WARNING: ODEBUG bug in sock_destroy_inode

[syzbot]

Hello,

syzbot hit the following crash on upstream commit
b5dbc28762fd3fd40ba76303be0c7f707826f982 (Sat Mar 31 04:53:57 2018 +0000)
Merge tag 'kbuild-fixes-v4.16-3' of
git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild
syzbot dashboard link:
https://syzkaller.appspot.com/bug?extid=df3b19d8fe2f2079d0cc

Unfortunately, I don't have any reproducer for this crash yet.
Raw console output:
https://syzkaller.appspot.com/x/log.txt?id=4971665893097472
Kernel config:
https://syzkaller.appspot.com/x/.config?id=-2760467897697295172
compiler: gcc (GCC) 7.1.1 20170620
CC: [da...@davemloft.net linux-...@vger.kernel.org
net...@vger.kernel.org]

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+df3b19...@syzkaller.appspotmail.com
It will help syzbot understand when the bug is fixed. See footer for
details.
If you forward the report, please keep this part and the footer.

------------[ cut here ]------------
ODEBUG: activate active (active state 1) object type: rcu_head
hint: (null)
WARNING: CPU: 1 PID: 4450 at lib/debugobjects.c:291
debug_print_object+0x166/0x220 lib/debugobjects.c:288
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 4450 Comm: syz-executor4 Not tainted 4.16.0-rc7+ #373
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x194/0x24d lib/dump_stack.c:53
panic+0x1e4/0x41c kernel/panic.c:183
__warn+0x1dc/0x200 kernel/panic.c:547
report_bug+0x1f4/0x2b0 lib/bug.c:186
fixup_bug.part.10+0x37/0x80 arch/x86/kernel/traps.c:178
fixup_bug arch/x86/kernel/traps.c:247 [inline]
do_error_trap+0x2d7/0x3e0 arch/x86/kernel/traps.c:296
do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:315
invalid_op+0x1b/0x40 arch/x86/entry/entry_64.S:986
RIP: 0010:debug_print_object+0x166/0x220 lib/debugobjects.c:288
RSP: 0018:ffff8801842870c0 EFLAGS: 00010086
RAX: dffffc0000000008 RBX: 0000000000000003 RCX: ffffffff815b193e
RDX: 0000000000000000 RSI: 1ffff10030850dc8 RDI: 1ffff10030850d9d
RBP: ffff880184287100 R08: 0000000000000000 R09: 1ffff10030850d6f
R10: ffff880184286fc0 R11: ffffffff88583158 R12: 0000000000000001
R13: ffffffff8858c2a0 R14: ffffffff8775c0c0 R15: 0000000000000000
debug_object_activate+0x49b/0x730 lib/debugobjects.c:444
debug_rcu_head_queue kernel/rcu/rcu.h:129 [inline]
__call_rcu.constprop.67+0xf2/0xef0 kernel/rcu/tree.c:3021
kfree_call_rcu+0x15/0x20 kernel/rcu/tree.c:3142
sock_destroy_inode+0x47/0x70 net/socket.c:273
destroy_inode+0x15d/0x200 fs/inode.c:266
evict+0x57e/0x920 fs/inode.c:570
iput_final fs/inode.c:1515 [inline]
iput+0x7b9/0xaf0 fs/inode.c:1542
dentry_unlink_inode+0x4b0/0x5e0 fs/dcache.c:371
__dentry_kill+0x3de/0x700 fs/dcache.c:575
dentry_kill fs/dcache.c:616 [inline]
dput.part.20+0x6fb/0x830 fs/dcache.c:831
dput+0x1f/0x30 fs/dcache.c:795
__fput+0x51c/0x7e0 fs/file_table.c:227
____fput+0x15/0x20 fs/file_table.c:243
task_work_run+0x199/0x270 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:191 [inline]
exit_to_usermode_loop+0x275/0x2f0 arch/x86/entry/common.c:166
prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline]
syscall_return_slowpath arch/x86/entry/common.c:265 [inline]
do_syscall_64+0x6ec/0x940 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x40ef30
RSP: 002b:0000000000a3eab8 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 00000000000003b1 RCX: 000000000040ef30
RDX: 00000000000000e0 RSI: 0000000000a3f960 RDI: 0000000000000013
RBP: 0000000000000001 R08: 0000000000a3eadc R09: 0000000000000001
R10: 0000000000a3f160 R11: 0000000000000246 R12: 0000000000000013
R13: 00000000006fcfe8 R14: 00000000006fd6e0 R15: 0000000000001380

