Re: [PATCH i-g-t v3 4/8] tests/intel/xe_madvise: Add dontneed-after-mmap subtest

["Yadav, Arvind" <arvind.yadav@intel.com>]

On 23-02-2026 11:22, Sharma, Nishit wrote:
>
> On 2/23/2026 10:40 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 4/8] tests/intel/xe_madvise: Add 
>>> dontneed-after-
>>> mmap subtest
>>>
>>> This test verifies that an existing mmap becomes invalid after the 
>>> BO is marked
>>> as purgeable and purged. The test creates a BO, maps it, writes 
>>> data, then
>>> marks it DONTNEED and triggers memory pressure.
>>> Accessing the previously valid mapping should now trigger SIGBUS or 
>>> SIGSEGV,
>>> confirming that existing mappings are correctly invalidated when the 
>>> backing
>>> store is purged.
>>>
>>> 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 | 54
>>> ++++++++++++++++++++++++++++++++++++++++
>>>   1 file changed, 54 insertions(+)
>>>
>>> diff --git a/tests/intel/xe_madvise.c b/tests/intel/xe_madvise.c index
>>> 7dbe70f42..5c6a24553 100644
>>> --- a/tests/intel/xe_madvise.c
>>> +++ b/tests/intel/xe_madvise.c
>>> @@ -196,6 +196,54 @@ static void test_dontneed_before_mmap(int fd,
>>> struct drm_xe_engine_class_instanc
>>>       xe_vm_destroy(fd, vm);
>>>   }
>>>
>>> +/**
>>> + * SUBTEST: dontneed-after-mmap
>>> + * Description: Mark BO as DONTNEED after mmap, verify SIGBUS on
>>> +accessing purged mapping
>>> + * Test category: functionality test
>>> + */
>>> +static void test_dontneed_after_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, true);
>>> +
>>> +    map = xe_bo_map(fd, bo, bo_size);
>>> +    memset(map, 0xAB, bo_size);
>>> +
>>> +    if (!purgeable_mark_and_verify_purged(fd, vm, addr, bo_size))
>>> +        igt_skip("Unable to induce purge on this platform/config");
> Same comment as in [Patch- 3/8]


Noted,

>>> +
>>> +    /* Access purged mapping - should trigger SIGBUS/SIGSEGV */
>>> +    {
>>> +        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);
>>> +        if (sig == SIGBUS || sig == SIGSEGV) {
>>> +            /* Expected - purged mapping access failed */
>>> +        } else if (sig == 0) {
>>> +            *ptr = 0;
>>> +            igt_assert_f(false, "Access to purged mapping should
>>> trigger signal\n");
>>> +        } else {
>>> +            igt_assert_f(false, "unexpected signal %d\n", sig);
>>> +        }
> same comment as in [Patch-3/8]


Noted,

Thanks,
Arvind

>>> +
>>> +        signal(SIGBUS, old_sigbus);
>>> +        signal(SIGSEGV, old_sigsegv);
>>> +    }
>>> +
>>> +    munmap(map, bo_size);
>>> +    gem_close(fd, bo);
>>> +    xe_vm_destroy(fd, vm);
>>> +}
>>> +
>> Reviewed-by: Pravalika Gurram <pravalika.gurram@intel.com>
>>>   int igt_main()
>>>   {
>>>       struct drm_xe_engine_class_instance *hwe; @@ -212,6 +260,12 @@
>>> int igt_main()
>>>               break;
>>>           }
>>>
>>> +    igt_subtest("dontneed-after-mmap")
>>> +        xe_for_each_engine(fd, hwe) {
>>> +            test_dontneed_after_mmap(fd, hwe);
>>> +            break;
>>> +        }
>>> +
>>>       igt_fixture() {
>>>           xe_device_put(fd);
>>>           drm_close_driver(fd);
>>> -- 
>>> 2.43.0