syzbot

INFO: task bch-copygc/loop:5829 blocked for more than 143 seconds.
      Not tainted 6.14.0-syzkaller-03576-g1e1ba8d23dae #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:bch-copygc/loop state:D stack:19760 pid:5829  tgid:5829  ppid:2      task_flags:0x240040 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5366 [inline]
 __schedule+0x1ac3/0x5090 kernel/sched/core.c:6747
 __schedule_loop kernel/sched/core.c:6824 [inline]
 schedule+0x163/0x360 kernel/sched/core.c:6839
 __closure_sync+0x25d/0x300 lib/closure.c:146
 bch2_wait_on_allocator fs/bcachefs/alloc_foreground.h:237 [inline]
 __bch2_write+0x538f/0x5aa0 fs/bcachefs/io_write.c:1530
 bch2_write+0x867/0x1660 fs/bcachefs/io_write.c:1659
 closure_queue include/linux/closure.h:270 [inline]
 closure_call include/linux/closure.h:432 [inline]
 bch2_data_update_read_done+0x238/0x330 fs/bcachefs/data_update.c:439
 move_write fs/bcachefs/move.c:135 [inline]
 bch2_moving_ctxt_do_pending_writes+0x44e/0x8d0 fs/bcachefs/move.c:166
 bch2_move_ratelimit+0x8f6/0x13a0 fs/bcachefs/move.c:512
 bch2_evacuate_bucket+0x10c9/0x32f0 fs/bcachefs/move.c:747
 bch2_copygc+0x4174/0x4fb0 fs/bcachefs/movinggc.c:240
 bch2_copygc_thread+0x6f1/0xba0 fs/bcachefs/movinggc.c:383
 kthread+0x7a9/0x920 kernel/kthread.c:464
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/31:
 #0: ffffffff8eb3a860 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8eb3a860 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #0: ffffffff8eb3a860 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x30/0x180 kernel/locking/lockdep.c:6761
2 locks held by getty/5587:
 #0: ffff88814d8e90a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc9000333b2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x53d/0x16b0 drivers/tty/n_tty.c:2211
2 locks held by syz-executor152/6535:

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

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 31 Comm: khungtaskd Not tainted 6.14.0-syzkaller-03576-g1e1ba8d23dae #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x4ab/0x4e0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x198/0x320 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:158 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:236 [inline]
 watchdog+0x1058/0x10a0 kernel/hung_task.c:399
 kthread+0x7a9/0x920 kernel/kthread.c:464
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 5813 Comm: sshd Not tainted 6.14.0-syzkaller-03576-g1e1ba8d23dae #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
RIP: 0010:virtqueue_add_split drivers/virtio/virtio_ring.c:-1 [inline]
RIP: 0010:virtqueue_add+0xfbd/0x4820 drivers/virtio/virtio_ring.c:2282
Code: 07 80 c1 03 38 c1 0f 8c 4f ff ff ff e8 ac 2c bc fc 48 8b 54 24 10 e9 40 ff ff ff e8 2d 8e 56 fc e9 e6 12 00 00 e8 23 8e 56 fc <48> 8b 44 24 08 48 8d 78 60 48 89 f8 48 c1 e8 03 48 b9 00 00 00 00
RSP: 0018:ffffc90003e3e7a0 EFLAGS: 00000293
RAX: ffffffff856ccdf8 RBX: 0000000000000003 RCX: ffff88807b29bc00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90003e3ea18 R08: ffffffff856ccde5 R09: ffff888033aa8af0
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: ffff8880256c6000 R14: 0000000000001000 R15: 0000000000000000
FS:  00007f5a5b988800(0000) GS:ffff888125259000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fa6201a1000 CR3: 0000000077b2a000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <NMI>
 </NMI>
 <TASK>
 virtqueue_add_outbuf+0xc5/0x110 drivers/virtio/virtio_ring.c:2339
 virtnet_add_outbuf drivers/net/virtio_net.c:567 [inline]
 xmit_skb drivers/net/virtio_net.c:3241 [inline]
 start_xmit+0x1161/0x2500 drivers/net/virtio_net.c:3270
 __netdev_start_xmit include/linux/netdevice.h:5151 [inline]
 netdev_start_xmit include/linux/netdevice.h:5160 [inline]
 xmit_one net/core/dev.c:3800 [inline]
 dev_hard_start_xmit+0x27a/0x7d0 net/core/dev.c:3816
 sch_direct_xmit+0x2b2/0x600 net/sched/sch_generic.c:343
 __dev_xmit_skb net/core/dev.c:4042 [inline]
 __dev_queue_xmit+0x1a9c/0x3f60 net/core/dev.c:4618
 dev_queue_xmit include/linux/netdevice.h:3313 [inline]
 neigh_hh_output include/net/neighbour.h:523 [inline]
 neigh_output include/net/neighbour.h:537 [inline]
 ip_finish_output2+0xcd5/0x12e0 net/ipv4/ip_output.c:236
 ip_local_out net/ipv4/ip_output.c:130 [inline]
 __ip_queue_xmit+0x1042/0x1960 net/ipv4/ip_output.c:528
 __tcp_transmit_skb+0x23d0/0x3a80 net/ipv4/tcp_output.c:1471
 tcp_transmit_skb net/ipv4/tcp_output.c:1489 [inline]
 tcp_write_xmit+0x16e6/0x66d0 net/ipv4/tcp_output.c:2832
 __tcp_push_pending_frames+0x9b/0x360 net/ipv4/tcp_output.c:3015
 tcp_sendmsg_locked+0x47e3/0x5340 net/ipv4/tcp.c:1326
 tcp_sendmsg+0x30/0x50 net/ipv4/tcp.c:1358
 sock_sendmsg_nosec net/socket.c:718 [inline]
 __sock_sendmsg+0x1a6/0x270 net/socket.c:733
 sock_write_iter+0x2d9/0x3f0 net/socket.c:1137
 new_sync_write fs/read_write.c:591 [inline]
 vfs_write+0x70f/0xd10 fs/read_write.c:684
 ksys_write+0x19d/0x2d0 fs/read_write.c:736
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f5a5b516bf2
Code: 89 c7 48 89 44 24 08 e8 7b 34 fa ff 48 8b 44 24 08 48 83 c4 28 c3 c3 64 8b 04 25 18 00 00 00 85 c0 75 20 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 76 6f 48 8b 15 07 a2 0d 00 f7 d8 64 89 02 48 83
RSP: 002b:00007ffd4f977ef8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 000000000000003c RCX: 00007f5a5b516bf2
RDX: 000000000000003c RSI: 0000563a61b47990 RDI: 0000000000000004
RBP: 0000563a61b55250 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000563a2e2deaa4
R13: 000000000000011f R14: 0000563a2e2df3e8 R15: 00007ffd4f977f68
 </TASK>
INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 1.628 msecs