mm: alloc_contig_range: demote pages busy message from warn to info

Having test_pages_isolated failure message as a warning confuses users
into thinking that it is more serious than it really is.  In reality, if
called via CMA, allocation will be retried so a single
test_pages_isolated failure does not prevent allocation from succeeding.

Demote the warning message to an info message and reformat it such that
the text "failed" does not appear and instead a less worrying "PFNS
busy" is used.

This message is trivially reproducible on a 10GB x86 machine on 3.16.y
kernels configured with CONFIG_DMA_CMA.

Signed-off-by: Michal Nazarewicz <[email protected]>
Cc: Laurent Pinchart <[email protected]>
Cc: Peter Hurley <[email protected]>
Cc: Minchan Kim <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Author: mina86

mm/page_alloc.c

@@ -6397,13 +6397,12 @@ int alloc_contig_range(unsigned long start, unsigned long end,
 
 	/* Make sure the range is really isolated. */
 	if (test_pages_isolated(outer_start, end, false)) {
-		pr_warn("alloc_contig_range test_pages_isolated(%lx, %lx) failed\n",
-		       outer_start, end);
+		pr_info("%s: [%lx, %lx) PFNs busy\n",
+			__func__, outer_start, end);
 		ret = -EBUSY;
 		goto done;
 	}
 
-
 	/* Grab isolated pages from freelists. */
 	outer_end = isolate_freepages_range(&cc, outer_start, end);
 	if (!outer_end) {