The existing tests in xe_evict focuses on system-wide memory allocation
across multiple processes. However, OOM error handling in different VM
modes was not being tested, and the previous test_svm_overcommit() had
a critical bug that prevented proper overcommit scenarios.

Add three new tests to verify graceful OOM failure handling:

- test_evict_oom(): Allocates BOs aggressively in a loop until
  OOM occurs. Tests error handling in LR mode and expects
  -ENOSPC or -ENOMEM.

- test_vm_nonfault_mode_overcommit(): Verifies that non-fault mode VMs
  properly reject overcommit attempts with -ENOSPC or -ENOMEM as
  expected.

- test_vm_fault_mode_overcommit(): Validates that fault-mode VMs can
  handle memory pressure gracefully by touching pages to trigger page
  faults.

Signed-off-by: Sobin Thomas <sobin.thomas@intel.com>
---
 tests/intel/xe_evict.c | 330 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 330 insertions(+)

diff --git a/tests/intel/xe_evict.c b/tests/intel/xe_evict.c
index 2350487c8..0f739ec7b 100644
--- a/tests/intel/xe_evict.c
+++ b/tests/intel/xe_evict.c
@@ -210,6 +210,274 @@ test_evict(int fd, struct drm_xe_engine_class_instance *eci,
 	drm_close_driver(fd);
 }
 
