linux-kernel - [patch 2/2] mm, selftests: test return value of munmap for MAP

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Message-ID: <alpine.DEB.2.10.1503261623280.20009@chino.kir.corp.google.com>
Date:	Thu, 26 Mar 2015 16:23:55 -0700 (PDT)
From:	David Rientjes <rientjes@...gle.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
cc:	Jonathan Corbet <corbet@....net>,
	Davide Libenzi <davidel@...ilserver.org>,
	Luiz Capitulino <lcapitulino@...hat.com>,
	Shuah Khan <shuahkh@....samsung.com>,
	Hugh Dickins <hughd@...gle.com>,
	Andrea Arcangeli <aarcange@...hat.com>,
	Joern Engel <joern@...fs.org>,
	Jianguo Wu <wujianguo@...wei.com>,
	Eric B Munson <emunson@...mai.com>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, linux-api@...r.kernel.org,
	linux-doc@...r.kernel.org
Subject: [patch 2/2] mm, selftests: test return value of munmap for MAP_HUGETLB
 memory

When MAP_HUGETLB memory is unmapped, the length must be hugepage aligned,
otherwise it fails with -EINVAL.

All tests currently behave correctly, but it's better to explcitly test
the return value for completeness and document the requirement,
especially if users copy map_hugetlb.c as a sample implementation.

Signed-off-by: David Rientjes <rientjes@...gle.com>
---
 tools/testing/selftests/powerpc/mm/hugetlb_vs_thp_test.c | 8 ++++++--
 tools/testing/selftests/vm/hugetlbfstest.c               | 4 +++-
 tools/testing/selftests/vm/map_hugetlb.c                 | 6 +++++-
 3 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/tools/testing/selftests/powerpc/mm/hugetlb_vs_thp_test.c b/tools/testing/selftests/powerpc/mm/hugetlb_vs_thp_test.c
--- a/tools/testing/selftests/powerpc/mm/hugetlb_vs_thp_test.c
+++ b/tools/testing/selftests/powerpc/mm/hugetlb_vs_thp_test.c
@@ -21,9 +21,13 @@ static int test_body(void)
 		 * Typically the mmap will fail because no huge pages are
 		 * allocated on the system. But if there are huge pages
 		 * allocated the mmap will succeed. That's fine too, we just
-		 * munmap here before continuing.
+		 * munmap here before continuing.  munmap() length of
+		 * MAP_HUGETLB memory must be hugepage aligned.
 		 */
-		munmap(addr, SIZE);
+		if (munmap(addr, SIZE)) {
+			perror("munmap");
+			return 1;
+		}
 	}
 
 	p = mmap(addr, SIZE, PROT_READ | PROT_WRITE,
diff --git a/tools/testing/selftests/vm/hugetlbfstest.c b/tools/testing/selftests/vm/hugetlbfstest.c
--- a/tools/testing/selftests/vm/hugetlbfstest.c
+++ b/tools/testing/selftests/vm/hugetlbfstest.c
@@ -34,6 +34,7 @@ static void do_mmap(int fd, int extra_flags, int unmap)
 	int *p;
 	int flags = MAP_PRIVATE | MAP_POPULATE | extra_flags;
 	u64 before, after;
+	int ret;
 
 	before = read_rss();
 	p = mmap(NULL, length, PROT_READ | PROT_WRITE, flags, fd, 0);
@@ -44,7 +45,8 @@ static void do_mmap(int fd, int extra_flags, int unmap)
 			!"rss didn't grow as expected");
 	if (!unmap)
 		return;
-	munmap(p, length);
+	ret = munmap(p, length);
+	assert(!ret || !"munmap returned an unexpected error");
 	after = read_rss();
 	assert(llabs(after - before) < 0x40000 ||
 			!"rss didn't shrink as expected");
diff --git a/tools/testing/selftests/vm/map_hugetlb.c b/tools/testing/selftests/vm/map_hugetlb.c
--- a/tools/testing/selftests/vm/map_hugetlb.c
+++ b/tools/testing/selftests/vm/map_hugetlb.c
@@ -73,7 +73,11 @@ int main(void)
 	write_bytes(addr);
 	ret = read_bytes(addr);
 
-	munmap(addr, LENGTH);
+	/* munmap() length of MAP_HUGETLB memory must be hugepage aligned */
+	if (munmap(addr, LENGTH)) {
+		perror("munmap");
+		exit(1);
+	}
 
 	return ret;
 }
--
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