INFO: task kworker/u8:8:3574 blocked for more than 143 seconds. Not tainted 6.13.0-rc5-syzkaller-00012-g0bc21e701a6f #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:kworker/u8:8 state:D stack:20464 pid:3574 tgid:3574 ppid:2 flags:0x00004000 Workqueue: writeback wb_workfn (flush-7:4) Call Trace: <TASK> context_switch kernel/sched/core.c:5369 [inline] __schedule+0x17fb/0x4be0 kernel/sched/core.c:6756 __schedule_loop kernel/sched/core.c:6833 [inline] schedule+0x14b/0x320 kernel/sched/core.c:6848 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6905 __mutex_lock_common kernel/locking/mutex.c:665 [inline] __mutex_lock+0x7e7/0xee0 kernel/locking/mutex.c:735 exfat_write_inode+0xe5/0x1a0 fs/exfat/inode.c:108 write_inode fs/fs-writeback.c:1525 [inline] __writeback_single_inode+0x708/0x10d0 fs/fs-writeback.c:1745 writeback_sb_inodes+0x820/0x1360 fs/fs-writeback.c:1976 __writeback_inodes_wb+0x11b/0x260 fs/fs-writeback.c:2047 wb_writeback+0x427/0xb80 fs/fs-writeback.c:2158 wb_check_background_flush fs/fs-writeback.c:2228 [inline] wb_do_writeback fs/fs-writeback.c:2316 [inline] wb_workfn+0xc4b/0x1080 fs/fs-writeback.c:2343 process_one_work kernel/workqueue.c:3229 [inline] process_scheduled_works+0xa66/0x1840 kernel/workqueue.c:3310 worker_thread+0x870/0xd30 kernel/workqueue.c:3391 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> Showing all locks held in the system: 1 lock held by pool_workqueue_/3: #0: ffffffff8e93cff8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock kernel/rcu/tree_exp.h:297 [inline] ffffffff8e93cff8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x381/0x830 kernel/rcu/tree_exp.h:976 1 lock held by khungtaskd/30: #0: ffffffff8e937ae0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline] #0: ffffffff8e937ae0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #0: ffffffff8e937ae0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x55/0x2a0 kernel/locking/lockdep.c:6744 2 locks held by kworker/u8:4/63: #0: ffff88814769c148 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3204 [inline] #0: ffff88814769c148 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_scheduled_works+0x93b/0x1840 kernel/workqueue.c:3310 #1: ffffc90001547d00 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3205 [inline] #1: ffffc90001547d00 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_scheduled_works+0x976/0x1840 kernel/workqueue.c:3310 3 locks held by kworker/u8:5/1055: #0: ffff88814d636948 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3204 [inline] #0: ffff88814d636948 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_scheduled_works+0x93b/0x1840 kernel/workqueue.c:3310 #1: ffffc9000476fd00 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3205 [inline] #1: ffffc9000476fd00 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x976/0x1840 kernel/workqueue.c:3310 #2: ffffffff8fca0808 (rtnl_mutex){+.+.}-{4:4}, at: addrconf_dad_work+0xd0/0x16f0 net/ipv6/addrconf.c:4215 4 locks held by kworker/u8:8/3574: #0: ffff88801e2ce148 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3204 [inline] #0: ffff88801e2ce148 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x93b/0x1840 kernel/workqueue.c:3310 #1: ffffc9000d6bfd00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3205 [inline] #1: ffffc9000d6bfd00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x976/0x1840 kernel/workqueue.c:3310 #2: ffff8880300b60e0 (&type->s_umount_key#53){++++}-{4:4}, at: super_trylock_shared+0x22/0xf0 fs/super.c:562 #3: ffff8880300b40e8 (&sbi->s_lock){+.+.}-{4:4}, at: exfat_write_inode+0xe5/0x1a0 fs/exfat/inode.c:108 2 locks held by getty/5575: #0: ffff888031ad30a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243 #1: ffffc9000332b2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x6a6/0x1e00 drivers/tty/n_tty.c:2211 3 locks held by kworker/0:5/5943: 3 locks held by syz.4.22/6099: 3 locks held by syz-executor/7424: #0: ffffffff8fca0808 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:79 [inline] #0: ffffffff8fca0808 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_nets_lock net/core/rtnetlink.c:326 [inline] #0: ffffffff8fca0808 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0xce2/0x2210 net/core/rtnetlink.c:4011 #1: ffff88805cbf94e8 (&wg->device_update_lock){+.