+static int
+test_evict_oom(int fd, struct drm_xe_engine_class_instance *eci,
+	       int n_exec_queues, int n_execs, size_t bo_size, unsigned long flags)
+{
+	uint32_t vm;
+	uint32_t bind_exec_queues[1] = { 0 };
+	uint64_t addr = 0x100000000;
+	uint64_t available_ram;
+	uint64_t total_alloc_size;
+	int bind_err = 0;
+	uint32_t *bo;
+	int i;
+	const size_t min_map_size = 4096;  /* Add constant with proper type */
+
+#define USER_FENCE_VALUE    0xdeadbeefdeadbeefull
+	struct drm_xe_sync sync[1] = {
+		{ .type = DRM_XE_SYNC_TYPE_USER_FENCE, .flags = DRM_XE_SYNC_FLAG_SIGNAL,
+		  .timeline_value = USER_FENCE_VALUE },
+	};
+
+	/* Check if we have enough system memory to proceed */
+	available_ram = igt_get_avail_ram_mb() << 20;
+	/* Calculate total allocation size - now for full n_execs */
+	total_alloc_size = (uint64_t)n_execs * bo_size;
+
+	if (available_ram < (total_alloc_size / 4)) {
+		igt_info("Insufficient memory to run OOM test safely\n");
+		return -ENOMEM;
+	}
+	if (total_alloc_size > available_ram) {
+		int safe_n_execs = available_ram / bo_size;
+
+		safe_n_execs = ALIGN_DOWN(safe_n_execs, 4);
+		if (safe_n_execs < 4) {
+			igt_info("Not enough memory to run OOM test\n");
+			return -ENOMEM;
+		}
+		igt_info("Reducing n_execs from %d to %d to fit in available memory\n",
+			 n_execs, safe_n_execs);
+		n_execs = safe_n_execs;
+		total_alloc_size = (uint64_t)n_execs * bo_size;
+	}
+	igt_info("OOM test: n_execs=%d, bo_size=%llu MB, total_alloc=%llu MB, available=%llu MB\n",
+		 n_execs, (unsigned long long)(bo_size >> 20),
+		 (unsigned long long)(total_alloc_size >> 20),
+		 (unsigned long long)(available_ram >> 20));
+
+	/* Allocate array for n_execs BOs */
+	bo = calloc(n_execs, sizeof(*bo));
+	igt_assert(bo);
+
+	fd = drm_reopen_driver(fd);
+
+	vm = xe_vm_create(fd, DRM_XE_VM_CREATE_FLAG_LR_MODE, 0);
+	bind_exec_queues[0] = xe_bind_exec_queue_create(fd, vm, 0);
+
+	igt_info("\n n_execs = %d, bo_size = %zu\n", n_execs, bo_size);
+
+	/* Try to allocate and bind more than available memory */
+	for (i = 0; i < n_execs; i++) {
+		uint32_t __bo;
+		struct {
+		uint64_t vm_sync;
+		} *data;
+		int create_ret;
+		size_t map_size;  /* Use size_t for map size */
+
+		/* Use __xe_bo_create to handle allocation failures gracefully */
+		create_ret = __xe_bo_create(fd, 0, bo_size, vram_memory(fd, eci->gt_id),
+					    DRM_XE_GEM_CREATE_FLAG_NEEDS_VISIBLE_VRAM,
+					    NULL, &__bo);
+		if (create_ret) {
+			bind_err = -errno;
+			igt_info("BO create failed at iteration %d with error %d (%s)\n",
+				 i, -bind_err, strerror(-bind_err));
+			break;
+		}
+
+		bo[i] = __bo;
+
+		/* Calculate map size with same types */
+		map_size = sizeof(*data) > min_map_size ? sizeof(*data) : min_map_size;
+		data = xe_bo_map(fd, __bo, map_size);
+		sync[0].addr = to_user_pointer(&data->vm_sync);
+		bind_err = __xe_vm_bind(fd, vm, bind_exec_queues[0], __bo, 0, addr,
+					bo_size, DRM_XE_VM_BIND_OP_MAP, 0, sync,
+					1, 0, 0, 0);
+		/* Attempt bind - should eventually fail with -ENOSPC or -ENOMEM */
+		if (bind_err) {
+			bind_err = -errno;
+			igt_info("Bind failed at iteration %d with error %d (%s)\n",
+				 i, -bind_err, strerror(-bind_err));
+			munmap(data, map_size);
+			gem_close(fd, __bo);
+			bo[i] = 0;
+			break;
+		}
+
+		xe_wait_ufence(fd, &data->vm_sync, USER_FENCE_VALUE,
+			       bind_exec_queues[0], 20 * NSEC_PER_SEC);
+
+		/* Unmap with the same size we used for mapping */
+		munmap(data, map_size);
+		addr += bo_size;
+	}
+
+	/* Cleanup allocated BOs - iterate through all n_execs */
+	for (int j = 0; j < n_execs; j++) {
+		if (bo[j])
+			gem_close(fd, bo[j]);
+	}
+
+	xe_exec_queue_destroy(fd, bind_exec_queues[0]);
+	xe_vm_destroy(fd, vm);
+	drm_close_driver(fd);
+	free(bo);
+
+	return bind_err;
+}
+
+static unsigned int oom_working_set(uint64_t vram_size, uint64_t system_size,
+				    uint64_t bo_size)
+{
+	uint64_t target_allocation;
+	unsigned int set_size;
+
+	/*
+	 * For VRAM eviction testing, we want to allocate MORE than VRAM size
+	 * to force eviction to system memory. Target 150-200% of VRAM.
+	 * The BOs are created with VRAM placement, so they'll initially go to VRAM
+	 * and then get evicted to system when VRAM fills up.
+	 */
+	target_allocation = (vram_size * 150) / 100;  /* 150% of VRAM */
+
+	/* But ensure we don't exceed available system memory */
+	if (target_allocation > (system_size * 80) / 100) {
+		target_allocation = (system_size * 80) / 100;
+		igt_info("Limited by system memory: reducing target from %llu MB to %llu MB\n",
+			 (unsigned long long)((vram_size * 150 / 100) >> 20),
+			 (unsigned long long)(target_allocation >> 20));
+	}
+
+	set_size = target_allocation / bo_size;
+
+	igt_info("VRAM stress calculation: vram_size=%" PRIu64 " MB, system=%" PRIu64 " MB, "
+		 "target_alloc=%" PRIu64 " MB (%.1f%% of VRAM), bo_size=%" PRIu64 " MB, set_size=%u\n",
+		 (uint64_t)(vram_size >> 20), (uint64_t)(system_size >> 20),
+		 (uint64_t)(target_allocation >> 20),
+		 (double)(target_allocation * 100) / vram_size,
+		 (uint64_t)(bo_size >> 20), set_size);
+
+	return ALIGN_DOWN(set_size, 4);
+}
+
+static void
+test_vm_nonfault_mode_overcommit(int fd, struct drm_xe_engine_class_instance *eci,
+				 uint64_t vram_size, uint64_t overcommit_multiplier)
+{
+	uint32_t bo;
+	uint64_t phys_mem;
+	uint64_t overcommit_size;
+	uint32_t vm;
+	int ret, cret;
+
+	fd = drm_open_driver(DRIVER_XE);

