Re: [PATCH] mm/damon/paddr: fix pin page problem

[David Hildenbrand]

On 21.02.23 10:03, Andrew Yang wrote:
> From: "andrew.yang" <andrew.yang@xxxxxxxxxxxx>

Nit: I'd suggest a different subject

"mm/damon/paddr: fix missing put_page()"


Fixes: ?
Cc: stable ?


I think a patch from Willy is queued that converts this code into folios.

> damon_get_page() would always increase page _refcount and
> isolate_lru_page() would increase page _refcount if the page's lru
> flag is set.
>
> If a unevictable page isolated successfully, there will be two more
> _refcount. The one from isolate_lru_page() will be decreased in
> putback_lru_page(), but the other one from damon_get_page() will be
> left behind. This causes a pin page.
>
> Whatever the case, the _refcount from damon_get_page() should be
> decreased.
>
> Signed-off-by: andrew.yang <andrew.yang@xxxxxxxxxxxx>
> ---
>   mm/damon/paddr.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c
> index e1a4315c4be6..56d8abd08fb1 100644
> --- a/mm/damon/paddr.c
> +++ b/mm/damon/paddr.c
> @@ -223,8 +223,8 @@ static unsigned long damon_pa_pageout(struct damon_region *r)
>   			putback_lru_page(page);
>   		} else {
>   			list_add(&page->lru, &page_list);
> -			put_page(page);
>   		}
> +		put_page(page);
>   	}
>   	applied = reclaim_pages(&page_list);
>   	cond_resched();

--
Thanks,

David / dhildenb