mm/page_alloc: correct return value when failing at preparing

If the array passed in is already partially populated, we should return
"nr_populated" even failing at preparing arguments stage.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Yanfei Xu <[email protected]>
Signed-off-by: Mel Gorman <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Author: Yanfei Xu

mm/page_alloc.c

@@ -5255,7 +5255,7 @@ unsigned long __alloc_pages_bulk(gfp_t gfp, int preferred_nid,
 	gfp &= gfp_allowed_mask;
 	alloc_gfp = gfp;
 	if (!prepare_alloc_pages(gfp, 0, preferred_nid, nodemask, &ac, &alloc_gfp, &alloc_flags))
-		return 0;
+		return nr_populated;
 	gfp = alloc_gfp;
 
 	/* Find an allowed local zone that meets the low watermark. */