WARNING in vkms_gem_free_object

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 8ada228a Add linux-next specific files for 20191011
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=14c30b1b600000
kernel config: https://syzkaller.appspot.com/x/.config?x=7cf4eed5fe42c31a
dashboard link: https://syzkaller.appspot.com/bug?extid=e7ad70d406e74d8fc9d0
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1087d31b600000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15e27c53600000

The bug was bisected to:

commit 94e2ec3f7fef86506293a448273b2b4ee21e6195
Author: Oleg Vasilev <omri...@gmail.com>
Date: Mon Sep 30 15:59:24 2019 +0000

drm/vkms: prime import support

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=15ef2d57600000
final crash: https://syzkaller.appspot.com/x/report.txt?x=17ef2d57600000
console output: https://syzkaller.appspot.com/x/log.txt?x=13ef2d57600000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+e7ad70...@syzkaller.appspotmail.com
Fixes: 94e2ec3f7fef ("drm/vkms: prime import support")

------------[ cut here ]------------
WARNING: CPU: 1 PID: 9040 at drivers/gpu/drm/vkms/vkms_gem.c:37
vkms_gem_free_object+0x92/0xb0 drivers/gpu/drm/vkms/vkms_gem.c:37
Kernel panic - not syncing: panic_on_warn set ...
CPU: 1 PID: 9040 Comm: syz-executor028 Not tainted 5.4.0-rc2-next-20191011
#0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x172/0x1f0 lib/dump_stack.c:113
panic+0x2e3/0x75c kernel/panic.c:221
__warn.cold+0x2f/0x35 kernel/panic.c:582
report_bug+0x289/0x300 lib/bug.c:195
fixup_bug arch/x86/kernel/traps.c:174 [inline]
fixup_bug arch/x86/kernel/traps.c:169 [inline]
do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:267
do_invalid_op+0x37/0x50 arch/x86/kernel/traps.c:286
invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1028
RIP: 0010:vkms_gem_free_object+0x92/0xb0 drivers/gpu/drm/vkms/vkms_gem.c:37
Code: 44 68 7f fd 49 8d bc 24 f8 01 00 00 e8 c7 8d 64 fd 4c 89 e7 e8 3f 39
ae ff 4c 89 e7 e8 f7 9a ba fd 41 5c 5d c3 e8 1e 68 7f fd <0f> 0b eb a2 e8
15 68 7f fd 0f 0b eb c8 e8 2c e7 ba fd eb b6 e8 25
RSP: 0018:ffff8880971df9e8 EFLAGS: 00010293
RAX: ffff8880989c2200 RBX: ffffffff894e5000 RCX: ffffffff83a1eda6
RDX: 0000000000000000 RSI: ffffffff83f3ab02 RDI: ffff8880a8c4fa78
RBP: ffff8880971df9f0 R08: ffff8880989c2200 R09: ffffed1012e3bf36
R10: ffffed1012e3bf35 R11: 0000000000000003 R12: ffff8880a8c4f800
R13: ffff8880a3ab8000 R14: ffffffff83f3aa70 R15: ffff8880a3ab8020
drm_gem_object_free+0x100/0x220 drivers/gpu/drm/drm_gem.c:983
kref_put include/linux/kref.h:65 [inline]
drm_gem_object_put_unlocked drivers/gpu/drm/drm_gem.c:1017 [inline]
drm_gem_object_put_unlocked+0x127/0x170 drivers/gpu/drm/drm_gem.c:1002
drm_gem_object_handle_put_unlocked+0x1ad/0x2d0
drivers/gpu/drm/drm_gem.c:239
drm_gem_object_release_handle+0x102/0x1c0 drivers/gpu/drm/drm_gem.c:261
idr_for_each+0x138/0x250 lib/idr.c:208
drm_gem_release+0x27/0x40 drivers/gpu/drm/drm_gem.c:939
drm_file_free.part.0+0x7f4/0xc00 drivers/gpu/drm/drm_file.c:244
drm_file_free drivers/gpu/drm/drm_file.c:213 [inline]
drm_close_helper drivers/gpu/drm/drm_file.c:271 [inline]
drm_release+0x286/0x3f0 drivers/gpu/drm/drm_file.c:443
__fput+0x2ff/0x890 fs/file_table.c:280
____fput+0x16/0x20 fs/file_table.c:313
task_work_run+0x145/0x1c0 kernel/task_work.c:113
exit_task_work include/linux/task_work.h:22 [inline]
do_exit+0x904/0x2e60 kernel/exit.c:817
do_group_exit+0x135/0x360 kernel/exit.c:921
__do_sys_exit_group kernel/exit.c:932 [inline]
__se_sys_exit_group kernel/exit.c:930 [inline]
__x64_sys_exit_group+0x44/0x50 kernel/exit.c:930
do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x442bb8
Code: Bad RIP value.
RSP: 002b:00007ffd8fdc0b98 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000442bb8
RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000
RBP: 00000000004c24c8 R08: 00000000000000e7 R09: ffffffffffffffd0
R10: 00000000004002e0 R11: 0000000000000246 R12: 0000000000000001
R13: 00000000006d41a0 R14: 0000000000000000 R15: 0000000000000000
Kernel Offset: disabled
Rebooting in 86400 seconds..


---
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For information about bisection process see: https://goo.gl/tpsmEJ#bisection
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[Daniel Vetter]

On Sun, Oct 13, 2019 at 07:49:08PM -0700, syzbot wrote:
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit: 8ada228a Add linux-next specific files for 20191011
> git tree: linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=14c30b1b600000
> kernel config: https://syzkaller.appspot.com/x/.config?x=7cf4eed5fe42c31a
> dashboard link: https://syzkaller.appspot.com/bug?extid=e7ad70d406e74d8fc9d0
> compiler: gcc (GCC) 9.0.0 20181231 (experimental)
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1087d31b600000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15e27c53600000
>
> The bug was bisected to:
>
> commit 94e2ec3f7fef86506293a448273b2b4ee21e6195
> Author: Oleg Vasilev <omri...@gmail.com>
> Date: Mon Sep 30 15:59:24 2019 +0000
>
> drm/vkms: prime import support
>
> bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=15ef2d57600000
> final crash: https://syzkaller.appspot.com/x/report.txt?x=17ef2d57600000
> console output: https://syzkaller.appspot.com/x/log.txt?x=13ef2d57600000
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+e7ad70...@syzkaller.appspotmail.com
> Fixes: 94e2ec3f7fef ("drm/vkms: prime import support")

Oleg, will you be looking at this? With the reproducer and full drm
debugging enabled it shouldn't be too hard to figure out what's going on
heere ...
-Daniel

--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

[Simon Ser]

On Monday, October 14, 2019 12:17 PM, Daniel Vetter <dan...@ffwll.ch> wrote:

> Oleg, will you be looking at this? With the reproducer and full drm
> debugging enabled it shouldn't be too hard to figure out what's going on
> heere ...

Oleg is no longer working at Intel. I don't think he monitors dri-devel
anymore.

I'd like to work on VKMS myself, but it's very unlikely I have time to
do so anytime soon.

(Neither Oleg nor I have access to our @intel.com address anymore.)

[syzbot]

Auto-closing this bug as obsolete.
No recent activity, existing reproducers are no longer triggering the issue.