[v6.1] WARNING in unlock_mount (4)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: ad16b162f21d Linux 6.1.172
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=114cfbce580000
kernel config: https://syzkaller.appspot.com/x/.config?x=b1adc0bfde2d8a4a
dashboard link: https://syzkaller.appspot.com/bug?extid=8dfbc67d7d4f696c7ed7
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
userspace arch: arm64

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/01975838d01a/disk-ad16b162.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/025b6eac2853/vmlinux-ad16b162.xz
kernel image: https://storage.googleapis.com/syzbot-assets/4defc266eb64/Image-ad16b162.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8dfbc6...@syzkaller.appspotmail.com

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DEBUG_RWSEMS_WARN_ON((rwsem_owner(sem) != current) && !rwsem_test_oflags(sem, RWSEM_NONSPINNABLE)): count = 0x0, magic = 0xffff0000f526f318, owner = 0x0, curr 0xffff0000db51d340, list empty
WARNING: CPU: 1 PID: 4821 at kernel/locking/rwsem.c:1372 __up_write kernel/locking/rwsem.c:1371 [inline]
WARNING: CPU: 1 PID: 4821 at kernel/locking/rwsem.c:1372 up_write+0x494/0x5bc kernel/locking/rwsem.c:1626
Modules linked in:
CPU: 1 PID: 4821 Comm: syz.4.108 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
pstate: 62400005 (nZCv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=--)
pc : __up_write kernel/locking/rwsem.c:1371 [inline]
pc : up_write+0x494/0x5bc kernel/locking/rwsem.c:1626
lr : __up_write kernel/locking/rwsem.c:1371 [inline]
lr : up_write+0x494/0x5bc kernel/locking/rwsem.c:1626
sp : ffff800021117ab0
x29: ffff800021117ac0 x28: 1fffe0001b29c0bc x27: dfff800000000000
x26: dfff800000000000 x25: 1fffe0001ea4de70 x24: ffff0000f526f370
x23: 0000000000000000 x22: 0000000000000000 x21: ffff0000db51d340
x20: ffff0000f526f318 x19: ffff0000f526f318 x18: ffff800011b9bf60
x17: 1fffe00033eaa57e x16: ffff8000082d92bc x15: 0000000040000000
x14: 0000000000000001 x13: 1fffe00033eacc30 x12: 0000000000ff0100
x11: ff0080000a8df3f0 x10: 0000000000000003 x9 : a5c15130d8108100
x8 : a5c15130d8108100 x7 : ffff800008257984 x6 : 0000000000000000
x5 : 0000000000000080 x4 : 0000000000000001 x3 : 0000000000000000
x2 : ffff800021117640 x1 : ffff800011b9da80 x0 : ffff80018a3dd000
Call trace:
__up_write kernel/locking/rwsem.c:1371 [inline]
up_write+0x494/0x5bc kernel/locking/rwsem.c:1626
inode_unlock include/linux/fs.h:763 [inline]
unlock_mount+0x1d4/0x240 fs/namespace.c:2337
do_new_mount_fc fs/namespace.c:3021 [inline]
do_new_mount+0x658/0x810 fs/namespace.c:3080
path_mount+0x5bc/0xe80 fs/namespace.c:3408
do_mount fs/namespace.c:3421 [inline]
__do_sys_mount fs/namespace.c:3629 [inline]
__se_sys_mount fs/namespace.c:3606 [inline]
__arm64_sys_mount+0x49c/0x59c fs/namespace.c:3606
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2b4 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
do_el0_svc+0x58/0x130 arch/arm64/kernel/syscall.c:204
el0_svc+0x58/0x128 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585
irq event stamp: 584
hardirqs last enabled at (583): [<ffff800008257a18>] raw_spin_rq_unlock_irq kernel/sched/sched.h:1374 [inline]
hardirqs last enabled at (583): [<ffff800008257a18>] finish_lock_switch+0xb0/0x1c4 kernel/sched/core.c:5004
hardirqs last disabled at (584): [<ffff800011a389f4>] el1_dbg+0x24/0x80 arch/arm64/kernel/entry-common.c:405
softirqs last enabled at (576): [<ffff8000081ac394>] softirq_handle_end kernel/softirq.c:439 [inline]
softirqs last enabled at (576): [<ffff8000081ac394>] handle_softirqs+0xaec/0xc60 kernel/softirq.c:624
softirqs last disabled at (565): [<ffff800008020164>] __do_softirq+0x14/0x20 kernel/softirq.c:630
---[ end trace 0000000000000000 ]---


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