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From: Dev Jain <dev.jain@arm.com>
To: akpm@linux-foundation.org,
	shuah@kernel.org
Cc: linux-mm@kvack.org,
	linux-kselftest@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	Anshuman.Khandual@arm.com,
	Dev Jain <dev.jain@arm.com>
Subject: [PATCH] selftests/mm: compaction_test: Fix trivial test pass on Aarch64 when nr_hugepages = 0
Date: Mon, 13 May 2024 13:58:42 +0530
Message-Id: <20240513082842.4117782-1-dev.jain@arm.com>
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Currently, if at runtime we are not able to allocate a huge page, the
test will trivially pass on Aarch64 due to no exception being raised on
division by zero while computing compaction_index. Fix that by checking
for nr_hugepages == 0. Anyways, in general, avoid a division by zero by
exiting the program beforehand. While at it, fix a typo.

Signed-off-by: Dev Jain <dev.jain@arm.com>
---
 tools/testing/selftests/mm/compaction_test.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/mm/compaction_test.c b/tools/testing/selftests/mm/compaction_test.c
index 533999b6c284..df1b76f9c734 100644
--- a/tools/testing/selftests/mm/compaction_test.c
+++ b/tools/testing/selftests/mm/compaction_test.c
@@ -134,6 +134,10 @@ int check_compaction(unsigned long mem_free, unsigned int hugepage_size)
 
 	/* We should have been able to request at least 1/3 rd of the memory in
 	   huge pages */
+	if (!atoi(nr_hugepages)) {
+		ksft_print_msg("ERROR: No memory is available as huge pages\n");
+		goto close_fd;
+	}
 	compaction_index = mem_free/(atoi(nr_hugepages) * hugepage_size);
 
 	lseek(fd, 0, SEEK_SET);
@@ -149,7 +153,7 @@ int check_compaction(unsigned long mem_free, unsigned int hugepage_size)
 		       atoi(nr_hugepages));
 
 	if (compaction_index > 3) {
-		ksft_print_msg("ERROR: Less that 1/%d of memory is available\n"
+		ksft_print_msg("ERROR: Less than 1/%d of memory is available\n"
 			       "as huge pages\n", compaction_index);
 		goto close_fd;
 	}
-- 
2.39.2