From: Jason Gunthorpe <jgg@mellanox.com>
Date: Mon, 2 Sep 2019 03:01:03 -0300
Subject: drm/radeon: guard against calling an unpaired radeon_mn_unregister()
Git-commit: f2bc09e9519181c7ca7ad4778d46b804c5b4c8c9
Patch-mainline: v5.4-rc1
References: jsc#SLE-16387, bsc#1152489
This check was accidently deleted in the below commit. There are cases
where the driver will call unregister even though it hasn't registered
anything.
CPU 0 Unable to handle kernel paging request at virtual address 0000001c, epc == 808de6d4, ra == 804d32ec
Call Trace:
[<808de6d4>] mutex_lock+0x8/0x44
[<804d32ec>] radeon_mn_unregister+0x3c/0xb0
[<8041583c>] radeon_gem_object_free+0x18/0x2c
[<803a451c>] drm_gem_object_release_handle+0x74/0xac
[<803a45d0>] drm_gem_handle_delete+0x7c/0x128
[<803a5bf4>] drm_ioctl_kernel+0xb0/0x108
[<803a5e74>] drm_ioctl+0x200/0x3a8
[<803e07b4>] radeon_drm_ioctl+0x54/0xc0
[<801214dc>] do_vfs_ioctl+0x4e8/0x81c
[<80121864>] ksys_ioctl+0x54/0xb0
[<8001100c>] syscall_common+0x34/0x58
Link: https://lore.kernel.org/r/2fc7ef14-e89a-1f2d-381d-1c9b05da02d3@gmail.com
Fixes: 534e5f84b7a9 ("drm/radeon: use mmu_notifier_get/put for struct radeon_mn")
Reported-by: Petr Cvek <petrcvekcz@gmail.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
---
drivers/gpu/drm/radeon/radeon_mn.c | 3 +++
1 file changed, 3 insertions(+)
--- a/drivers/gpu/drm/radeon/radeon_mn.c
+++ b/drivers/gpu/drm/radeon/radeon_mn.c
@@ -234,6 +234,9 @@ void radeon_mn_unregister(struct radeon_
struct radeon_mn *rmn = bo->mn;
struct list_head *head;
+ if (!rmn)
+ return;
+
mutex_lock(&rmn->lock);
/* save the next list entry for later */
head = bo->mn_list.next;