======================================================
WARNING: possible circular locking dependency detected
4.16.0-rc7+ #373 Not tainted
------------------------------------------------------
syz-executor4/4450 is trying to acquire lock:
((console_sem).lock){-.-.}, at: [<00000000bd2d6a75>]
down_trylock+0x13/0x70 kernel/locking/semaphore.c:136

but task is already holding lock:
(&obj_hash[i].lock){-.-.}, at: [<00000000842b33c5>]
debug_object_activate+0x1d7/0x730 lib/debugobjects.c:432

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&obj_hash[i].lock){-.-.}:
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x96/0xc0 kernel/locking/spinlock.c:152
__debug_object_init+0x109/0x1040 lib/debugobjects.c:343
debug_object_init+0x17/0x20 lib/debugobjects.c:391
debug_hrtimer_init kernel/time/hrtimer.c:410 [inline]
debug_init kernel/time/hrtimer.c:458 [inline]
hrtimer_init+0x8c/0x410 kernel/time/hrtimer.c:1259
init_dl_task_timer+0x1b/0x50 kernel/sched/deadline.c:1060
__sched_fork+0x2bb/0xb60 kernel/sched/core.c:2189
init_idle+0x75/0x820 kernel/sched/core.c:5352
sched_init+0xb19/0xc43 kernel/sched/core.c:6049
start_kernel+0x452/0x819 init/main.c:586
x86_64_start_reservations+0x2a/0x2c arch/x86/kernel/head64.c:378
x86_64_start_kernel+0x77/0x7a arch/x86/kernel/head64.c:359
secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:239

-> #2 (&rq->lock){-.-.}:
__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:144
rq_lock kernel/sched/sched.h:1760 [inline]
task_fork_fair+0x7a/0x690 kernel/sched/fair.c:9471
sched_fork+0x450/0xc10 kernel/sched/core.c:2405
copy_process.part.38+0x17c9/0x4bd0 kernel/fork.c:1763
copy_process kernel/fork.c:1606 [inline]
_do_fork+0x1f7/0xf70 kernel/fork.c:2087
kernel_thread+0x34/0x40 kernel/fork.c:2146
rest_init+0x22/0xf0 init/main.c:403
start_kernel+0x7f1/0x819 init/main.c:717
x86_64_start_reservations+0x2a/0x2c arch/x86/kernel/head64.c:378
x86_64_start_kernel+0x77/0x7a arch/x86/kernel/head64.c:359
secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:239

-> #1 (&p->pi_lock){-.-.}:
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x96/0xc0 kernel/locking/spinlock.c:152
try_to_wake_up+0xbc/0x15f0 kernel/sched/core.c:1989
wake_up_process+0x10/0x20 kernel/sched/core.c:2152
__up.isra.0+0x1cc/0x2c0 kernel/locking/semaphore.c:262
up+0x13b/0x1d0 kernel/locking/semaphore.c:187
__up_console_sem+0xb2/0x1a0 kernel/printk/printk.c:242
console_unlock+0x5af/0xfb0 kernel/printk/printk.c:2417
do_con_write+0x106e/0x1f70 drivers/tty/vt/vt.c:2433
con_write+0x25/0xb0 drivers/tty/vt/vt.c:2782
process_output_block drivers/tty/n_tty.c:579 [inline]
n_tty_write+0x5ef/0xec0 drivers/tty/n_tty.c:2308
do_tty_write drivers/tty/tty_io.c:958 [inline]
tty_write+0x3fa/0x840 drivers/tty/tty_io.c:1042
__vfs_write+0xef/0x970 fs/read_write.c:480
vfs_write+0x189/0x510 fs/read_write.c:544
SYSC_write fs/read_write.c:589 [inline]
SyS_write+0xef/0x220 fs/read_write.c:581
do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
entry_SYSCALL_64_after_hwframe+0x42/0xb7

