On Thu 01-02-24 18:08:34, Liu Shixin wrote:
> When a task in memcg readaheads file pages, page_cache_ra_unbounded()
> will try to readahead nr_to_read pages. Even if the new allocated page
> fails to charge, page_cache_ra_unbounded() still tries to readahead
> next page. This leads to too much memory reclaim.
>
> Stop readahead if mem_cgroup_charge() fails, i.e. add_to_page_cache_lru()
> returns -ENOMEM.
>
> Signed-off-by: Liu Shixin <liushixin2@xxxxxxxxxx>
> Signed-off-by: Jinjiang Tu <tujinjiang@xxxxxxxxxx>
Makes sense. Feel free to add:
Reviewed-by: Jan Kara <jack@xxxxxxx>
Honza
> ---
> mm/readahead.c | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/mm/readahead.c b/mm/readahead.c
> index 23620c57c1225..cc4abb67eb223 100644
> --- a/mm/readahead.c
> +++ b/mm/readahead.c
> @@ -228,6 +228,7 @@ void page_cache_ra_unbounded(struct readahead_control *ractl,
> */
> for (i = 0; i < nr_to_read; i++) {
> struct folio *folio = xa_load(&mapping->i_pages, index + i);
> + int ret;
>
> if (folio && !xa_is_value(folio)) {
> /*
> @@ -247,9 +248,12 @@ void page_cache_ra_unbounded(struct readahead_control *ractl,
> folio = filemap_alloc_folio(gfp_mask, 0);
> if (!folio)
> break;
> - if (filemap_add_folio(mapping, folio, index + i,
> - gfp_mask) < 0) {
> +
> + ret = filemap_add_folio(mapping, folio, index + i, gfp_mask);
> + if (ret < 0) {
> folio_put(folio);
> + if (ret == -ENOMEM)
> + break;
> read_pages(ractl);
> ractl->_index++;
> i = ractl->_index + ractl->_nr_pages - index - 1;
> --
> 2.25.1
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
