Re: [PATCH i-g-t v6 3/9] tests/intel/xe_madvise: Add dontneed-before-mmap subtest

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

On 3/25/2026 6:14 PM, Arvind Yadav wrote:
> This test validates that mmap() fails with -EBUSY when attempting to
> map a BO marked DONTNEED. The mmap offset ioctl succeeds (it just
> returns the pre-allocated offset); the purgeable check happens in
> xe_gem_object_mmap() at mmap() time.
>
>    - DONTNEED BOs: return -EBUSY (temporary purgeable state, BO still
>      has backing store but can be purged at any time)
>    - Purged BOs: return -EINVAL (permanent, backing store discarded)
>
> v4:
>    - Move unmap outside the block. (Pravalika)
>    - Added proper resource cleanup before calling igt_skip(). (Nishit)
>    - Added assertion for xe_bo_map. (Nishit)
>
> v5:
>    - Add kernel capability check *_FLAG_HAS_PURGING_SUPPORT for
>      purgeable support. (Jose)
>    - Drop memory pressure trigger path; mark DONTNEED directly and
>      assert -EBUSY from mmap offset ioctl; restore WILLNEED before
>      cleanup.
>
> v6:
>    - Support iGPU by using total system RAM as the pressure baseline
>      instead of VRAM size (which is 0 on iGPU).
>    - Raise overpressure from 25% to 50% of the baseline to ensure the
>      kernel shrinker is forced to reclaim on systems with large free RAM.
>    - The DONTNEED enforcement point is mmap() itself, not the
>      DRM_IOCTL_XE_GEM_MMAP_OFFSET ioctl. Update the test to mark DONTNEED
>      first, then verify DRM_IOCTL_XE_GEM_MMAP_OFFSET still succeeds, and
>      finally verify that mmap() fails with -EBUSY
>
> Cc: Nishit Sharma <nishit.sharma@intel.com>
> Cc: Matthew Brost <matthew.brost@intel.com>
> Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
> Cc: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
> Cc: Pravalika Gurram <pravalika.gurram@intel.com>
> Signed-off-by: Arvind Yadav <arvind.yadav@intel.com>
> ---
>   tests/intel/xe_madvise.c | 233 +++++++++++++++++++++++++++++++++++++++
>   tests/meson.build        |   1 +
>   2 files changed, 234 insertions(+)
>   create mode 100644 tests/intel/xe_madvise.c
>
> diff --git a/tests/intel/xe_madvise.c b/tests/intel/xe_madvise.c
> new file mode 100644
> index 000000000..de4a6e34c
> --- /dev/null
> +++ b/tests/intel/xe_madvise.c
> @@ -0,0 +1,233 @@
> +// SPDX-License-Identifier: MIT
> +/*
> + * Copyright © 2025 Intel Corporation
> + */
> +
> +/**
> + * TEST: Validate purgeable BO madvise functionality
> + * Category: Core
> + * Mega feature: General Core features
> + * Sub-category: Memory management tests
> + * Functionality: madvise, purgeable
> + */
> +
> +#include "igt.h"
> +#include "xe_drm.h"
> +
> +#include "xe/xe_ioctl.h"
> +#include "xe/xe_query.h"
> +
> +static bool xe_has_purgeable_support(int fd)
> +{
> +	struct drm_xe_query_config *config = xe_config(fd);
> +
> +	return config->info[DRM_XE_QUERY_CONFIG_FLAGS] &
> +		DRM_XE_QUERY_CONFIG_FLAG_HAS_PURGING_SUPPORT;
> +}
> +
> +/* Purgeable test constants */
> +#define PURGEABLE_ADDR		0x1a0000
> +#define PURGEABLE_BO_SIZE	4096
> +
> +/**
> + * trigger_memory_pressure - Fill VRAM/RAM + 50% to force purgeable reclaim
> + * @fd: DRM file descriptor
> + * @vm: VM handle (unused, kept for API compatibility)
> + *
> + * Allocates BOs in a temporary VM until memory is overcommitted by 50%,
> + * forcing the kernel to purge DONTNEED-marked BOs.
