mm, page_alloc: print symbolic gfp_flags on allocation failure

It would be useful to translate gfp_flags into string representation
when printing in case of an allocation failure, especially as the flags
have been undergoing some changes recently and the script
./scripts/gfp-translate needs a matching source version to be accurate.

Example output:

  stapio: page allocation failure: order:9, mode:0x2080020(GFP_ATOMIC)
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/page_alloc.c

@@ -2695,9 +2695,8 @@ void warn_alloc_failed(gfp_t gfp_mask, unsigned int order, const char *fmt, ...)
 		va_end(args);
 	}
 
-	pr_warn("%s: page allocation failure: order:%u, mode:0x%x\n",
-		current->comm, order, gfp_mask);
-
+	pr_warn("%s: page allocation failure: order:%u, mode:%#x(%pGg)\n",
+		current->comm, order, gfp_mask, &gfp_mask);
 	dump_stack();
 	if (!should_suppress_show_mem())
 		show_mem(filter);