Re: [PATCH] drm/i915/selftests: exercise shmem_writeback with THP

On 21/09/2021 15:21, Matthew Auld wrote:

In commit:

commit 1e6decf30af5c5c75445ed6ad4e65a26de578a03 Author: Hugh Dickins hughd@google.com Date: Thu Sep 2 14:54:43 2021 -0700

 shmem: shmem_writepage() split unlikely i915 THP

it looks THP + shmem_writeback was an unexpected combination, and ends up hitting some BUG_ON, but it also looks like that is now fixed.

While the IGTs did eventually hit this(although not during pre-merge it seems), it's likely worthwhile adding some explicit coverage for this scenario in the shrink_thp selftest.

References: https://gitlab.freedesktop.org/drm/intel/-/issues/4166 Signed-off-by: Matthew Auld matthew.auld@intel.com Cc: Tvrtko Ursulin tvrtko.ursulin@linux.intel.com

---

drivers/gpu/drm/i915/gem/selftests/huge_pages.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/gem/selftests/huge_pages.c b/drivers/gpu/drm/i915/gem/selftests/huge_pages.c index 0827634c842c..8260a533d43f 100644 --- a/drivers/gpu/drm/i915/gem/selftests/huge_pages.c +++ b/drivers/gpu/drm/i915/gem/selftests/huge_pages.c @@ -1589,7 +1589,8 @@ static int igt_shrink_thp(void *arg) i915_gem_shrink(NULL, i915, -1UL, NULL, I915_SHRINK_BOUND | I915_SHRINK_UNBOUND |

• 	I915_SHRINK_ACTIVE);
  

• 	I915_SHRINK_ACTIVE |
  

• 	I915_SHRINK_WRITEBACK);
  

  if (should_swap == i915_gem_object_has_pages(obj)) { pr_err("unexpected pages mismatch, should_swap=%s\n", yesno(should_swap));

Good idea I think.

Reviewed-by: Tvrtko Ursulin tvrtko.ursulin@intel.com

Regards,

Tvrtko