Re: [PATCH 3/7] vmscan: synchrounous lumpy reclaim use lock_page()instead trylock_page()

From: Minchan Kim
Date: Thu Aug 05 2010 - 10:17:20 EST


On Thu, Aug 05, 2010 at 03:13:39PM +0900, KOSAKI Motohiro wrote:
> When synchrounous lumpy reclaim, there is no reason to give up to
> reclaim pages even if page is locked. We use lock_page() instead
> trylock_page() in this case.
>
> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
> ---
> mm/vmscan.c | 4 +++-
> 1 files changed, 3 insertions(+), 1 deletions(-)
>
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 1cdc3db..833b6ad 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -665,7 +665,9 @@ static unsigned long shrink_page_list(struct list_head *page_list,
> page = lru_to_page(page_list);
> list_del(&page->lru);
>
> - if (!trylock_page(page))
> + if (sync_writeback == PAGEOUT_IO_SYNC)
> + lock_page(page);
> + else if (!trylock_page(page))
> goto keep;
>
> VM_BUG_ON(PageActive(page));
> --
> 1.6.5.2
>
>
>

Hmm. We can make sure lumpy already doesn't select the page locked?
I mean below scenario.

LRU head -> page A -> page B -> LRU tail

lock_page(page A)
some_function()
direct reclaim
select victim page B
enter lumpy mode
select victim page A as well as page B
shrink_page_list
lock_page(page A)


--
Kind regards,
Minchan Kim
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