[PATCH 5.15 008/106] drm/amdkfd: Use mmget_not_zero in MMU notifier

Greg Kroah-Hartman
2022-06-20T13:22:35Z

From: Philip Yang <Philip.Yang@amd.com>

[ Upstream commit fa582c6f3684ac0098a9d02ddf0ed52a02b37127 ]

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.Yang@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 830809b694dd..74e6f613be02 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
@@ -2181,6 +2181,8 @@ 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;
@@ -2207,6 +2209,7 @@ svm_range_cpu_invalidate_pagetables(struct mmu_interval_notifier *mni,
}

svm_range_unlock(prange);
+ mmput(mni->mm);

return true;
}
--
2.35.1