[PATCH 1/2] selftests/mm: compaction_test: Fix incorrect write of zero to nr_hugepages

[Dev Jain <dev.jain@arm.com>]

nr_hugepages is not set to zero because the file offset has not been reset
after read(). Fix that using lseek().

Fixes: bd67d5c15cc1 ("Test compaction of mlocked memory")
Cc: stable@vger.kernel.org 
Signed-off-by: Dev Jain <dev.jain@arm.com>
---
Merge dependency: https://lore.kernel.org/all/20240513082842.4117782-1-dev.jain@arm.com/
Andrew, does it sound reasonable to have the fixes tag in the above
patch too, along with this series?

 tools/testing/selftests/mm/compaction_test.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/tools/testing/selftests/mm/compaction_test.c b/tools/testing/selftests/mm/compaction_test.c
index 533999b6c284..c5be395f8363 100644
--- a/tools/testing/selftests/mm/compaction_test.c
+++ b/tools/testing/selftests/mm/compaction_test.c
@@ -107,6 +107,8 @@ int check_compaction(unsigned long mem_free, unsigned int hugepage_size)
 		goto close_fd;
 	}
 
+	lseek(fd, 0, SEEK_SET);
+
 	/* Start with the initial condition of 0 huge pages*/
 	if (write(fd, "0", sizeof(char)) != sizeof(char)) {
 		ksft_print_msg("Failed to write 0 to /proc/sys/vm/nr_hugepages: %s\n",
-- 
2.30.2