WARNING: locking bug in clear_inode

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 472e5b05 pipe: remove pipe_wait() and fix wakeup race with..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12432b33900000
kernel config: https://syzkaller.appspot.com/x/.config?x=89ab6a0c48f30b49
dashboard link: https://syzkaller.appspot.com/bug?extid=4c85be59d8cc26bd485e
compiler: gcc (GCC) 10.1.0-syz 20200507
userspace arch: i386

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+4c85be...@syzkaller.appspotmail.com

------------[ cut here ]------------
DEBUG_LOCKS_WARN_ON(1)
WARNING: CPU: 0 PID: 7050 at kernel/locking/lockdep.c:183 hlock_class kernel/locking/lockdep.c:183 [inline]
WARNING: CPU: 0 PID: 7050 at kernel/locking/lockdep.c:183 hlock_class kernel/locking/lockdep.c:172 [inline]
WARNING: CPU: 0 PID: 7050 at kernel/locking/lockdep.c:183 check_wait_context kernel/locking/lockdep.c:4115 [inline]
WARNING: CPU: 0 PID: 7050 at kernel/locking/lockdep.c:183 __lock_acquire+0x15f1/0x5780 kernel/locking/lockdep.c:4391
Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: 7050 Comm: syz-executor.2 Not tainted 5.9.0-rc7-syzkaller #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+0x198/0x1fd lib/dump_stack.c:118
panic+0x382/0x7fb kernel/panic.c:231
__warn.cold+0x20/0x4b kernel/panic.c:600
report_bug+0x1bd/0x210 lib/bug.c:198
handle_bug+0x38/0x90 arch/x86/kernel/traps.c:234
exc_invalid_op+0x14/0x40 arch/x86/kernel/traps.c:254
asm_exc_invalid_op+0x12/0x20 arch/x86/include/asm/idtentry.h:536
RIP: 0010:hlock_class kernel/locking/lockdep.c:183 [inline]
RIP: 0010:hlock_class kernel/locking/lockdep.c:172 [inline]
RIP: 0010:check_wait_context kernel/locking/lockdep.c:4115 [inline]
RIP: 0010:__lock_acquire+0x15f1/0x5780 kernel/locking/lockdep.c:4391
Code: 08 84 d2 0f 85 c5 39 00 00 8b 0d c2 e6 fd 09 85 c9 0f 85 7f fa ff ff 48 c7 c6 c0 da 8b 88 48 c7 c7 80 d5 8b 88 e8 41 cb ea ff <0f> 0b e9 65 fa ff ff c7 44 24 48 fe ff ff ff 41 bf 01 00 00 00 c7
RSP: 0018:ffffc90005517818 EFLAGS: 00010082
RAX: 0000000000000000 RBX: 0000000000000001 RCX: 0000000000000000
RDX: ffff888095f94440 RSI: ffffffff815f59d5 RDI: fffff52000aa2ef5
RBP: ffff888095f94440 R08: 0000000000000000 R09: ffffffff8a05ae03
R10: 0000000000000e34 R11: 0000000000000001 R12: ffff888095f94d28
R13: 0000000000001902 R14: ffff8880004057d8 R15: 0000000000040000
lock_acquire+0x1f3/0xaf0 kernel/locking/lockdep.c:5029
__raw_spin_lock_irq include/linux/spinlock_api_smp.h:128 [inline]
_raw_spin_lock_irq+0x94/0xd0 kernel/locking/spinlock.c:167
spin_lock_irq include/linux/spinlock.h:379 [inline]
clear_inode+0x1b/0x1e0 fs/inode.c:529
proc_evict_inode+0x25/0x160 fs/proc/inode.c:40
evict+0x2ed/0x750 fs/inode.c:576
iput_final fs/inode.c:1652 [inline]
iput.part.0+0x424/0x850 fs/inode.c:1678
iput+0x58/0x70 fs/inode.c:1668
proc_invalidate_siblings_dcache+0x28d/0x600 fs/proc/inode.c:160
release_task+0xc63/0x14d0 kernel/exit.c:221
wait_task_zombie kernel/exit.c:1088 [inline]
wait_consider_task+0x2fd2/0x3b70 kernel/exit.c:1315
do_wait_thread kernel/exit.c:1378 [inline]
do_wait+0x376/0xa00 kernel/exit.c:1449
kernel_wait4+0x14c/0x260 kernel/exit.c:1621
do_syscall_32_irqs_on arch/x86/entry/common.c:78 [inline]
__do_fast_syscall_32+0x60/0x90 arch/x86/entry/common.c:137
do_fast_syscall_32+0x2f/0x70 arch/x86/entry/common.c:160
entry_SYSENTER_compat_after_hwframe+0x4d/0x5c
RIP: 0023:0xf7fc3549
Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 eb 0d 90 90 90 90 90 90 90 90 90 90 90 90
RSP: 002b:00000000090bfda4 EFLAGS: 00000216 ORIG_RAX: 0000000000000007
RAX: ffffffffffffffda RBX: 00000000ffffffff RCX: 00000000090bfe0c
RDX: 0000000040000001 RSI: 0000000000103d9b RDI: 0000000000000000
RBP: 0000000000000003 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
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.