Re: [PATCH i-g-t v7 5/9] tests/intel/xe_madvise: Add dontneed-after-mmap subtest

Sharma, Nishit
2026-04-10T08:23:04Z

On 4/9/2026 12:31 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.
>
> v7:
> - Move sigtrap/jmp_buf in this patch. (Nishit)
>
> 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 | 71 ++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 71 insertions(+)
>
> diff --git a/tests/intel/xe_madvise.c b/tests/intel/xe_madvise.c
> index 619d64b46..2d5acc347 100644
> --- a/tests/intel/xe_madvise.c
> +++ b/tests/intel/xe_madvise.c
> @@ -153,6 +153,13 @@ static bool purgeable_mark_and_verify_purged(int fd, uint32_t vm, uint64_t addr,
> return retained == 0;
> }
>
> +static jmp_buf jmp;
> +
> +__noreturn static void sigtrap(int sig)
> +{
> + siglongjmp(jmp, sig);
> +}
> +
> /**
> * SUBTEST: purged-mmap-blocked
> * Description: After BO is purged, verify mmap() fails with -EINVAL
> @@ -227,6 +234,64 @@ 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)) {
> + munmap(map, bo_size);
> + gem_close(fd, bo);
> + xe_vm_destroy(fd, vm);
> + igt_skip("Unable to induce purge on this platform/config");
Same Nit as in Patch-4/9.
> + }
> +
> + /* 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;

Here if suppose SIGBUS/SIGSEGV is not hit but mapping is invalidated,
here you'll get segfault. Remove *ptr = 0 and club case 0: and default and

let it assert as available

> + 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;
> @@ -251,6 +316,12 @@ 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);

With above changes LGTM:

Reviewed-by: Nishit Sharma <nishit.sharma@intel.com>