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SubjectWARNING: bad unlock balance in rcu_core

syzbot found the following crash on:

HEAD commit: 6d0a5984 Merge branch 'x86-urgent-for-linus' of git://git...
git tree: upstream
console output:
kernel config:
dashboard link:
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

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

IMPORTANT: if you fix the bug, please add the following tag to the commit:

WARNING: bad unlock balance detected!
5.1.0-rc4+ #66 Not tainted
syz-executor.1/17297 is trying to release lock (rcu_callback) at:
[<ffffffff815f08d6>] __write_once_size include/linux/compiler.h:220 [inline]
[<ffffffff815f08d6>] __rcu_reclaim kernel/rcu/rcu.h:226 [inline]
[<ffffffff815f08d6>] rcu_do_batch kernel/rcu/tree.c:2475 [inline]
[<ffffffff815f08d6>] invoke_rcu_callbacks kernel/rcu/tree.c:2788 [inline]
[<ffffffff815f08d6>] rcu_core+0x906/0x13a0 kernel/rcu/tree.c:2769
but there are no more locks to release!

other info that might help us debug this:
1 lock held by syz-executor.1/17297:
#0: 00000000248f8dcd (&type->s_umount_key#59/1){+.+.}, at:
alloc_super+0x158/0x890 fs/super.c:228

stack backtrace:
CPU: 0 PID: 17297 Comm: syz-executor.1 Not tainted 5.1.0-rc4+ #66
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
print_unlock_imbalance_bug kernel/locking/lockdep.c:3754 [inline]
print_unlock_imbalance_bug.cold+0x114/0x123 kernel/locking/lockdep.c:3731
__lock_release kernel/locking/lockdep.c:3970 [inline]
lock_release+0x67e/0xa00 kernel/locking/lockdep.c:4230
rcu_lock_release include/linux/rcupdate.h:215 [inline]
__rcu_reclaim kernel/rcu/rcu.h:228 [inline]
rcu_do_batch kernel/rcu/tree.c:2475 [inline]
invoke_rcu_callbacks kernel/rcu/tree.c:2788 [inline]
rcu_core+0x92e/0x13a0 kernel/rcu/tree.c:2769
__do_softirq+0x266/0x95a kernel/softirq.c:293
invoke_softirq kernel/softirq.c:374 [inline]
irq_exit+0x180/0x1d0 kernel/softirq.c:414
exiting_irq arch/x86/include/asm/apic.h:536 [inline]
smp_apic_timer_interrupt+0x14a/0x570 arch/x86/kernel/apic/apic.c:1062
apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:807
RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:767
RIP: 0010:console_unlock+0xb82/0xed0 kernel/printk/printk.c:2460
Code: 92 88 48 c1 e8 03 42 80 3c 30 00 0f 85 e4 02 00 00 48 83 3d 4f fa 37
07 00 0f 84 91 01 00 00 e8 84 f0 15 00 48 8b 7d 98 57 9d <0f> 1f 44 00 00
e9 6b ff ff ff e8 6f f0 15 00 48 8b 7d 08 c7 05 11
RSP: 0018:ffff88805aa4f8d0 EFLAGS: 00000212 ORIG_RAX: ffffffffffffff13
RAX: 0000000000040000 RBX: 0000000000000200 RCX: ffffc90008209000
RDX: 00000000000101de RSI: ffffffff815a9c2c RDI: 0000000000000212
RBP: ffff88805aa4f958 R08: ffff888099a66100 R09: fffffbfff11335b9
R10: fffffbfff11335b8 R11: 0000000000000001 R12: 0000000000000000
R13: ffffffff84210cf0 R14: dffffc0000000000 R15: ffffffff88f90710
vprintk_emit+0x280/0x6d0 kernel/printk/printk.c:1975
vprintk_default+0x28/0x30 kernel/printk/printk.c:2002
vprintk_func+0x7e/0x189 kernel/printk/printk_safe.c:398
printk+0xba/0xed kernel/printk/printk.c:2035
__ntfs_error.cold+0x91/0xc7 fs/ntfs/debug.c:103
ntfs_fill_super+0x2015/0x3150 fs/ntfs/super.c:2792
mount_bdev+0x307/0x3c0 fs/super.c:1346
ntfs_mount+0x35/0x40 fs/ntfs/super.c:3065
legacy_get_tree+0xf2/0x200 fs/fs_context.c:584
vfs_get_tree+0x123/0x450 fs/super.c:1481
do_new_mount fs/namespace.c:2622 [inline]
do_mount+0x1436/0x2c40 fs/namespace.c:2942
ksys_mount+0xdb/0x150 fs/namespace.c:3151
__do_sys_mount fs/namespace.c:3165 [inline]
__se_sys_mount fs/namespace.c:3162 [inline]
__x64_sys_mount+0xbe/0x150 fs/namespace.c:3162
do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
RIP: 0033:0x45b69a
Code: b8 a6 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 2d 8e fb ff c3 66 2e 0f
1f 84 00 00 00 00 00 66 90 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff
ff 0f 83 0a 8e fb ff c3 66 0f 1f 84 00 00 00 00 00
RSP: 002b:00007f2f99d0ba88 EFLAGS: 00000206 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f2f99d0bb40 RCX: 000000000045b69a
RDX: 00007f2f99d0bae0 RSI: 0000000020000140 RDI: 00007f2f99d0bb00
RBP: 0000000000000000 R08: 00007f2f99d0bb40 R09: 00007f2f99d0bae0
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000008
R13: 00000000004c7802 R14: 00000000004dd850 R15: 00000000ffffffff

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