Re: [PATCH i-g-t v3 3/8] tests/intel/xe_madvise: Add dontneed-before-mmap subtest

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

[-- Attachment #1: Type: text/plain, Size: 8777 bytes --]


On 2/23/2026 10:39 AM, Gurram, Pravalika wrote:
>
>> -----Original Message-----
>> From: Yadav, Arvind<arvind.yadav@intel.com>
>> Sent: Tuesday, 17 February, 2026 08:04 AM
>> To:igt-dev@lists.freedesktop.org
>> Cc: Brost, Matthew<matthew.brost@intel.com>; Ghimiray, Himal Prasad
>> <himal.prasad.ghimiray@intel.com>;thomas.hellstrom@linux.intel.com;
>> Sharma, Nishit<nishit.sharma@intel.com>; Gurram, Pravalika
>> <pravalika.gurram@intel.com>
>> Subject: [PATCH i-g-t v3 3/8] tests/intel/xe_madvise: Add dontneed-before-
>> mmap subtest
>>
>> This test validates kernel behavior when mapping a BO that was already
>> marked as purgeable and purged before mmap. After purging the BO under
>> memory pressure, the test attempts to mmap and access it. The kernel should
>> trigger SIGBUS or SIGSEGV when accessing the purged mapping, confirming
>> that purged memory is properly invalidated.
>>
>> Cc: Nishit Sharma<nishit.sharma@intel.com>
>> Cc: Pravalika Gurram<pravalika.gurram@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>
>> Signed-off-by: Arvind Yadav<arvind.yadav@intel.com>
>> ---
>>   tests/intel/xe_madvise.c | 219
>> +++++++++++++++++++++++++++++++++++++++
>>   tests/meson.build        |   1 +
>>   2 files changed, 220 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..7dbe70f42
>> --- /dev/null
>> +++ b/tests/intel/xe_madvise.c
>> @@ -0,0 +1,219 @@
>> +// 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"
>> +
>> +/* Purgeable test constants */
>> +#define PURGEABLE_ADDR		0x1a0000
>> +#define PURGEABLE_BO_SIZE	4096
>> +
>> +/**
>> + * trigger_memory_pressure - Fill VRAM + 25% to force purgeable reclaim
>> + * @fd: DRM file descriptor
>> + * @vm: VM handle (unused, kept for API compatibility)
>> + *
>> + * Allocates BOs in a temporary VM until VRAM is overcommitted,
>> + * forcing the kernel to purge DONTNEED-marked BOs.
>> + */
>> +static void trigger_memory_pressure(int fd, uint32_t vm) {
>> +	uint64_t vram_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);
>> +	/* Scale overpressure to 25% of VRAM, minimum 64MB */
>> +	overpressure = vram_size / 4;
>> +	if (overpressure < (64 << 20))
>> +		overpressure = 64 << 20;
>> +
>> +	max_objs = (vram_size + overpressure) / chunk + 1;
>> +	handles = malloc(max_objs * sizeof(*handles));
>> +	igt_assert(handles);
>> +
>> +	total = 0;
>> +	while (total < vram_size + overpressure && n < max_objs) {
>> +		handle = xe_bo_create(fd, temp_vm, chunk,
>> +				      vram_if_possible(fd, 0),
>> +
>> DRM_XE_GEM_CREATE_FLAG_NEEDS_VISIBLE_VRAM);
>> +		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 VRAM */
>> +		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);
>> +}
>> +
>> +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;
>> +}
>> +
>> +/**
>> + * 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 or
>> +SIGBUS on access
>> + * Test category: functionality test
>> + */
>> +static void test_dontneed_before_mmap(int fd, struct
>> +drm_xe_engine_class_instance *hwe) {
>> +	uint32_t bo, vm;
>> +	uint64_t addr = PURGEABLE_ADDR;
>> +	size_t bo_size = PURGEABLE_BO_SIZE;
>> +	void *map;
>> +
>> +	purgeable_setup_simple_bo(fd, &vm, &bo, addr, bo_size, false);
>> +	if (!purgeable_mark_and_verify_purged(fd, vm, addr, bo_size))
>> +		igt_skip("Unable to induce purge on this platform/config");
No cleanup before igt_skip() or it's handled somewhere. gem_close(fd, 
bo) and xe_vm_destroy(fd, vm);
>> +
>> +	/* mmap the purged BO - access should trigger SIGBUS */
>> +	map = xe_bo_map(fd, bo, bo_size);
Should check igt_assert(map != MAP_FAILED) before using it below.
>> +
>> +	{
>> +		sighandler_t old_sigsegv, old_sigbus;
>> +		char *ptr = (char *)map;
>> +		int sig;
>> +
>> +		old_sigsegv = signal(SIGSEGV, (__sighandler_t)sigtrap);
>> +		old_sigbus = signal(SIGBUS, (__sighandler_t)sigtrap);
>> +
>> +		sig = sigsetjmp(jmp, SIGBUS | SIGSEGV);
>> +		switch (sig) {
>> +		case SIGBUS:
>> +		case SIGSEGV:
>> +			/* Expected - purged BO access failed */
>> +			break;
>> +		case 0:
>> +			*ptr = 0;
>> +			__attribute__ ((fallthrough));

why this __attribute__? Any compiler warning? Can't it be handled like

case 0:

default:

     *ptr = 0;

igt_assert_f(false, "Access to purged mmap should trigger SIGBUS, got 
sig=%d\n", sig);

break;

as you are doing intentional fallout from case 0 to default?

>> +		default:
>> +			igt_assert_f(false,
>> +				     "Access to purged mmap should trigger
>> SIGBUS, got sig=%d\n",
>> +				     sig);
>> +			break;
>> +		}
>> +
>> +		signal(SIGBUS, old_sigbus);
>> +		signal(SIGSEGV, old_sigsegv);
>> +		munmap(map, bo_size);
>> +	}
>> +
>> +	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_subtest("dontneed-before-mmap")
>> +		xe_for_each_engine(fd, hwe) {
>> +			test_dontneed_before_mmap(fd, hwe);
>> +			break;
>> +		}
>> +
>> +	igt_fixture() {
>> +		xe_device_put(fd);
>> +		drm_close_driver(fd);
>> +	}
>> +}
> Reviewed-by: Pravalika Gurram<pravalika.gurram@intel.com>
>> diff --git a/tests/meson.build b/tests/meson.build index
>> 0ad728b87..9d41d7de6 100644
>> --- a/tests/meson.build
>> +++ b/tests/meson.build
>> @@ -313,6 +313,7 @@ intel_xe_progs = [
>>   	'xe_huc_copy',
>>   	'xe_intel_bb',
>>   	'xe_live_ktest',
>> +	'xe_madvise',
>>   	'xe_media_fill',
>>   	'xe_mmap',
>>           'xe_module_load',
>> --
>> 2.43.0

[-- Attachment #2: Type: text/html, Size: 11063 bytes --]