On 11/23/18 12:45 PM, Mel Gorman wrote:
> This is a preparation patch that copies the GFP flag __GFP_KSWAPD_RECLAIM
> into alloc_flags. This is a preparation patch only that avoids having to
> pass gfp_mask through a long callchain in a future patch.
>
> Note that the setting in the fast path happens in alloc_flags_nofragment()
> and it may be claimed that this has nothing to do with ALLOC_NO_FRAGMENT.
> That's true in this patch but is not true later so it's done now for
> easier review to show where the flag needs to be recorded.
>
> No functional change.
>
> Signed-off-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
Small bug below:
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -3278,10 +3278,15 @@ static bool zone_allows_reclaim(struct zone *local_zone, struct zone *zone)
> * fragmentation between the Normal and DMA32 zones.
> */
> static inline unsigned int
> -alloc_flags_nofragment(struct zone *zone)
> +alloc_flags_nofragment(struct zone *zone, gfp_t gfp_mask)
> {
> + unsigned int alloc_flags = 0;
> +
> + if (gfp_mask & __GFP_KSWAPD_RECLAIM)
> + alloc_flags |= ALLOC_KSWAPD;
> +
> if (zone_idx(zone) != ZONE_NORMAL)
> - return 0;
> + goto out;
>
> /*
> * If ZONE_DMA32 exists, assume it is the one after ZONE_NORMAL and
> @@ -3290,13 +3295,14 @@ alloc_flags_nofragment(struct zone *zone)
> */
> BUILD_BUG_ON(ZONE_NORMAL - ZONE_DMA32 != 1);
> if (nr_online_nodes > 1 && !populated_zone(--zone))
> - return 0;
> + goto out;
>
> - return ALLOC_NOFRAGMENT;
> +out:
> + return alloc_flags;
> }
> #else
> static inline unsigned int
> -alloc_flags_nofragment(struct zone *zone)
> +alloc_flags_nofragment(struct zone *zone, gfp_t gfp_mask)
> {
> return 0;
The !CONFIG_ZONE_DMA32 version should still set ALLOC_KSWAPD, right?
> }
> @@ -3939,6 +3945,9 @@ gfp_to_alloc_flags(gfp_t gfp_mask)
> } else if (unlikely(rt_task(current)) && !in_interrupt())
> alloc_flags |= ALLOC_HARDER;
>
> + if (gfp_mask & __GFP_KSWAPD_RECLAIM)
> + alloc_flags |= ALLOC_KSWAPD;
> +
> #ifdef CONFIG_CMA
> if (gfpflags_to_migratetype(gfp_mask) == MIGRATE_MOVABLE)
> alloc_flags |= ALLOC_CMA;