-> #0 ((console_sem).lock){-.-.}:
lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:3920
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x96/0xc0 kernel/locking/spinlock.c:152
down_trylock+0x13/0x70 kernel/locking/semaphore.c:136
__down_trylock_console_sem+0xa2/0x1e0 kernel/printk/printk.c:225
console_trylock+0x15/0x70 kernel/printk/printk.c:2229
console_trylock_spinning kernel/printk/printk.c:1643 [inline]
vprintk_emit+0x5b5/0xb90 kernel/printk/printk.c:1906
vprintk_default+0x28/0x30 kernel/printk/printk.c:1947
vprintk_func+0x57/0xc0 kernel/printk/printk_safe.c:379
printk+0xaa/0xca kernel/printk/printk.c:1980
__warn_printk+0x90/0xf0 kernel/panic.c:599
debug_print_object+0x166/0x220 lib/debugobjects.c:288
debug_object_activate+0x49b/0x730 lib/debugobjects.c:444
debug_rcu_head_queue kernel/rcu/rcu.h:129 [inline]
__call_rcu.constprop.67+0xf2/0xef0 kernel/rcu/tree.c:3021
kfree_call_rcu+0x15/0x20 kernel/rcu/tree.c:3142
sock_destroy_inode+0x47/0x70 net/socket.c:273
destroy_inode+0x15d/0x200 fs/inode.c:266
evict+0x57e/0x920 fs/inode.c:570
iput_final fs/inode.c:1515 [inline]
iput+0x7b9/0xaf0 fs/inode.c:1542
dentry_unlink_inode+0x4b0/0x5e0 fs/dcache.c:371
__dentry_kill+0x3de/0x700 fs/dcache.c:575
dentry_kill fs/dcache.c:616 [inline]
dput.part.20+0x6fb/0x830 fs/dcache.c:831
dput+0x1f/0x30 fs/dcache.c:795
__fput+0x51c/0x7e0 fs/file_table.c:227
____fput+0x15/0x20 fs/file_table.c:243
task_work_run+0x199/0x270 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:191 [inline]
exit_to_usermode_loop+0x275/0x2f0 arch/x86/entry/common.c:166
prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline]
syscall_return_slowpath arch/x86/entry/common.c:265 [inline]
do_syscall_64+0x6ec/0x940 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7

other info that might help us debug this:

Chain exists of:
(console_sem).lock --> &rq->lock --> &obj_hash[i].lock

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&obj_hash[i].lock);
lock(&rq->lock);
lock(&obj_hash[i].lock);
lock((console_sem).lock);

*** DEADLOCK ***

1 lock held by syz-executor4/4450:
#0: (&obj_hash[i].lock){-.-.}, at: [<00000000842b33c5>]
debug_object_activate+0x1d7/0x730 lib/debugobjects.c:432

stack backtrace:
CPU: 1 PID: 4450 Comm: syz-executor4 Not tainted 4.16.0-rc7+ #373
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x194/0x24d lib/dump_stack.c:53
print_circular_bug.isra.38+0x2cd/0x2dc kernel/locking/lockdep.c:1223
check_prev_add kernel/locking/lockdep.c:1863 [inline]
check_prevs_add kernel/locking/lockdep.c:1976 [inline]
validate_chain kernel/locking/lockdep.c:2417 [inline]
__lock_acquire+0x30a8/0x3e00 kernel/locking/lockdep.c:3431
lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:3920
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x96/0xc0 kernel/locking/spinlock.c:152
down_trylock+0x13/0x70 kernel/locking/semaphore.c:136
__down_trylock_console_sem+0xa2/0x1e0 kernel/printk/printk.c:225
console_trylock+0x15/0x70 kernel/printk/printk.c:2229
console_trylock_spinning kernel/printk/printk.c:1643 [inline]
vprintk_emit+0x5b5/0xb90 kernel/printk/printk.c:1906
vprintk_default+0x28/0x30 kernel/printk/printk.c:1947
vprintk_func+0x57/0xc0 kernel/printk/printk_safe.c:379
printk+0xaa/0xca kernel/printk/printk.c:1980
__warn_printk+0x90/0xf0 kernel/panic.c:599
debug_print_object+0x166/0x220 lib/debugobjects.c:288
debug_object_activate+0x49b/0x730 lib/debugobjects.c:444
debug_rcu_head_queue kernel/rcu/rcu.h:129 [inline]
__call_rcu.constprop.67+0xf2/0xef0 kernel/rcu/tree.c:3021
kfree_call_rcu+0x15/0x20 kernel/rcu/tree.c:3142
sock_destroy_inode+0x47/0x70 net/socket.c:273
destroy_inode+0x15d/0x200 fs/inode.c:266
evict+0x57e/0x920 fs/inode.c:570
iput_final fs/inode.c:1515 [inline]
iput+0x7b9/0xaf0 fs/inode.c:1542
dentry_unlink_inode+0x4b0/0x5e0 fs/dcache.c:371
__dentry_kill+0x3de/0x700 fs/dcache.c:575
dentry_kill fs/dcache.c:616 [inline]
dput.part.20+0x6fb/0x830 fs/dcache.c:831
dput+0x1f/0x30 fs/dcache.c:795
__fput+0x51c/0x7e0 fs/file_table.c:227
____fput+0x15/0x20 fs/file_table.c:243
task_work_run+0x199/0x270 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:191 [inline]
exit_to_usermode_loop+0x275/0x2f0 arch/x86/entry/common.c:166
prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline]
syscall_return_slowpath arch/x86/entry/common.c:265 [inline]
do_syscall_64+0x6ec/0x940 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033
Lost 7 message(s)!
Shutting down cpus with NMI
Dumping ftrace buffer:
(ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..


---
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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.