+	phys_mem = (uint64_t)igt_get_total_ram_mb() << 20;

+	igt_info("Total system memory = %llu MB\n", (unsigned long long)phys_mem);
+	overcommit_size = ALIGN(phys_mem * 2, 4096);
+	vm = xe_vm_create(fd, 0, 0);
+	cret = __xe_bo_create(fd, vm, overcommit_size,
+			      vram_memory(fd, eci->gt_id) | system_memory(fd),
+			      0, NULL, &bo);
+	if (cret) {
+		igt_assert_f(errno == E2BIG || errno == ENOMEM || errno == ENOSPC,
+			     "xe_bo_create failed with unexpected errno=%d (%s)\n",
+			     errno, strerror(errno));
+		igt_info("Non-fault overcommit: BO create failed as expected: %d (%s)\n",
+			 errno, strerror(errno));

+		xe_vm_destroy(fd, vm);
+		drm_close_driver(fd);
+		return;
+	}
+
+	ret = __xe_vm_bind(fd, vm, 0, bo, 0, 0x100000000,
+			   overcommit_size, DRM_XE_VM_BIND_OP_MAP, 0,
+			   NULL, 0, 0, 0, 0);

+	igt_assert_f(ret == -ENOMEM || ret == -ENOSPC,
+		     "Expected bind to fail with -ENOMEM/-ENOSPC, got %d\n", ret);
+
+	gem_close(fd, bo);
+	xe_vm_destroy(fd, vm);
+	drm_close_driver(fd);
+}
+
+static void test_vm_fault_mode_overcommit(int fd, struct drm_xe_engine_class_instance *eci,
+					  uint64_t vram_size, uint64_t overcommit_multiplier)
+{
+	uint64_t phys_mem = igt_get_total_ram_mb() << 20;
+	uint64_t available_mem = igt_get_avail_ram_mb() << 20;
+	uint64_t overcommit_size;
+	uint32_t vm;
+	uint32_t bo;
+	uint64_t *ptr;
+	int create_ret;
+
+	/* Limit overcommit to available memory to avoid OOM killer */
+	overcommit_size = ALIGN(phys_mem * overcommit_multiplier, 4096);

+	if (overcommit_size > available_mem) {
+		igt_info("Limiting overcommit size from %llu MB to %llu MB (available)\n",
+			 (unsigned long long)(overcommit_size >> 20),
+			 (unsigned long long)(available_mem >> 20));
+		overcommit_size = ALIGN(available_mem, 4096);
+	}
+
+	/* Need at least some reasonable size to test */
+	if (overcommit_size < (vram_size * 2)) {
+		igt_skip("Insufficient memory for fault mode overcommit test\n");
+		return;
+	}
+
+	igt_info("Fault mode overcommit test: size=%llu MB, vram=%llu MB\n",
+		 (unsigned long long)(overcommit_size >> 20),
+		 (unsigned long long)(vram_size >> 20));
+
+	fd = drm_reopen_driver(fd);

+
+	vm = xe_vm_create(fd, DRM_XE_VM_CREATE_FLAG_LR_MODE |
+			  DRM_XE_VM_CREATE_FLAG_FAULT_MODE, 0);
+	igt_assert(vm);
+
+	create_ret = __xe_bo_create(fd, 0, overcommit_size,
+				    vram_memory(fd, eci->gt_id) | system_memory(fd),
+				    DRM_XE_GEM_CREATE_FLAG_NEEDS_VISIBLE_VRAM,
+				    NULL, &bo);
+	if (create_ret) {
+		igt_info("BO creation failed (expected for overcommit): %s\n",
+			 strerror(-create_ret));

+		xe_vm_destroy(fd, vm);
+		drm_close_driver(fd);
+		return;
+	}
+
+	ptr = xe_bo_map(fd, bo, overcommit_size);
+	if (ptr == MAP_FAILED) {
+		igt_info("BO mapping failed (expected for overcommit): %s\n",
+			 strerror(errno));

+		gem_close(fd, bo);
+		xe_vm_destroy(fd, vm);
+		drm_close_driver(fd);
+		return;
+	}
+
+	/* Touch first page */
+	memset(ptr, 0xAA, 4096);
+
+	/* Touch sparse pages to test fault handling - limit to avoid OOM */
+	for (uint64_t off = 0; off < overcommit_size && off < (available_mem / 2);

