pte))) {
> - if (old_page) {
> + if (old_page || zero_pfn) {
> if (!PageAnon(old_page)) {
> dec_mm_counter(mm, file_rss);
> inc_mm_counter(mm, anon_rss);
> @@ -2650,6 +2652,7 @@ static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
> spin_lock(ptl);
> if (!pte_none(*page_table))
> goto unlock;
> + inc_mm_counter(mm, file_rss);
> goto setpte;
> }
>