> + */
> +static void trigger_memory_pressure(int fd, uint32_t vm)
> +{
> +	uint64_t vram_size, mem_size, overpressure;
> +	const uint64_t chunk = 8ull << 20; /* 8 MiB */
> +	int max_objs, n = 0;
> +	uint32_t *handles;
> +	uint64_t total;
> +	void *p;
> +	uint32_t handle, temp_vm;
> +
> +	/* Use a separate VM so pressure BOs don't affect the test VM */
> +	temp_vm = xe_vm_create(fd, 0, 0);
> +
> +	vram_size = xe_visible_vram_size(fd, 0);
> +	if (vram_size > 0) {
> +		/* dGPU: pressure VRAM to trigger purgeable reclaim */
> +		mem_size = vram_size;
> +	} else {
> +		/*
> +		 * iGPU: purgeable BOs reside in system memory. Use *total*
> +		 * RAM (not just available) as the baseline so that we always
> +		 * over-commit regardless of how much is already in use.
> +		 */
> +		mem_size = igt_get_total_ram_mb() << 20;
> +	}
> +
> +	/* Scale overpressure to 50% of memory, minimum 64MB */
> +	overpressure = mem_size / 2;
> +	if (overpressure < (64 << 20))
> +		overpressure = 64 << 20;
> +
> +	max_objs = (mem_size + overpressure) / chunk + 1;
> +	handles = malloc(max_objs * sizeof(*handles));
> +	igt_assert(handles);
> +
> +	total = 0;
> +	while (total < mem_size + overpressure && n < max_objs) {
> +		uint32_t err;
> +
> +		err = __xe_bo_create(fd, temp_vm, chunk,
> +				     vram_if_possible(fd, 0),
> +				     DRM_XE_GEM_CREATE_FLAG_NEEDS_VISIBLE_VRAM,
> +				     NULL, &handle);
> +		if (err) /* Out of memory — sufficient pressure achieved */
> +			break;
> +
> +		handles[n++] = handle;
> +		total += chunk;
> +
> +		p = xe_bo_map(fd, handle, chunk);
> +		igt_assert(p != MAP_FAILED);
> +
> +		/* Fault in all pages so they actually consume memory */
> +		memset(p, 0xCD, chunk);
> +		munmap(p, chunk);
> +	}
> +
> +	/* Allow shrinker time to process pressure */
> +	usleep(100000);
> +
> +	for (int i = 0; i < n; i++)
> +		gem_close(fd, handles[i]);
> +
> +	free(handles);
> +
> +	xe_vm_destroy(fd, temp_vm);
> +}
This function is called from below function which is not part of this 
Patch-3/9. This must be removed and introduced in Patch-4/9.
> +
> +static jmp_buf jmp;
> +
> +__noreturn static void sigtrap(int sig)
> +{
> +	siglongjmp(jmp, sig);
> +}
> +
> +/**
> + * purgeable_mark_and_verify_purged - Mark DONTNEED, pressure, check purged
> + * @fd: DRM file descriptor
> + * @vm: VM handle
> + * @addr: Virtual address of the BO
> + * @size: Size of the BO
> + *
> + * Returns true if the BO was purged under memory pressure.
> + */
> +static bool purgeable_mark_and_verify_purged(int fd, uint32_t vm, uint64_t addr, size_t size)
> +{
> +	uint32_t retained;
> +
> +	/* Mark as DONTNEED */
> +	retained = xe_vm_madvise_purgeable(fd, vm, addr, size,
> +					   DRM_XE_VMA_PURGEABLE_STATE_DONTNEED);
> +	if (retained != 1)
> +		return false;
> +
> +	/* Trigger memory pressure */
> +	trigger_memory_pressure(fd, vm);
> +
> +	/* Verify purged */
> +	retained = xe_vm_madvise_purgeable(fd, vm, addr, size,
> +					   DRM_XE_VMA_PURGEABLE_STATE_WILLNEED);
> +	return retained == 0;
> +}
This function is introduced in test_dontneed_after_mmap() in Patch-4/9. 
Remove this and introduced in Patch-4/9.
> +
> +/**
> + * purgeable_setup_simple_bo - Setup VM and bind a single BO
> + * @fd: DRM file descriptor
> + * @vm: Output VM handle
> + * @bo: Output BO handle
> + * @addr: Virtual address to bind at
> + * @size: Size of the BO
> + * @use_scratch: Whether to use scratch page flag
> + *
> + * Helper to create VM, BO, and bind it at the specified address.
