[v5.15] BUG: soft lockup in chrdev_open

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 12952a23a5da Linux 5.15.137
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=13589e37680000
kernel config: https://syzkaller.appspot.com/x/.config?x=d5d31a3160e35771
dashboard link: https://syzkaller.appspot.com/bug?extid=5c6a914efbe6ca9078de
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: arm64

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/a52e721f848f/disk-12952a23.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f568d3b2b0c4/vmlinux-12952a23.xz
kernel image: https://storage.googleapis.com/syzbot-assets/5c8641a162ac/Image-12952a23.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+5c6a91...@syzkaller.appspotmail.com

watchdog: BUG: soft lockup - CPU#0 stuck for 29s! [syz-executor.2:9030]
Modules linked in:
irq event stamp: 7192
hardirqs last enabled at (7191): [<ffff800011a46af8>] __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:160 [inline]
hardirqs last enabled at (7191): [<ffff800011a46af8>] _raw_spin_unlock_irqrestore+0xac/0x158 kernel/locking/spinlock.c:194
hardirqs last disabled at (7192): [<ffff80001196f560>] enter_el1_irq_or_nmi+0x10/0x1c arch/arm64/kernel/entry-common.c:227
softirqs last enabled at (7166): [<ffff800008020ccc>] softirq_handle_end kernel/softirq.c:401 [inline]
softirqs last enabled at (7166): [<ffff800008020ccc>] __do_softirq+0xb5c/0xe20 kernel/softirq.c:587
softirqs last disabled at (7161): [<ffff8000081b5750>] do_softirq_own_stack include/asm-generic/softirq_stack.h:10 [inline]
softirqs last disabled at (7161): [<ffff8000081b5750>] invoke_softirq kernel/softirq.c:439 [inline]
softirqs last disabled at (7161): [<ffff8000081b5750>] __irq_exit_rcu+0x28c/0x534 kernel/softirq.c:637
CPU: 0 PID: 9030 Comm: syz-executor.2 Not tainted 5.15.137-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023
pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline]
pc : _raw_spin_unlock_irqrestore+0xbc/0x158 kernel/locking/spinlock.c:194
lr : __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:160 [inline]
lr : _raw_spin_unlock_irqrestore+0xac/0x158 kernel/locking/spinlock.c:194
sp : ffff80001ec77190
x29: ffff80001ec771a0 x28: 1ffff00003d8ee4c x27: 1ffff00003d8ee4d
x26: dfff800000000000 x25: 0000000000000003 x24: 0000000000000000
x23: ffff0000ca5d00c0 x22: ffff80000ab45a5c x21: ffff0000c0e9c160
x20: ffff0000c0e9c148 x19: 0000000000000000 x18: 1fffe000368fe78e
x17: 1fffe000368fe78e x16: ffff8000082eb4c0 x15: ffff8000149becc0
x14: 1ffff0000292406a x13: ffffffffffffffff x12: 0000000000040000
x11: 000000000003ffff x10: 0000000000000003 x9 : 0000000000000080
x8 : 00000000000000c0 x7 : 0000000000000000 x6 : 0000000000000000
x5 : 0000000000000080 x4 : 0000000000000000 x3 : ffff800008045860
x2 : 0000000000000006 x1 : ffff800011acab40 x0 : ffff80019ff83000
Call trace:
arch_local_irq_restore arch/arm64/include/asm/irqflags.h:122 [inline]
__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:160 [inline]
_raw_spin_unlock_irqrestore+0xbc/0x158 kernel/locking/spinlock.c:194
spin_unlock_irqrestore include/linux/spinlock.h:418 [inline]
klist_next+0x1ec/0x2f4 lib/klist.c:401
class_dev_iter_next drivers/base/class.c:316 [inline]
class_find_device+0x17c/0x290 drivers/base/class.c:420
class_find_device_by_devt include/linux/device/class.h:167 [inline]
tty_get_device drivers/tty/tty_io.c:3108 [inline]
alloc_tty_struct+0x570/0x6bc drivers/tty/tty_io.c:3155
pty_common_install+0x154/0x684 drivers/tty/pty.c:379
pty_unix98_install+0x2c/0x3c drivers/tty/pty.c:721
tty_driver_install_tty drivers/tty/tty_io.c:1317 [inline]
tty_init_dev+0xb4/0x420 drivers/tty/tty_io.c:1431
ptmx_open+0xfc/0x2e0 drivers/tty/pty.c:824
chrdev_open+0x3e8/0x4fc fs/char_dev.c:414
do_dentry_open+0x780/0xed8 fs/open.c:826
vfs_open+0x7c/0x90 fs/open.c:956
do_open fs/namei.c:3538 [inline]
path_openat+0x1f28/0x26f0 fs/namei.c:3672
do_filp_open+0x1a8/0x3b4 fs/namei.c:3699
do_sys_openat2+0x128/0x3d8 fs/open.c:1211
do_sys_open fs/open.c:1227 [inline]
__do_sys_openat fs/open.c:1243 [inline]
__se_sys_openat fs/open.c:1238 [inline]
__arm64_sys_openat+0x1f0/0x240 fs/open.c:1238
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:608
el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626
el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584


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[syzbot]

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