Re: [PATCH v2 02/12] mm/shmem: Use pagevec_lookup in shmem_unlock_mapping

From: Jan Kara
Date: Tue Sep 29 2020 - 04:28:32 EST


On Mon 14-09-20 14:00:32, Matthew Wilcox (Oracle) wrote:
> The comment shows that the reason for using find_get_entries() is now
> stale; find_get_pages() will not return 0 if it hits a consecutive run
> of swap entries, and I don't believe it has since 2011. pagevec_lookup()
> is a simpler function to use than find_get_pages(), so use it instead.
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>

Looks good to me. BTW, I think I've already reviewed this... You can add:

Reviewed-by: Jan Kara <jack@xxxxxxx>

Honza

> ---
> mm/shmem.c | 11 +----------
> 1 file changed, 1 insertion(+), 10 deletions(-)
>
> diff --git a/mm/shmem.c b/mm/shmem.c
> index 58bc9e326d0d..108931a6cc43 100644
> --- a/mm/shmem.c
> +++ b/mm/shmem.c
> @@ -840,7 +840,6 @@ unsigned long shmem_swap_usage(struct vm_area_struct *vma)
> void shmem_unlock_mapping(struct address_space *mapping)
> {
> struct pagevec pvec;
> - pgoff_t indices[PAGEVEC_SIZE];
> pgoff_t index = 0;
>
> pagevec_init(&pvec);
> @@ -848,16 +847,8 @@ void shmem_unlock_mapping(struct address_space *mapping)
> * Minor point, but we might as well stop if someone else SHM_LOCKs it.
> */
> while (!mapping_unevictable(mapping)) {
> - /*
> - * Avoid pagevec_lookup(): find_get_pages() returns 0 as if it
> - * has finished, if it hits a row of PAGEVEC_SIZE swap entries.
> - */
> - pvec.nr = find_get_entries(mapping, index,
> - PAGEVEC_SIZE, pvec.pages, indices);
> - if (!pvec.nr)
> + if (!pagevec_lookup(&pvec, mapping, &index))
> break;
> - index = indices[pvec.nr - 1] + 1;
> - pagevec_remove_exceptionals(&pvec);
> check_move_unevictable_pages(&pvec);
> pagevec_release(&pvec);
> cond_resched();
> --
> 2.28.0
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR