Re: [PATCH i-g-t v6 5/9] tests/intel/xe_madvise: Add dontneed-after-mmap subtest

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

On 3/25/2026 6:14 PM, Arvind Yadav wrote:
> 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.
>
> v4:
>    - Added proper resource cleanup before calling igt_skip(). (Nishit)
>    - Added assertion for xe_bo_map. (Nishit)
>
> v6:
>    - Fix sigsetjmp(jmp, SIGBUS | SIGSEGV) to sigsetjmp(jmp, 1). The
>      second argument is a plain boolean savemask, not a signal set.
>
> 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 | 64 ++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 64 insertions(+)
>
> diff --git a/tests/intel/xe_madvise.c b/tests/intel/xe_madvise.c
> index 81e05b6d4..9a157de1d 100644
> --- a/tests/intel/xe_madvise.c
> +++ b/tests/intel/xe_madvise.c
> @@ -244,6 +244,64 @@ static void test_dontneed_before_mmap(int fd)
>   	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)
> +{
> +	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);
> +	igt_assert(map != MAP_FAILED);
> +	memset(map, 0xAB, bo_size);
> +
> +	if (!purgeable_mark_and_verify_purged(fd, vm, addr, bo_size)) {
same comment as in Patch-4/9
> +		munmap(map, bo_size);
> +		gem_close(fd, bo);
> +		xe_vm_destroy(fd, vm);
> +		igt_skip("Unable to induce purge on this platform/config");
> +	}
> +
> +	/* 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, 1); /* savemask=1: save/restore signal mask */
> +		switch (sig) {
> +		case SIGBUS:
> +		case SIGSEGV:
> +			/* Expected - purged mapping access failed */
> +			break;
> +		case 0:
> +			*ptr = 0;
> +		default:
> +			igt_assert_f(false,
> +				     "Access to purged mapping 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;
> @@ -268,6 +326,12 @@ int igt_main()
>   			break;
>   		}
>   
> +	igt_subtest("dontneed-after-mmap")
> +		xe_for_each_engine(fd, hwe) {
> +			test_dontneed_after_mmap(fd);
> +			break;
> +		}
> +
>   	igt_fixture() {
>   		xe_device_put(fd);
>   		drm_close_driver(fd);