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Subject[PATCH 3/5] mm: Use alloc_flags to record if kswapd can wake
Date
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@techsingularity.net>
---
mm/internal.h | 1 +
mm/page_alloc.c | 25 +++++++++++++++++--------
2 files changed, 18 insertions(+), 8 deletions(-)

diff --git a/mm/internal.h b/mm/internal.h
index 544355156c92..be826ee9dc7f 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -489,6 +489,7 @@ unsigned long reclaim_clean_pages_from_list(struct zone *zone,
#else
#define ALLOC_NOFRAGMENT 0x0
#endif
+#define ALLOC_KSWAPD 0x200 /* allow waking of kswapd */

enum ttu_flags;
struct tlbflush_unmap_batch;
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 4ba84cd2977a..e44eb68744ed 100644
--- 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;
}
@@ -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;
@@ -4170,7 +4179,7 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
if (!ac->preferred_zoneref->zone)
goto nopage;

- if (gfp_mask & __GFP_KSWAPD_RECLAIM)
+ if (alloc_flags & ALLOC_KSWAPD)
wake_all_kswapds(order, gfp_mask, ac);

/*
@@ -4228,7 +4237,7 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,

retry:
/* Ensure kswapd doesn't accidentally go to sleep as long as we loop */
- if (gfp_mask & __GFP_KSWAPD_RECLAIM)
+ if (alloc_flags & ALLOC_KSWAPD)
wake_all_kswapds(order, gfp_mask, ac);

reserve_flags = __gfp_pfmemalloc_flags(gfp_mask);
@@ -4451,7 +4460,7 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order, int preferred_nid,
* Forbid the first pass from falling back to types that fragment
* memory until all local zones are considered.
*/
- alloc_flags |= alloc_flags_nofragment(ac.preferred_zoneref->zone);
+ alloc_flags |= alloc_flags_nofragment(ac.preferred_zoneref->zone, gfp_mask);

/* First allocation attempt */
page = get_page_from_freelist(alloc_mask, order, alloc_flags, &ac);
--
2.16.4
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