Re: drm/ttm: ttm_bo_release called without lock

[Petr Mladek]

On Wed 2021-03-03 15:34:09, Petr Mladek wrote:
> Hi,
> 
> the following warning is filling my kernel log buffer
> with 5.12-rc1+ kernels:
> 
> [  941.070598] WARNING: CPU: 0 PID: 11 at drivers/gpu/drm/ttm/ttm_bo.c:139 ttm_bo_move_to_lru_tail+0x1ba/0x210
> [  941.070601] Modules linked in:
> [  941.070603] CPU: 0 PID: 11 Comm: kworker/0:1 Kdump: loaded Tainted: G        W         5.12.0-rc1-default+ #81
> [  941.070605] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.12.0-59-gc9ba527-rebuilt.opensuse.org 04/01/2014
> [  941.070606] Workqueue: events qxl_gc_work
> [  941.070609] RIP: 0010:ttm_bo_move_to_lru_tail+0x1ba/0x210
> [  941.070610] Code: 93 e8 02 00 00 48 89 0a e9 00 ff ff ff 48 8b 87 38 01 00 00 be ff ff ff ff 48 8d 78 70 e8 8e 7d 46 00 85 c0 0f 85 6f fe ff ff <0f> 0b 8b 93 fc 02 00 00 85 d2 0f 84 6d fe ff ff 48 89 df 5b 5d 41
> [  941.070612] RSP: 0018:ffffbddf4008fd38 EFLAGS: 00010246
> [  941.070614] RAX: 0000000000000000 RBX: ffff95ae485bac00 RCX: 0000000000000002
> [  941.070615] RDX: 0000000000000000 RSI: ffff95ae485badb0 RDI: ffff95ae40305108
> [  941.070616] RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000001
> [  941.070617] R10: ffffbddf4008fc10 R11: ffffffffa5401580 R12: ffff95ae42a94e90
> [  941.070618] R13: ffff95ae485bae70 R14: ffff95ae485bac00 R15: ffff95ae455d1800
> [  941.070620] FS:  0000000000000000(0000) GS:ffff95aebf600000(0000) knlGS:0000000000000000
> [  941.070621] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [  941.070622] CR2: 00007f8ffb2f8000 CR3: 0000000102c5e005 CR4: 0000000000370ef0
> [  941.070624] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> [  941.070626] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> [  941.070627] Call Trace:
> [  941.070630]  ttm_bo_release+0x551/0x600
> [  941.070635]  qxl_bo_unref+0x3a/0x50
> [  941.070638]  qxl_release_free_list+0x62/0xc0
> [  941.070643]  qxl_release_free+0x76/0xe0
> [  941.070646]  qxl_garbage_collect+0xd9/0x190
> [  941.080241]  process_one_work+0x2b0/0x630
> [  941.080249]  ? process_one_work+0x630/0x630
> [  941.080251]  worker_thread+0x39/0x3f0
> [  941.080255]  ? process_one_work+0x630/0x630
> [  941.080257]  kthread+0x13a/0x150
> [  941.080260]  ? kthread_create_worker_on_cpu+0x70/0x70
> [  941.080265]  ret_from_fork+0x1f/0x30
> [  941.080277] irq event stamp: 757191
> [  941.080278] hardirqs last  enabled at (757197): [<ffffffffa217431f>] vprintk_emit+0x27f/0x2c0
> [  941.080280] hardirqs last disabled at (757202): [<ffffffffa21742dc>] vprintk_emit+0x23c/0x2c0
> [  941.080281] softirqs last  enabled at (755768): [<ffffffffa300030f>] __do_softirq+0x30f/0x432
> [  941.080284] softirqs last disabled at (755763): [<ffffffffa20eb0aa>] irq_exit_rcu+0xea/0xf0

I have just realized that it actually prints two warnings over and
over again. The 2nd one is:

[  186.078790] WARNING: CPU: 0 PID: 146 at drivers/gpu/drm/ttm/ttm_bo.c:512 ttm_bo_release+0x533/0x600
[  186.078794] Modules linked in:
[  186.078795] CPU: 0 PID: 146 Comm: kworker/0:2 Kdump: loaded Tainted: G        W         5.12.0-rc1-default+ #81
[  186.078797] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.12.0-59-gc9ba527-rebuilt.opensuse.org 04/01/2014
[  186.078799] Workqueue: events qxl_gc_work
[  186.078801] RIP: 0010:ttm_bo_release+0x533/0x600
[  186.078803] Code: e9 c6 fb ff ff 4c 8b 7d d0 b9 4c 1d 00 00 31 d2 be 01 00 00 00 49 8b bf d0 fe ff ff e8 86 f1 04 00 49 8b 
47 e0 e9 2b ff ff ff <0f> 0b 48 8b 45 d0 31 d2 4c 89 f7 48 8d 70 08 c7 80 94 00 00 00 00
[  186.078805] RSP: 0018:ffffa22a402e3d60 EFLAGS: 00010202
[  186.078807] RAX: 0000000000000001 RBX: ffff9334cd8f5668 RCX: 0000000000001180
[  186.078808] RDX: ffff93353f61a7c0 RSI: ffffffffa6401580 RDI: ffff9334c44f9588
[  186.078810] RBP: ffffa22a402e3d90 R08: 0000000000000001 R09: 0000000000000001
[  186.078811] R10: ffffa22a402e3c10 R11: ffffffffa6401580 R12: ffff9334c48fa300
[  186.078812] R13: ffff9334c0f24e90 R14: ffff9334cd8f5400 R15: ffff9334c4528000
[  186.078813] FS:  0000000000000000(0000) GS:ffff93353f600000(0000) knlGS:0000000000000000
[  186.078814] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  186.078816] CR2: 00007f1908079860 CR3: 0000000021824004 CR4: 0000000000370ef0
[  186.078818] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  186.078819] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[  186.078821] Call Trace:
[  186.078826]  qxl_bo_unref+0x3a/0x50
[  186.078829]  qxl_release_free_list+0x62/0xc0
[  186.078834]  qxl_release_free+0x76/0xe0
[  186.078837]  qxl_garbage_collect+0xd9/0x190
[  186.078843]  process_one_work+0x2b0/0x630
[  186.078850]  ? process_one_work+0x630/0x630
[  186.078853]  worker_thread+0x39/0x3f0
[  186.078857]  ? process_one_work+0x630/0x630
[  186.078859]  kthread+0x13a/0x150
[  186.078861]  ? kthread_create_worker_on_cpu+0x70/0x70
[  186.078866]  ret_from_fork+0x1f/0x30
[  186.078879] irq event stamp: 619687
[  186.091417] hardirqs last  enabled at (619761): [<ffffffffa317293b>] console_unlock+0x45b/0x570
[  186.091421] hardirqs last disabled at (619766): [<ffffffffa31742dc>] vprintk_emit+0x23c/0x2c0
[  186.091423] softirqs last  enabled at (617742): [<ffffffffa400030f>] __do_softirq+0x30f/0x432
[  186.091425] softirqs last disabled at (617737): [<ffffffffa30eb0aa>] irq_exit_rcu+0xea/0xf0
[  186.091427] ---[ end trace ac74376b06d2036c ]---


Tke kernel is based on Linus' tree and the last commit
f69d02e37a85645aa90d1 ("Merge tag 'misc-5.12-2021-03-02' of
git://git.kernel.dk/linux-block").

Best Regards,
Petr