Hello,
On Fri, Feb 27, 2015 at 11:37:18AM +0800, Wang, Yalin wrote:
> This patch add ClearPageDirty() to clear AnonPage dirty flag,
> the Anonpage mapcount must be 1, so that this page is only used by
> the current process, not shared by other process like fork().
> if not clear page dirty for this anon page, the page will never be
> treated as freeable.
In case of anonymous page, it has PG_dirty when VM adds it to
swap cache and clear it in clear_page_dirty_for_io. That's why
I added ClearPageDirty if we found it in swapcache.
What case am I missing? It would be better to understand if you
describe specific scenario.
Thanks.
>
> Signed-off-by: Yalin Wang <yalin.w...@sonymobile.com>
> ---
> mm/madvise.c | 15 +++++----------
> 1 file changed, 5 insertions(+), 10 deletions(-)
>
> diff --git a/mm/madvise.c b/mm/madvise.c
> index 6d0fcb8..257925a 100644
> --- a/mm/madvise.c
> +++ b/mm/madvise.c
> @@ -297,22 +297,17 @@ static int madvise_free_pte_range(pmd_t *pmd, unsigned
> long addr,
> continue;
>
> page = vm_normal_page(vma, addr, ptent);
> - if (!page)
> + if (!page || !PageAnon(page) || !trylock_page(page))
> continue;
>
> if (PageSwapCache(page)) {
> - if (!trylock_page(page))
> + if (!try_to_free_swap(page))
> continue;
> -
> - if (!try_to_free_swap(page)) {
> - unlock_page(page);
> - continue;
> - }
> -
> - ClearPageDirty(page);
> - unlock_page(page);
> }
>
> + if (page_mapcount(page) == 1)
> + ClearPageDirty(page);
> + unlock_page(page);
> /*
> * Some of architecture(ex, PPC) don't update TLB
> * with set_pte_at and tlb_remove_tlb_entry so for
> --
> 2.2.2
>
> --
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--
Kind regards,
Minchan Kim
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