+.}-{4:4}, at: wg_open+0x22d/0x420 drivers/net/wireguard/device.c:50 #2: ffffffff8e93cff8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock kernel/rcu/tree_exp.h:329 [inline] #2: ffffffff8e93cff8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x451/0x830 kernel/rcu/tree_exp.h:976 2 locks held by syz.7.191/7651: #0: ffff88802973fb38 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x254/0x320 fs/file.c:1191 #1: ffff888028cd2420 (sb_writers#21){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2964 [inline] #1: ffff888028cd2420 (sb_writers#21){.+.+}-{0:0}, at: vfs_write+0x225/0xd30 fs/read_write.c:675 2 locks held by sed/7698: ============================================= NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 30 Comm: khungtaskd Not tainted 6.13.0-rc5-syzkaller-00012-g0bc21e701a6f #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 Call Trace: <TASK> __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120 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:234 [inline] watchdog+0xff6/0x1040 kernel/hung_task.c:397 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 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 974 Comm: kworker/1:2 Not tainted 6.13.0-rc5-syzkaller-00012-g0bc21e701a6f #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 Workqueue: mld mld_dad_work RIP: 0010:__bfs_next kernel/locking/lockdep.c:1698 [inline] RIP: 0010:__bfs kernel/locking/lockdep.c:1748 [inline] RIP: 0010:__bfs_backwards kernel/locking/lockdep.c:1856 [inline] RIP: 0010:check_irq_usage kernel/locking/lockdep.c:2827 [inline] RIP: 0010:check_prev_add kernel/locking/lockdep.c:3165 [inline] RIP: 0010:check_prevs_add kernel/locking/lockdep.c:3280 [inline] RIP: 0010:validate_chain+0x1cc4/0x5920 kernel/locking/lockdep.c:3904 Code: 7d 00 48 8d bc 24 20 01 00 00 48 89 fb 48 c1 eb 03 42 80 3c 23 00 74 05 e8 29 ce 87 00 4c 89 bc 24 20 01 00 00 4d 39 f7 74 21 <42> 80 3c 23 00 74 0d 48 8d bc 24 20 01 00 00 e8 18 cd 87 00 4c 8b RSP: 0018:ffffc90004426f00 EFLAGS: 00000006 RAX: 1ffffffff2da2893 RBX: 1ffff92000884e04 RCX: dffffc0000000000 RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffc90004427020 RBP: ffffc90004427200 R08: ffffffff9427188f R09: 1ffffffff284e311 R10: dffffc0000000000 R11: fffffbfff284e312 R12: dffffc0000000000 R13: ffffffff96d14498 R14: ffffffff93c01ed8 R15: ffffffff96d193c8 FS: 0000000000000000(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f552fa4ad58 CR3: 0000000025390000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <NMI> </NMI> <TASK> __lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5226 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849 do_write_seqcount_begin_nested include/linux/seqlock.h:454 [inline] do_write_seqcount_begin include/linux/seqlock.h:480 [inline] psi_account_irqtime+0x34a/0x830 kernel/sched/psi.c:1026 __schedule+0x948/0x4be0 kernel/sched/core.c:6750 preempt_schedule_common+0x84/0xd0 kernel/sched/core.c:6935 preempt_schedule+0xe1/0xf0 kernel/sched/core.c:6959 preempt_schedule_thunk+0x1a/0x30 arch/x86/entry/thunk.S:12 __local_bh_enable_ip+0x179/0x200 kernel/softirq.c:396 ipv6_get_lladdr+0x295/0x3d0 net/ipv6/addrconf.c:1936 mld_newpack+0x337/0xaf0 net/ipv6/mcast.c:1755 add_grhead net/ipv6/mcast.c:1850 [inline] add_grec+0x1492/0x19a0 net/ipv6/mcast.c:1988 mld_send_initial_cr+0x228/0x4b0 net/ipv6/mcast.c:2234 mld_dad_work+0x44/0x500 net/ipv6/mcast.c:2260 process_one_work kernel/workqueue.c:3229 [inline] process_scheduled_works+0xa66/0x1840 kernel/workqueue.c:3310 worker_thread+0x870/0xd30 kernel/workqueue.c:3391 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>