From: Philip Yang <Philip.Yang@amd.com>
Date: Thu, 26 May 2022 20:15:38 +0000 (-0400)
Subject: drm/amdkfd: Use mmget_not_zero in MMU notifier
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=09c5cdbc62d99fc6306a21b24b60eb11a3bd0963;p=linux.git

drm/amdkfd: Use mmget_not_zero in MMU notifier

[ 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>
---

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
index 830809b694dd9..74e6f613be020 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;
 }