On Fri 20-06-14 12:33:47, Johannes Weiner wrote:
> shrink_zones() has a special branch to skip the all_unreclaimable()
> check during hibernation, because a frozen kswapd can't mark a zone
> unreclaimable.
>
> But ever since 6e543d5780e3 ("mm: vmscan: fix do_try_to_free_pages()
> livelock"), determining a zone to be unreclaimable is done by directly
> looking at its scan history and no longer relies on kswapd setting the
> per-zone flag.
>
> Remove this branch and let shrink_zones() check the reclaimability of
> the target zones regardless of hibernation state.
>
> Signed-off-by: Johannes Weiner <[email protected]>
This code is really tricky :/
But the patch looks good to me.
Acked-by: Michal Hocko <[email protected]>
> ---
> mm/vmscan.c | 8 --------
> 1 file changed, 8 deletions(-)
>
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 0f16ffe8eb67..19b5b8016209 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -2534,14 +2534,6 @@ out:
> if (sc->nr_reclaimed)
> return sc->nr_reclaimed;
>
> - /*
> - * As hibernation is going on, kswapd is freezed so that it can't mark
> - * the zone into all_unreclaimable. Thus bypassing all_unreclaimable
> - * check.
> - */
> - if (oom_killer_disabled)
> - return 0;
> -
> /* Aborted reclaim to try compaction? don't OOM, then */
> if (aborted_reclaim)
> return 1;
> --
> 2.0.0
>
--
Michal Hocko
SUSE Labs
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