linux-kernel - Re: [syzbot] [dri?] WARNING in vkms_get_vblank

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Date: Wed, 07 Feb 2024 17:44:04 -0800
From: syzbot <syzbot+93bd128a383695391534@...kaller.appspotmail.com>
To: hdanton@...a.com, linux-kernel@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [dri?] WARNING in vkms_get_vblank_timestamp (2)

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
WARNING in vkms_get_vblank_timestamp

------------[ cut here ]------------
WARNING: CPU: 1 PID: 5726 at drivers/gpu/drm/vkms/vkms_crtc.c:103 vkms_get_vblank_timestamp+0x1d2/0x210 drivers/gpu/drm/vkms/vkms_crtc.c:103
Modules linked in:
CPU: 1 PID: 5726 Comm: syz-executor.5 Not tainted 6.8.0-rc3-syzkaller-g547ab8fc4cb0-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
RIP: 0010:vkms_get_vblank_timestamp+0x1d2/0x210 drivers/gpu/drm/vkms/vkms_crtc.c:103
Code: 00 74 08 48 89 ef e8 4d ea 2a fc 48 89 5d 00 b0 01 48 83 c4 08 5b 41 5c 41 5d 41 5e 41 5f 5d e9 54 73 a5 05 e8 ef 12 c9 fb 90 <0f> 0b 90 eb e0 89 d9 80 e1 07 80 c1 03 38 c1 0f 8c 74 fe ff ff 48
RSP: 0018:ffffc900093775c0 EFLAGS: 00010093
RAX: ffffffff85ca4351 RBX: 0000001c719ce79f RCX: ffff88801ab58000
RDX: 0000000000000000 RSI: 0000001c719ce79f RDI: 0000001c719ce79f
RBP: ffffc90009377690 R08: ffffffff85ca42b9 R09: fffff5200126eec0
R10: dffffc0000000000 R11: ffffffff85ca4180 R12: 0000001c719ce79f
R13: 1ffff9200126eed2 R14: 0000000000000000 R15: ffff88801f6b8000
FS:  0000555555de6480(0000) GS:ffff8880b9500000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f8f0a405f78 CR3: 000000002da42000 CR4: 0000000000350ef0
Call Trace:
 <TASK>
 drm_crtc_get_last_vbltimestamp drivers/gpu/drm/drm_vblank.c:867 [inline]
 drm_get_last_vbltimestamp drivers/gpu/drm/drm_vblank.c:886 [inline]
 drm_update_vblank_count+0x25c/0x9c0 drivers/gpu/drm/drm_vblank.c:298
 drm_vblank_disable_and_save+0xee/0x3b0 drivers/gpu/drm/drm_vblank.c:467
 drm_crtc_vblank_off+0x34a/0x990 drivers/gpu/drm/drm_vblank.c:1351
 disable_outputs drivers/gpu/drm/drm_atomic_helper.c:1213 [inline]
 drm_atomic_helper_commit_modeset_disables+0xd01/0x1a10 drivers/gpu/drm/drm_atomic_helper.c:1417
 vkms_atomic_commit_tail+0x50/0x200 drivers/gpu/drm/vkms/vkms_drv.c:71
 commit_tail+0x2ab/0x3c0 drivers/gpu/drm/drm_atomic_helper.c:1832
 drm_atomic_helper_commit+0x953/0x9f0 drivers/gpu/drm/drm_atomic_helper.c:2072
 drm_atomic_commit+0x27f/0x2d0 drivers/gpu/drm/drm_atomic.c:1514
 drm_client_modeset_commit_atomic+0x676/0x7e0 drivers/gpu/drm/drm_client_modeset.c:1051
 drm_client_modeset_commit_locked+0xe0/0x520 drivers/gpu/drm/drm_client_modeset.c:1154
 drm_client_modeset_commit+0x4a/0x70 drivers/gpu/drm/drm_client_modeset.c:1180
 __drm_fb_helper_restore_fbdev_mode_unlocked drivers/gpu/drm/drm_fb_helper.c:251 [inline]
 drm_fb_helper_restore_fbdev_mode_unlocked drivers/gpu/drm/drm_fb_helper.c:278 [inline]
 drm_fb_helper_lastclose+0xbb/0x180 drivers/gpu/drm/drm_fb_helper.c:2005
 drm_fbdev_generic_client_restore+0x34/0x40 drivers/gpu/drm/drm_fbdev_generic.c:258
 drm_client_dev_restore+0x134/0x270 drivers/gpu/drm/drm_client.c:247
 drm_lastclose drivers/gpu/drm/drm_file.c:406 [inline]
 drm_release+0x47c/0x560 drivers/gpu/drm/drm_file.c:437
 __fput+0x42b/0x8a0 fs/file_table.c:376
 __do_sys_close fs/open.c:1554 [inline]
 __se_sys_close fs/open.c:1539 [inline]
 __x64_sys_close+0x7e/0x110 fs/open.c:1539
 do_syscall_64+0xfb/0x240
 entry_SYSCALL_64_after_hwframe+0x6f/0x77
RIP: 0033:0x7f34f067cc9a
Code: 48 3d 00 f0 ff ff 77 48 c3 0f 1f 80 00 00 00 00 48 83 ec 18 89 7c 24 0c e8 03 7f 02 00 8b 7c 24 0c 89 c2 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 36 89 d7 89 44 24 0c e8 63 7f 02 00 8b 44 24
RSP: 002b:00007fffaffe38c0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 00007f34f067cc9a
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000004
RBP: 00007f34f07ad980 R08: 0000001b2f560000 R09: 00007fffafff50b0
R10: 0000000000000000 R11: 0000000000000293 R12: 000000000001dfe8
R13: ffffffffffffffff R14: 00007f34f0200000 R15: 000000000001dca7
 </TASK>


Tested on:

commit:         547ab8fc Merge tag 'loongarch-fixes-6.8-2' of git://gi..
git tree:       https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=11f9e618180000
kernel config:  https://syzkaller.appspot.com/x/.config?x=1efaddafc96fefed
dashboard link: https://syzkaller.appspot.com/bug?extid=93bd128a383695391534
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=10ddd29fe80000