[syzbot] [bcachefs?] INFO: task hung in __bch2_fs_stop

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    83a7eefedc9b Linux 6.10-rc3
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=164ac82e980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=c79815c08cc14227
dashboard link: https://syzkaller.appspot.com/bug?extid=6d3e28b33490b3085412
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1653cfba980000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1316587a980000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/b45273014a8f/disk-83a7eefe.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/94cd5708292e/vmlinux-83a7eefe.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a89698812e8b/bzImage-83a7eefe.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/3ef828450a9b/mount_0.gz

The issue was bisected to:

commit 267b801fda10b70eca4001a819fcac07f023df6b
Author: Kent Overstreet <kent.overstreet@xxxxxxxxx>
Date:   Mon Dec 4 18:45:33 2023 +0000

    bcachefs: BCH_IOCTL_FSCK_ONLINE

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=15166a54980000
final oops:     https://syzkaller.appspot.com/x/report.txt?x=17166a54980000
console output: https://syzkaller.appspot.com/x/log.txt?x=13166a54980000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+6d3e28b33490b3085412@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 267b801fda10 ("bcachefs: BCH_IOCTL_FSCK_ONLINE")

INFO: task syz-executor427:5081 blocked for more than 143 seconds.
      Not tainted 6.10.0-rc3-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor427 state:D stack:22048 pid:5081  tgid:5081  ppid:5078   flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5408 [inline]
 __schedule+0x1796/0x49d0 kernel/sched/core.c:6745
 __schedule_loop kernel/sched/core.c:6822 [inline]
 schedule+0x14b/0x320 kernel/sched/core.c:6837
 __bch2_fs_stop+0x35b/0x540 fs/bcachefs/super.c:628
 generic_shutdown_super+0x136/0x2d0 fs/super.c:642
 bch2_kill_sb+0x41/0x50 fs/bcachefs/fs.c:2034
 deactivate_locked_super+0xc4/0x130 fs/super.c:473
 cleanup_mnt+0x41f/0x4b0 fs/namespace.c:1267
 task_work_run+0x24f/0x310 kernel/task_work.c:180
 ptrace_notify+0x2d2/0x380 kernel/signal.c:2402
 ptrace_report_syscall include/linux/ptrace.h:415 [inline]
 ptrace_report_syscall_exit include/linux/ptrace.h:477 [inline]
 syscall_exit_work+0xc6/0x190 kernel/entry/common.c:173
 syscall_exit_to_user_mode_prepare kernel/entry/common.c:200 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:205 [inline]
 syscall_exit_to_user_mode+0x273/0x370 kernel/entry/common.c:218
 do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f70db0df3c7
RSP: 002b:00007ffd58b093d8 EFLAGS: 00000206 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00007f70db0df3c7
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffd58b09490
RBP: 00007ffd58b09490 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000206 R12: 00007ffd58b0a4f0
R13: 000055558a2c86c0 R14: 0000000000000019 R15: 431bde82d7b634db
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/30:
 #0: ffffffff8e333fa0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:329 [inline]
 #0: ffffffff8e333fa0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:781 [inline]
 #0: ffffffff8e333fa0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x2a0 kernel/locking/lockdep.c:6614
2 locks held by kworker/u8:7/1105:
1 lock held by klogd/4526:
2 locks held by getty/4836:
 #0: ffff88802f6310a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc90002f162f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x6b5/0x1e10 drivers/tty/n_tty.c:2201
1 lock held by syz-executor427/5081:
 #0: ffff88807e8180e0 (&type->s_umount_key#44){+.+.}-{3:3}, at: __super_lock fs/super.c:56 [inline]
 #0: ffff88807e8180e0 (&type->s_umount_key#44){+.+.}-{3:3}, at: __super_lock_excl fs/super.c:71 [inline]
 #0: ffff88807e8180e0 (&type->s_umount_key#44){+.+.}-{3:3}, at: deactivate_super+0xb5/0xf0 fs/super.c:505

=============================================

NMI backtrace for cpu 1
CPU: 1 PID: 30 Comm: khungtaskd Not tainted 6.10.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
 nmi_cpu_backtrace+0x49c/0x4d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x198/0x320 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:162 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:223 [inline]
 watchdog+0xfde/0x1020 kernel/hung_task.c:379
 kthread+0x2f0/0x390 kernel/kthread.c:389
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 1105 Comm: kworker/u8:7 Not tainted 6.10.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
Workqueue: events_unbound toggle_allocation_gate
RIP: 0010:PagePoisoned include/linux/page-flags.h:296 [inline]
RIP: 0010:PageReserved include/linux/page-flags.h:536 [inline]
RIP: 0010:__text_poke+0x187/0xd30 arch/x86/kernel/alternative.c:1864
Code: 00 00 00 00 00 ea ff ff 4c 89 ff e8 13 33 0d 00 49 89 c4 49 c1 ec 06 49 83 e4 c0 49 01 dc 4c 89 e3 48 c1 eb 03 42 80 3c 2b 00 <74> 08 4c 89 e7 e8 ff 88 c3 00 4d 8b 34 24 48 c7 c7 ff ff ff ff 4c
RSP: 0018:ffffc900043f7740 EFLAGS: 00000246
RAX: 0000000001ed289c RBX: 1ffffd400000f690 RCX: ffff888022338000
RDX: 0000000000000000 RSI: 0000000001ed289c RDI: 000000001fffffff
RBP: ffffc900043f7910 R08: ffffffff81424c05 R09: 1ffffffff1f583d5
R10: dffffc0000000000 R11: fffffbfff1f583d6 R12: ffffea000007b480
R13: dffffc0000000000 R14: 0000000000000001 R15: ffffffff81ed289c
FS:  0000000000000000(0000) GS:ffff8880b9400000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005622c0cea600 CR3: 000000000e132000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <NMI>
 </NMI>
 <TASK>
 text_poke arch/x86/kernel/alternative.c:1968 [inline]
 text_poke_bp_batch+0x8cd/0xb30 arch/x86/kernel/alternative.c:2357
 text_poke_flush arch/x86/kernel/alternative.c:2470 [inline]
 text_poke_finish+0x30/0x50 arch/x86/kernel/alternative.c:2477
 arch_jump_label_transform_apply+0x1c/0x30 arch/x86/kernel/jump_label.c:146
 static_key_enable_cpuslocked+0x136/0x260 kernel/jump_label.c:205
 static_key_enable+0x1a/0x20 kernel/jump_label.c:218
 toggle_allocation_gate+0xb5/0x250 mm/kfence/core.c:826
 process_one_work kernel/workqueue.c:3231 [inline]
 process_scheduled_works+0xa2c/0x1830 kernel/workqueue.c:3312
 worker_thread+0x86d/0xd70 kernel/workqueue.c:3393
 kthread+0x2f0/0x390 kernel/kthread.c:389
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 1.167 msecs


---
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