diff mbox series

[1/3] selftests/mm: virtual_address_range: Fix error when CommitLimit < 1GiB

Message ID 20250107-virtual_address_range-tests-v1-1-3834a2fb47fe@linutronix.de
State New
Headers show
Series selftests/mm: virtual_address_range: Two bugfixes and a cleanup | expand

Commit Message

Thomas Weißschuh Jan. 7, 2025, 3:14 p.m. UTC
If not enough physical memory is available the kernel may fail mmap();
see __vm_enough_memory() and vm_commit_limit().
In that case the logic in validate_complete_va_space() does not make
sense and will even incorrectly fail.
Instead skip the test if no mmap() succeeded.

Fixes: 010409649885 ("selftests/mm: confirm VA exhaustion without reliance on correctness of mmap()")
Cc: stable@vger.kernel.org
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>

---
The logic in __vm_enough_memory() seems weird.
It describes itself as "Check that a process has enough memory to
allocate a new virtual mapping", however it never checks the current
memory usage of the process.
So it only disallows large mappings. But many small mappings taking the
same amount of memory are allowed; and then even automatically merged
into one big mapping.
---
 tools/testing/selftests/mm/virtual_address_range.c | 6 ++++++
 1 file changed, 6 insertions(+)
diff mbox series

Patch

diff --git a/tools/testing/selftests/mm/virtual_address_range.c b/tools/testing/selftests/mm/virtual_address_range.c
index 2a2b69e91950a37999f606847c9c8328d79890c2..d7bf8094d8bcd4bc96e2db4dc3fcb41968def859 100644
--- a/tools/testing/selftests/mm/virtual_address_range.c
+++ b/tools/testing/selftests/mm/virtual_address_range.c
@@ -178,6 +178,12 @@  int main(int argc, char *argv[])
 		validate_addr(ptr[i], 0);
 	}
 	lchunks = i;
+
+	if (!lchunks) {
+		ksft_test_result_skip("Not enough memory for a single chunk\n");
+		ksft_finished();
+	}
+
 	hptr = (char **) calloc(NR_CHUNKS_HIGH, sizeof(char *));
 	if (hptr == NULL) {
 		ksft_test_result_skip("Memory constraint not fulfilled\n");