mm: let page allocation slowpath retry 'order' times

In an effort to prevent premature page allocation failures, retry
allocations in the slow path for up to 'order' times if retries
are allowed.

Orabug: 31295499

Signed-off-by: Mike Kravetz <[email protected]>
Reviewed-by: Khalid Aziz <[email protected]>
Signed-off-by: Brian Maly <[email protected]>

Author: mjkravetz

mm/page_alloc.c

@@ -2356,8 +2356,8 @@ void warn_alloc_failed(gfp_t gfp_mask, int order, const char *fmt, ...)
 
 static inline int
 should_alloc_retry(gfp_t gfp_mask, unsigned int order,
-				unsigned long did_some_progress,
-				unsigned long pages_reclaimed)
+			unsigned long did_some_progress,
+			unsigned long pages_reclaimed, int *alloc_retries)
 {
 	/* Do not loop if specifically requested */
 	if (gfp_mask & __GFP_NORETRY)
@@ -2393,6 +2393,17 @@ should_alloc_retry(gfp_t gfp_mask, unsigned int order,
 	if (gfp_mask & __GFP_REPEAT && pages_reclaimed < (1 << order))
 		return 1;
 
+	/*
+	 * We know __GFP_NORETRY is not set, so we are allowed to retry.
+	 * As long as we are making progress, retry at least order times
+	 * before giving up.
+	 * NOTE - alloc_retries only comes into play in this 'last chance'
+	 * retry scenario.
+	 */
+	(*alloc_retries)++;
+	if (did_some_progress && *alloc_retries <= order)
+		return 1;
+
 	return 0;
 }
 
@@ -2686,6 +2697,7 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
 	enum migrate_mode migration_mode = MIGRATE_ASYNC;
 	bool deferred_compaction = false;
 	int contended_compaction = COMPACT_CONTENDED_NONE;
+	int alloc_retries = 0;
 
 	/*
 	 * In the slowpath, we sanity check order to avoid ever trying to
@@ -2821,7 +2833,7 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
 	/* Check if we should retry the allocation */
 	pages_reclaimed += did_some_progress;
 	if (should_alloc_retry(gfp_mask, order, did_some_progress,
-						pages_reclaimed)) {
+					pages_reclaimed, &alloc_retries)) {
 		/*
 		 * If we fail to make progress by freeing individual
 		 * pages, but the allocation wants us to keep going,