Re: [PATCH i-g-t 1/1] tests/intel/xe_evict: overcommit tests for fault-mode and non-fault-mode VMs

["Sharma, Nishit" <nishit.sharma@intel.com>]

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On 1/13/2026 12:38 PM, Sobin Thomas wrote:
> 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);
fd already passed from calling function. So no need to call 
drm_open_driver() again
> +	phys_mem = (uint64_t)igt_get_total_ram_mb() << 20;
system_size defined in igt_fixture() which can be passed as argument in 
test_vm_nonfault_mode_overcommit() and can be used.
> +	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));
is it expected to get error code apart from E2BIG, ENOMEM and ENOSPC 
which is being printed in igt_info? If it's not then igt_info can be 
removed as error code printing and test halt done in igt_assert().
> +		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);
We can use 6th argument which is offset as 0 so that it can take address 
to bind overcommit_size automatically
> +	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);
Same as above. physical memory size defined in igt_fixture() which can 
be passed as argument in test_vm_fault_mode_overcommit()
> +	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);
fd already passed in function so why drm_reopen_driver()?
> +
> +	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));
why not igt_assert() if bo_create() failed with error?
> +		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));
Can't we assert here?
> +		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);
This should be for (off = 0; off < overcommit_size; off += 4096) as page 
alignment above set is 4096 and we are checking whether pages in 
overcommit_size is accessible
> +	     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

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