+	     off += (4096 * 256))
+		((char *)ptr)[off] = 0xBB;
+
+	igt_info("Fault mode overcommit test completed successfully\n");
+
+	munmap(ptr, overcommit_size);
+	gem_close(fd, bo);
+	xe_vm_destroy(fd, vm);
+	drm_close_driver(fd);
+}
+
 static void
 test_evict_cm(int fd, struct drm_xe_engine_class_instance *eci,
 	      int n_exec_queues, int n_execs, size_t bo_size, unsigned long flags,
@@ -665,7 +933,29 @@ static unsigned int working_set(uint64_t vram_size, uint64_t system_size,
  * @beng-threads-large:		bind exec_queue threads large
  *
  */
+/**
+ * SUBTEST: evict-vm-nonfault-overcommit
+ * Description: VM non-fault mode overcommit test - expects bind failure
+ * Test category: functionality test
+ * Feature: VM bind
+ */
 
+/**
+ * SUBTEST: evict-vm-fault-overcommit
+ * Description: VM fault mode overcommit test - touch pages to trigger faults
+ * Test category: functionality test
+ * Feature: VM bind, fault mode
+ */
+/**
+ * SUBTEST: evict-%s
+ * Description: %arg[1] out-of-memory evict test - expects graceful failure
+ * Test category: functionality test
+ *
+ * arg[1]:
+ *
+ * @oom-graceful:       OOM graceful failure with small BOs
+ * @oom-graceful-large: OOM graceful failure with large BOs
+ */
 /*
  * Table driven test that attempts to cover all possible scenarios of eviction
  * (small / large objects, compute mode vs non-compute VMs, external BO or BOs
@@ -730,6 +1020,17 @@ int igt_main()
 			MULTI_VM },
 		{ NULL },
 	};
+	const struct section_oom {
+		const char *name;
+		int n_exec_queues;
+		int mul;
+		int div;
+		unsigned int flags;
+} sections_oom[] = {
+	{ "oom-graceful", 1, 1, 128, BIND_EXEC_QUEUE },
+	{ "oom-graceful-large", 1, 1, 16, BIND_EXEC_QUEUE },
+	{ NULL },
+};
 	const struct section_threads {
 		const char *name;
 		int n_threads;
@@ -836,6 +1137,14 @@ int igt_main()
 		}
 	}
 
+	igt_subtest("evict-vm-nonfault-overcommit") {
+		test_vm_nonfault_mode_overcommit(fd, hwe, vram_size, 2);
+	}
+
+	igt_subtest("evict-vm-fault-overcommit") {
+		test_vm_fault_mode_overcommit(fd, hwe, vram_size, 2);
+	}
+
 	for (const struct section_cm *s = sections_cm; s->name; s++) {
 		igt_subtest_f("evict-%s", s->name) {
 			uint64_t bo_size = calc_bo_size(vram_size, s->mul, s->div);
@@ -862,6 +1171,27 @@ int igt_main()
 				min(ws, s->n_execs), bo_size, s->flags);
 		}
 	}
+	for (const struct section_oom *s = sections_oom; s->name; s++) {
+		igt_subtest_f("evict-%s", s->name) {
+			uint64_t bo_size = calc_bo_size(vram_size, s->mul, s->div);
+			int n_execs = oom_working_set(vram_size, system_size, bo_size);
+			int ret;
+
+			igt_info("OOM test: n_execs %d, bo_size %" PRIu64 " MiB\n",
+				 n_execs, bo_size >> 20);
+
+			ret = test_evict_oom(fd, hwe, s->n_exec_queues, n_execs,
+					     bo_size, s->flags);
+
+			/* Accept success or graceful OOM errors */
+			igt_assert(ret == 0 || ret == -ENOSPC || ret == -ENOMEM);
+			if (ret != 0)
+				igt_info("Test passed: Got expected error %d (%s)\n",
+					 ret, strerror(-ret));
+			else
+				igt_info("Test passed: All allocations and binds succeeded\n");
+	}
+}
 
 	igt_fixture()
 		drm_close_driver(fd);

Let @Hellstrom, Thomas have a look on this. 

Regards

Nishit