[PATCH] drm/amdgpu: fix kernel page fault issue by ras recovery on sGPU

[Clements, John]

[AMD Official Use Only - Internal Distribution Only]

Reviewed-by: John Clements <John.Clements at amd.com>

-----Original Message-----
From: Chen, Guchun <Guchun.Chen at amd.com> 
Sent: Thursday, April 16, 2020 11:48 PM
To: amd-gfx at lists.freedesktop.org; Zhang, Hawking <Hawking.Zhang at amd.com>; Li, Dennis <Dennis.Li at amd.com>; Clements, John <John.Clements at amd.com>
Cc: Chen, Guchun <Guchun.Chen at amd.com>
Subject: [PATCH] drm/amdgpu: fix kernel page fault issue by ras recovery on sGPU

When running ras uncorrectable error injection and trigger GPU reset on sGPU, below issue is observed. It's caused by the list uninitialized when accessing.

[   80.047227] BUG: unable to handle page fault for address: ffffffffc0f4f750
[   80.047300] #PF: supervisor write access in kernel mode
[   80.047351] #PF: error_code(0x0003) - permissions violation
[   80.047404] PGD 12c20e067 P4D 12c20e067 PUD 12c210067 PMD 41c4ee067 PTE 404316061
[   80.047477] Oops: 0003 [#1] SMP PTI
[   80.047516] CPU: 7 PID: 377 Comm: kworker/7:2 Tainted: G           OE     5.4.0-rc7-guchchen #1
[   80.047594] Hardware name: System manufacturer System Product Name/TUF Z370-PLUS GAMING II, BIOS 0411 09/21/2018
[   80.047888] Workqueue: events amdgpu_ras_do_recovery [amdgpu]

Signed-off-by: Guchun Chen <guchun.chen at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c
index b27d9d62c9df..260b4a42e0ae 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c
@@ -1448,9 +1448,10 @@ static void amdgpu_ras_do_recovery(struct work_struct *work)
 	struct amdgpu_hive_info *hive = amdgpu_get_xgmi_hive(adev, false);
 
 	/* Build list of devices to query RAS related errors */
-	if  (hive && adev->gmc.xgmi.num_physical_nodes > 1) {
+	if  (hive && adev->gmc.xgmi.num_physical_nodes > 1)
 		device_list_handle = &hive->device_list;
-	} else {
+	else {
+		INIT_LIST_HEAD(&device_list);
 		list_add_tail(&adev->gmc.xgmi.head, &device_list);
 		device_list_handle = &device_list;
 	}
--
2.17.1