On Tue 06-09-16 15:52:55, Vlastimil Babka wrote:
> Commit 6b4e3181d7bd ("mm, oom: prevent premature OOM killer invocation for high
> order request") was intended as a quick fix of OOM regressions for 4.8 and
> stable 4.7.x kernels. For a better long-term solution, we still want to
> consider compaction feedback, which should be possible after some more
> improvements in the following patches.
>
> This reverts commit 6b4e3181d7bd5ca5ab6f45929e4a5ffa7ab4ab7f.
>
> Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
> Cc: Michal Hocko <mhocko@xxxxxxxxxx>
> Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
> Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
> Cc: David Rientjes <rientjes@xxxxxxxxxx>
> Cc: Rik van Riel <riel@xxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
> ---
> mm/page_alloc.c | 51 +++++++++++++++++++++++++++++++++++++++++++++++++--
> 1 file changed, 49 insertions(+), 2 deletions(-)
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index ee3997859f14..1df7694f4ec7 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -3158,6 +3158,54 @@ __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
> return NULL;
> }
>
> +static inline bool
> +should_compact_retry(struct alloc_context *ac, int order, int alloc_flags,
> + enum compact_result compact_result,
> + enum compact_priority *compact_priority,
> + int compaction_retries)
> +{
> + int max_retries = MAX_COMPACT_RETRIES;
> +
> + if (!order)
> + return false;
> +
> + /*
> + * compaction considers all the zone as desperately out of memory
> + * so it doesn't really make much sense to retry except when the
> + * failure could be caused by insufficient priority
> + */
> + if (compaction_failed(compact_result)) {
> + if (*compact_priority > MIN_COMPACT_PRIORITY) {
> + (*compact_priority)--;
> + return true;
> + }
> + return false;
> + }
> +
> + /*
> + * make sure the compaction wasn't deferred or didn't bail out early
> + * due to locks contention before we declare that we should give up.
> + * But do not retry if the given zonelist is not suitable for
> + * compaction.
> + */
> + if (compaction_withdrawn(compact_result))
> + return compaction_zonelist_suitable(ac, order, alloc_flags);
> +
> + /*
> + * !costly requests are much more important than __GFP_REPEAT
> + * costly ones because they are de facto nofail and invoke OOM
> + * killer to move on while costly can fail and users are ready
> + * to cope with that. 1/4 retries is rather arbitrary but we
> + * would need much more detailed feedback from compaction to
> + * make a better decision.
> + */
> + if (order > PAGE_ALLOC_COSTLY_ORDER)
> + max_retries /= 4;
> + if (compaction_retries <= max_retries)
> + return true;
> +
> + return false;
> +}
> #else
> static inline struct page *
> __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
> @@ -3168,8 +3216,6 @@ __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
> return NULL;
> }
>
> -#endif /* CONFIG_COMPACTION */
> -
> static inline bool
> should_compact_retry(struct alloc_context *ac, unsigned int order, int alloc_flags,
> enum compact_result compact_result,
> @@ -3196,6 +3242,7 @@ should_compact_retry(struct alloc_context *ac, unsigned int order, int alloc_fla
> }
> return false;
> }
> +#endif /* CONFIG_COMPACTION */
>
> /* Perform direct synchronous page reclaim */
> static int
> --
> 2.9.3
--
Michal Hocko
SUSE Labs
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