linux-kernel - [PATCH v3 4/8] selftests/mm: Fix thuge-gen test bugs

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Message-Id: <20230724082522.1202616-5-ryan.roberts@arm.com>
Date:   Mon, 24 Jul 2023 09:25:18 +0100
From:   Ryan Roberts <ryan.roberts@....com>
To:     "Andrew Morton" <akpm@...ux-foundation.org>,
        "Shuah Khan" <shuah@...nel.org>,
        Jérôme Glisse <jglisse@...hat.com>,
        "David Hildenbrand" <david@...hat.com>,
        "Mark Brown" <broonie@...nel.org>,
        "John Hubbard" <jhubbard@...dia.com>,
        "Florent Revest" <revest@...omium.org>,
        "Peter Xu" <peterx@...hat.com>
Cc:     Ryan Roberts <ryan.roberts@....com>, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, linux-kselftest@...r.kernel.org
Subject: [PATCH v3 4/8] selftests/mm: Fix thuge-gen test bugs

thuge-gen was previously only munmapping part of the mmapped buffer,
which caused us to run out of 1G huge pages for a later part of the
test. Fix this by munmapping the whole buffer. Based on the code, it
looks like a typo rather than an intention to keep some of the buffer
mapped.

thuge-gen was also calling mmap with SHM_HUGETLB flag (bit 11 set),
which is actually MAP_DENYWRITE in mmap context. The man page says this
flag is ignored in modern kernels. I'm pretty sure from the context that
the author intended to pass the MAP_HUGETLB flag so I've fixed that up
too.

Reviewed-by: David Hildenbrand <david@...hat.com>
Signed-off-by: Ryan Roberts <ryan.roberts@....com>
---
 tools/testing/selftests/mm/thuge-gen.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/mm/thuge-gen.c b/tools/testing/selftests/mm/thuge-gen.c
index 380ab5f0a534..16ed4dfa7359 100644
--- a/tools/testing/selftests/mm/thuge-gen.c
+++ b/tools/testing/selftests/mm/thuge-gen.c
@@ -139,7 +139,7 @@ void test_mmap(unsigned long size, unsigned flags)
 		before, after, before - after, size);
 	assert(size == getpagesize() || (before - after) == NUM_PAGES);
 	show(size);
-	err = munmap(map, size);
+	err = munmap(map, size * NUM_PAGES);
 	assert(!err);
 }
 
@@ -222,7 +222,7 @@ int main(void)
 		test_mmap(ps, MAP_HUGETLB | arg);
 	}
 	printf("Testing default huge mmap\n");
-	test_mmap(default_hps, SHM_HUGETLB);
+	test_mmap(default_hps, MAP_HUGETLB);
 
 	puts("Testing non-huge shmget");
 	test_shmget(getpagesize(), 0);
-- 
2.25.1