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

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

On 4/6/2026 3:23 PM, Sharma, Nishit wrote:
>
> 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.
Correction here, this function is called from subtest 
test_purged_mmap_blocked(fd); which is in Patch-4/9. Please move these 
functions 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',