[i-g-t] tests/intel/xe_madvise: Skip purge tests under low RAM

[Arvind Yadav <arvind.yadav@intel.com>]

The purge tests create memory pressure to trigger BO eviction. If the
system is already low on RAM, this extra pressure can push the machine
into OOM and kill the test before it can clean up.

Check available RAM before starting the pressure allocation and skip when
there is not enough memory.

Cc: Pravalika Gurram <pravalika.gurram@intel.com>
Cc: Nishit Sharma <nishit.sharma@intel.com>
Signed-off-by: Arvind Yadav <arvind.yadav@intel.com>
---
 tests/intel/xe_madvise.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/tests/intel/xe_madvise.c b/tests/intel/xe_madvise.c
index cdb115d7e..f9e2c4735 100644
--- a/tests/intel/xe_madvise.c
+++ b/tests/intel/xe_madvise.c
@@ -83,7 +83,7 @@ static void purgeable_setup_simple_bo(int fd, uint32_t *vm, uint32_t *bo,
 static void trigger_memory_pressure(int fd)
 {
 	uint64_t mem_size, overpressure;
-	const uint64_t chunk = 8ull << 20; /* 8 MiB */
+	const uint64_t chunk = 8ULL << 20; /* 8 MiB */
 	int max_objs, n = 0;
 	uint32_t *handles;
 	uint64_t total;
@@ -98,14 +98,18 @@ static void trigger_memory_pressure(int fd)
 
 	/* dGPU: fill VRAM + 50 % to force TTM eviction */
 	mem_size = xe_visible_vram_size(fd, 0);
-	overpressure = mem_size / 2;
-	if (overpressure < (64 << 20))
-		overpressure = 64 << 20;
+	overpressure = max_t(uint64_t, mem_size / 2, 64ULL << 20);
+	max_objs = DIV_ROUND_UP(mem_size + overpressure, chunk);
+
+	/*
+	 * Pressure BOs are faulted in and kept alive until cleanup. If the
+	 * system is already low on RAM, this can cause OOM.
+	 */
+	igt_require_memory(max_objs, chunk, CHECK_RAM);
 
 	/* Separate VM so pressure BOs don't interfere with the test */
 	vm = xe_vm_create(fd, 0, 0);
 
-	max_objs = (mem_size + overpressure) / chunk + 1;
 	handles = malloc(max_objs * sizeof(*handles));
 	igt_assert(handles);
 
-- 
2.43.0