[syzbot] [mm?] WARNING: bad unlock balance in finish_fault

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 897d54018cc9 Merge tag 'fbdev-for-7.1-rc1-2' of git://git...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=158df1ba580000
kernel config: https://syzkaller.appspot.com/x/.config?x=59da38148f3a3d24
dashboard link: https://syzkaller.appspot.com/bug?extid=8caf74f5399ee2d5212b
compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44

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

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-897d5401.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/20848bcda8fe/vmlinux-897d5401.xz
kernel image: https://storage.googleapis.com/syzbot-assets/2351a3d1bb73/bzImage-897d5401.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8caf74...@syzkaller.appspotmail.com

=====================================
WARNING: bad unlock balance detected!
syzkaller #0 Not tainted
-------------------------------------
cmp/5659 is trying to release lock (rcu_read_lock) at:
[<ffffffff82595f6d>] rcu_read_unlock+0x2d/0xb0 include/linux/rcupdate.h:867
but there are no more locks to release!

other info that might help us debug this:
1 lock held by cmp/5659:
#0: ffff88803accd848 (vm_lock){++++}-{0:0}, at: lock_vma_under_rcu+0x11d/0x590 mm/mmap_lock.c:310

stack backtrace:
CPU: 2 UID: 0 PID: 5659 Comm: cmp Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
print_unlock_imbalance_bug.part.0+0xfb/0x106 kernel/locking/lockdep.c:5298
print_unlock_imbalance_bug kernel/locking/lockdep.c:5278 [inline]
__lock_release kernel/locking/lockdep.c:5537 [inline]
lock_release kernel/locking/lockdep.c:5889 [inline]
lock_release+0x28d/0x310 kernel/locking/lockdep.c:5875
rcu_read_unlock+0x32/0xb0 include/linux/rcupdate.h:867
pte_unmap include/linux/pgtable.h:117 [inline]
finish_fault+0x8ed/0x1400 mm/memory.c:5763
do_cow_fault mm/memory.c:5935 [inline]
do_fault+0xff2/0x1750 mm/memory.c:6029
do_pte_missing mm/memory.c:4550 [inline]
handle_pte_fault mm/memory.c:6411 [inline]
__handle_mm_fault+0x187d/0x2a00 mm/memory.c:6549
handle_mm_fault+0x36d/0xa20 mm/memory.c:6718
do_user_addr_fault+0x5a3/0x12f0 arch/x86/mm/fault.c:1334
handle_page_fault arch/x86/mm/fault.c:1474 [inline]
exc_page_fault+0x6f/0xd0 arch/x86/mm/fault.c:1527
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618
RIP: 0033:0x7fd47fe2aff2
Code: 0f 60 c0 66 0f 61 c0 66 0f 70 c0 00 48 83 fa 10 72 76 48 83 fa 20 77 12 0f 11 44 17 f0 0f 11 07 c3 0f 11 47 e0 0f 11 47 f0 c3 <0f> 11 07 0f 11 47 10 48 01 d7 48 83 fa 40 76 e7 0f 11 40 20 0f 11
RSP: 002b:00007ffcb5d4bcd8 EFLAGS: 00010206
RAX: 00007fd47fb30068 RBX: 0000000000000004 RCX: 00007fd47fb326d0
RDX: 0000000000000f98 RSI: 0000000000000000 RDI: 00007fd47fb30068
RBP: 00007ffcb5d4c0a0 R08: 00007fd47fb30068 R09: 0000000000000003
R10: 0000000000000812 R11: 00007ffcb5d4c188 R12: 00007ffcb5d4bd88
R13: 00007fd47fdffab0 R14: 00007ffcb5d4c140 R15: 00007fd47fb31000
</TASK>
------------[ cut here ]------------
rrln < 0 || rrln > RCU_NEST_PMAX
WARNING: kernel/rcu/tree_plugin.h:443 at __rcu_read_unlock kernel/rcu/tree_plugin.h:443 [inline], CPU#2: cmp/5659
WARNING: kernel/rcu/tree_plugin.h:443 at __rcu_read_unlock+0x235/0x5e0 kernel/rcu/tree_plugin.h:430, CPU#2: cmp/5659
Modules linked in:
CPU: 2 UID: 0 PID: 5659 Comm: cmp Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:__rcu_read_unlock kernel/rcu/tree_plugin.h:443 [inline]
RIP: 0010:__rcu_read_unlock+0x235/0x5e0 kernel/rcu/tree_plugin.h:430
Code: 74 11 c7 45 58 01 00 00 00 bf 09 00 00 00 e8 c2 6f da ff e8 9d ff 22 00 9c 58 f6 c4 02 0f 85 dd 02 00 00 fb e9 57 fe ff ff 90 <0f> 0b 90 5b 5d 41 5c 41 5d 41 5e 41 5f c3 cc cc cc cc e8 54 76 88
RSP: 0000:ffffc90003a27b28 EFLAGS: 00010286
RAX: 00000000ffffffff RBX: ffff888029db4a00 RCX: ffffffff81e7b7ae
RDX: 0000000000000000 RSI: ffffffff8def8e2a RDI: ffff888029db4ec4
RBP: ffff88802bdd4980 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000080000000 R11: 0000000000000012 R12: ffff88802bf53d40
R13: ffffc90003a27d58 R14: 0000000000000001 R15: 0000000000000001
FS: 0000000000000000(0000) GS:ffff8880d6579000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fd47fb30068 CR3: 000000003585a000 CR4: 0000000000352ef0
Call Trace:
<TASK>
pte_unmap include/linux/pgtable.h:117 [inline]
finish_fault+0x8ed/0x1400 mm/memory.c:5763
do_cow_fault mm/memory.c:5935 [inline]
do_fault+0xff2/0x1750 mm/memory.c:6029
do_pte_missing mm/memory.c:4550 [inline]
handle_pte_fault mm/memory.c:6411 [inline]
__handle_mm_fault+0x187d/0x2a00 mm/memory.c:6549
handle_mm_fault+0x36d/0xa20 mm/memory.c:6718
do_user_addr_fault+0x5a3/0x12f0 arch/x86/mm/fault.c:1334
handle_page_fault arch/x86/mm/fault.c:1474 [inline]
exc_page_fault+0x6f/0xd0 arch/x86/mm/fault.c:1527
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618
RIP: 0033:0x7fd47fe2aff2
Code: 0f 60 c0 66 0f 61 c0 66 0f 70 c0 00 48 83 fa 10 72 76 48 83 fa 20 77 12 0f 11 44 17 f0 0f 11 07 c3 0f 11 47 e0 0f 11 47 f0 c3 <0f> 11 07 0f 11 47 10 48 01 d7 48 83 fa 40 76 e7 0f 11 40 20 0f 11
RSP: 002b:00007ffcb5d4bcd8 EFLAGS: 00010206
RAX: 00007fd47fb30068 RBX: 0000000000000004 RCX: 00007fd47fb326d0
RDX: 0000000000000f98 RSI: 0000000000000000 RDI: 00007fd47fb30068
RBP: 00007ffcb5d4c0a0 R08: 00007fd47fb30068 R09: 0000000000000003
R10: 0000000000000812 R11: 00007ffcb5d4c188 R12: 00007ffcb5d4bd88
R13: 00007fd47fdffab0 R14: 00007ffcb5d4c140 R15: 00007fd47fb31000
</TASK>


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