[RFC 1/2] Try to use HighAtomic if try to alloc umovable page that order is not 0

[Hui Zhu]

The page add a new condition to let gfp_to_alloc_flags return
alloc_flags with ALLOC_HARDER if the order is not 0 and migratetype is
MIGRATE_UNMOVABLE.

Then alloc umovable page that order is not 0 will try to use HighAtomic.

Signed-off-by: Hui Zhu <zhuhui@xxxxxxxxxx>
---
 mm/page_alloc.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index c841af8..b54e94a 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3642,7 +3642,7 @@ static void wake_all_kswapds(unsigned int order, const struct alloc_context *ac)
 }
 
 static inline unsigned int
-gfp_to_alloc_flags(gfp_t gfp_mask)
+gfp_to_alloc_flags(gfp_t gfp_mask, int order, int migratetype)
 {
 	unsigned int alloc_flags = ALLOC_WMARK_MIN | ALLOC_CPUSET;
 
@@ -3671,6 +3671,8 @@ static void wake_all_kswapds(unsigned int order, const struct alloc_context *ac)
 		alloc_flags &= ~ALLOC_CPUSET;
 	} else if (unlikely(rt_task(current)) && !in_interrupt())
 		alloc_flags |= ALLOC_HARDER;
+	else if (order > 0 && migratetype == MIGRATE_UNMOVABLE)
+		alloc_flags |= ALLOC_HARDER;
 
 #ifdef CONFIG_CMA
 	if (gfpflags_to_migratetype(gfp_mask) == MIGRATE_MOVABLE)
@@ -3903,7 +3905,7 @@ bool gfp_pfmemalloc_allowed(gfp_t gfp_mask)
 	 * kswapd needs to be woken up, and to avoid the cost of setting up
 	 * alloc_flags precisely. So we do that now.
 	 */
-	alloc_flags = gfp_to_alloc_flags(gfp_mask);
+	alloc_flags = gfp_to_alloc_flags(gfp_mask, order, ac->migratetype);
 
 	/*
 	 * We need to recalculate the starting point for the zonelist iterator
-- 
1.9.1