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

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

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]
>> +
>> +	/* 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]
>> +
>> +		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