Re: [PATCH 1/2] drm/amdkfd: Use mmget_not_zero in MMU notifier

[Felix Kuehling]

Am 2022-05-30 um 10:57 schrieb Philip Yang:

MMU notifier callback may pass in mm with mm->mm_users==0 when process
is exiting, use mmget_no_zero to avoid accessing invalid mm in deferred
list work after mm is gone.

Signed-off-by: Philip Yang <philip.y...@amd.com>

Reviewed-by: Felix Kuehling <felix.kuehl...@amd.com>

---
  drivers/gpu/drm/amd/amdkfd/kfd_svm.c | 3 +++
  1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c 
b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
index 835b5187f0b8..2ba3de0fb8aa 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
@@ -2307,6 +2307,8 @@ svm_range_cpu_invalidate_pagetables(struct 
mmu_interval_notifier *mni,

if (range->event == MMU_NOTIFY_RELEASE)

                return true;
+       if (!mmget_not_zero(mni->mm))
+               return true;

start = mni->interval_tree.start;

        last = mni->interval_tree.last;
@@ -2333,6 +2335,7 @@ svm_range_cpu_invalidate_pagetables(struct 
mmu_interval_notifier *mni,
        }

svm_range_unlock(prange);

+       mmput(mni->mm);

return true;

  }