> + */
> +static void purgeable_setup_simple_bo(int fd, uint32_t *vm, uint32_t *bo,
> +				      uint64_t addr, size_t size, bool use_scratch)
> +{
> +	struct drm_xe_sync sync = {
> +		.type = DRM_XE_SYNC_TYPE_USER_FENCE,
> +		.flags = DRM_XE_SYNC_FLAG_SIGNAL,
> +		.timeline_value = 1,
> +	};
> +	uint64_t sync_val = 0;
> +
> +	*vm = xe_vm_create(fd, use_scratch ? DRM_XE_VM_CREATE_FLAG_SCRATCH_PAGE : 0, 0);
> +	*bo = xe_bo_create(fd, *vm, size, vram_if_possible(fd, 0),
> +			   DRM_XE_GEM_CREATE_FLAG_NEEDS_VISIBLE_VRAM);
> +
> +	sync.addr = to_user_pointer(&sync_val);
> +	xe_vm_bind_async(fd, *vm, 0, *bo, 0, addr, size, &sync, 1);
> +	xe_wait_ufence(fd, &sync_val, 1, 0, NSEC_PER_SEC);
> +}
> +
> +/**
> + * SUBTEST: dontneed-before-mmap
> + * Description: Mark BO as DONTNEED before mmap, verify mmap() fails with -EBUSY
> + * Test category: functionality test
> + */
> +static void test_dontneed_before_mmap(int fd)
> +{
> +	uint32_t bo, vm;
> +	uint64_t addr = PURGEABLE_ADDR;
> +	size_t bo_size = PURGEABLE_BO_SIZE;
> +	struct drm_xe_gem_mmap_offset mmo = {};
> +	uint32_t retained;
> +	void *ptr;
> +
> +	purgeable_setup_simple_bo(fd, &vm, &bo, addr, bo_size, false);
> +
> +	/* Mark BO as DONTNEED - new mmap operations must be blocked */
> +	retained = xe_vm_madvise_purgeable(fd, vm, addr, bo_size,
> +					   DRM_XE_VMA_PURGEABLE_STATE_DONTNEED);
> +	igt_assert_eq(retained, 1);
> +
> +	/* Ioctl succeeds even for DONTNEED BO; blocking happens at mmap() time. */
> +	mmo.handle = bo;
> +	igt_assert_eq(igt_ioctl(fd, DRM_IOCTL_XE_GEM_MMAP_OFFSET, &mmo), 0);
> +
> +	/* mmap() on a DONTNEED BO must fail with EBUSY. */
> +	ptr = mmap(NULL, bo_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, mmo.offset);
> +	igt_assert_eq_u64((uint64_t)ptr, (uint64_t)MAP_FAILED);
> +	igt_assert_eq(errno, EBUSY);
> +
> +	/* Restore to WILLNEED before cleanup */
> +	xe_vm_madvise_purgeable(fd, vm, addr, bo_size,
> +				DRM_XE_VMA_PURGEABLE_STATE_WILLNEED);
> +
> +	gem_close(fd, bo);
> +	xe_vm_destroy(fd, vm);
> +}
> +
> +int igt_main()
> +{
> +	struct drm_xe_engine_class_instance *hwe;
> +	int fd;
> +
> +	igt_fixture() {
> +		fd = drm_open_driver(DRIVER_XE);
> +		xe_device_get(fd);
> +		igt_require_f(xe_has_purgeable_support(fd),
> +			      "Kernel does not support purgeable buffer objects\n");
> +	}
> +
> +	igt_subtest("dontneed-before-mmap")
> +		xe_for_each_engine(fd, hwe) {
> +			test_dontneed_before_mmap(fd);
> +			break;
> +		}
> +
> +	igt_fixture() {
> +		xe_device_put(fd);
> +		drm_close_driver(fd);
> +	}
> +}
> diff --git a/tests/meson.build b/tests/meson.build
> index cecb4a8ae..a6370b685 100644
> --- a/tests/meson.build
> +++ b/tests/meson.build
> @@ -314,6 +314,7 @@ intel_xe_progs = [
>   	'xe_huc_copy',
>   	'xe_intel_bb',
>   	'xe_live_ktest',
> +	'xe_madvise',
>   	'xe_media_fill',
>   	'xe_mmap',
>           'xe_module_load',