mm/madvise: pass return code of memory_failure() to userspace

Currently the return value of memory_failure() is not passed to
userspace when madvise(MADV_HWPOISON) is used.  This is inconvenient for
test programs that want to know the result of error handling.  So let's
return it to the caller as we already do in the MADV_SOFT_OFFLINE case.
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Chen Gong <gong.chen@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/madvise.c

@@ -555,8 +555,9 @@ static int madvise_hwpoison(int bhv, unsigned long start, unsigned long end)
 		}
 		pr_info("Injecting memory failure for page %#lx at %#lx\n",
 		       page_to_pfn(p), start);
-		/* Ignore return value for now */
-		memory_failure(page_to_pfn(p), 0, MF_COUNT_INCREASED);
+		ret = memory_failure(page_to_pfn(p), 0, MF_COUNT_INCREASED);
+		if (ret)
+			return ret;
 	}
 	return 0;
 }