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Commit 0a79cdad authored by Mel Gorman's avatar Mel Gorman Committed by Linus Torvalds
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mm: use alloc_flags to record if kswapd can wake 

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.

[mgorman@techsingularity.net: ALLOC_KSWAPD flag needs to be applied in the !CONFIG_ZONE_DMA32 case]
  Link: http://lkml.kernel.org/r/20181126143503.GO23260@techsingularity.net
Link: http://lkml.kernel.org/r/20181123114528.28802-4-mgorman@techsingularity.net


Signed-off-by: default avatarMel Gorman <mgorman@techsingularity.net>
Reviewed-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zi Yan <zi.yan@cs.rutgers.edu>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent a9214443

mm/internal.h

+1 −0
Original line number Diff line number Diff line
@@ -499,6 +499,7 @@ 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;

mm/page_alloc.c

+18 −15
Original line number Diff line number Diff line
@@ -3268,7 +3268,6 @@ static bool zone_allows_reclaim(struct zone *local_zone, struct zone *zone) 
}

#endif	/* CONFIG_NUMA */



#ifdef CONFIG_ZONE_DMA32

/*

 * The restriction on ZONE_DMA32 as being a suitable zone to use to avoid

 * fragmentation is subtle. If the preferred zone was HIGHMEM then
@@ -3278,10 +3277,16 @@ 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;



#ifdef CONFIG_ZONE_DMA32

	if (zone_idx(zone) != ZONE_NORMAL)

		return 0;

		goto out;



	/*

	 * If ZONE_DMA32 exists, assume it is the one after ZONE_NORMAL and
@@ -3290,17 +3295,12 @@ 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;

}

#else

static inline unsigned int

alloc_flags_nofragment(struct zone *zone)

{

	return 0;

out:

#endif /* CONFIG_ZONE_DMA32 */

	return alloc_flags;

}

#endif



/*

 * get_page_from_freelist goes through the zonelist trying to allocate
@@ -3939,6 +3939,9 @@ 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 +4173,7 @@ __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 +4231,7 @@ __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 +4454,7 @@ __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);