[PATCH 6.8 510/715] drm/xe: Fix ref counting leak on page fault

[Sasha Levin]

From: Matthew Brost <matthew.brost@xxxxxxxxx>

[ Upstream commit f7da398935f7ddabf1a098714593e032c875cd74 ]

If a page fault occurs on VM not in fault a ref can be leaked. Fix this.

Fixes: dd08ebf6c352 ("drm/xe: Introduce a new DRM driver for Intel GPUs")
Signed-off-by: Matthew Brost <matthew.brost@xxxxxxxxx>
Reviewed-by: Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/20240301041036.238471-1-matthew.brost@xxxxxxxxx
(cherry picked from commit 27b5a3f237fe66dbf2288c2b50973aee8a427e41)
Signed-off-by: Lucas De Marchi <lucas.demarchi@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/gpu/drm/xe/xe_gt_pagefault.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_gt_pagefault.c b/drivers/gpu/drm/xe/xe_gt_pagefault.c
index 73f08f1924df2..e2cf1759527c6 100644
--- a/drivers/gpu/drm/xe/xe_gt_pagefault.c
+++ b/drivers/gpu/drm/xe/xe_gt_pagefault.c
@@ -146,10 +146,12 @@ static int handle_pagefault(struct xe_gt *gt, struct pagefault *pf)
 	/* ASID to VM */
 	mutex_lock(&xe->usm.lock);
 	vm = xa_load(&xe->usm.asid_to_vm, pf->asid);
-	if (vm)
+	if (vm && xe_vm_in_fault_mode(vm))
 		xe_vm_get(vm);
+	else
+		vm = NULL;
 	mutex_unlock(&xe->usm.lock);
-	if (!vm || !xe_vm_in_fault_mode(vm))
+	if (!vm)
 		return -EINVAL;
 
 retry_userptr:
-- 
2.43.0