INFO: task syz.5.805:8515 blocked for more than 143 seconds. Not tainted syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz.5.805 state:D stack:27064 pid:8515 tgid:8508 ppid:5858 task_flags:0x400040 flags:0x00004004 Call Trace: context_switch kernel/sched/core.c:5357 [inline] __schedule+0x1798/0x4cc0 kernel/sched/core.c:6961 __schedule_loop kernel/sched/core.c:7043 [inline] schedule+0x165/0x360 kernel/sched/core.c:7058 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7115 __mutex_lock_common kernel/locking/mutex.c:676 [inline] __mutex_lock+0x7e6/0x1350 kernel/locking/mutex.c:760 sync_bdevs+0x1ac/0x340 block/bdev.c:1288 ksys_sync+0xb9/0x150 fs/sync.c:105 __ia32_sys_sync+0xe/0x20 fs/sync.c:113 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f08d3d8ebe9 RSP: 002b:00007f08d4b72038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2 RAX: ffffffffffffffda RBX: 00007f08d3fb6090 RCX: 00007f08d3d8ebe9 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 00007f08d3fb6090 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f08d3fb6128 R14: 00007f08d3fb6090 R15: 00007ffefb999f78 Showing all locks held in the system: 1 lock held by khungtaskd/31: #0: ffffffff8e139ee0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #0: ffffffff8e139ee0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline] #0: ffffffff8e139ee0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775 2 locks held by getty/5614: #0: ffff88814d8430a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243 #1: ffffc900036c62f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x43e/0x1400 drivers/tty/n_tty.c:2222 4 locks held by kworker/u8:9/6019: 1 lock held by udevd/7719: #0: ffff888024ef9358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xe0/0xd30 block/bdev.c:945 1 lock held by udevd/7759: #0: ffff888024edb358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xe0/0xd30 block/bdev.c:945 1 lock held by syz.5.805/8515: #0: ffff888024edb358 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0x1ac/0x340 block/bdev.c:1288 1 lock held by syz.6.1132/9543: #0: ffff888024edb358 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0x1ac/0x340 block/bdev.c:1288 3 locks held by syz.4.1272/10023: 3 locks held by syz.4.1294/10097: 1 lock held by syz.7.1302/10129: 2 locks held by syz.1.1304/10119: #0: ffffffff8f538448 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline] #0: ffffffff8f538448 (rtnl_mutex){+.+.}-{4:4}, at: rtm_del_nexthop+0x354/0x5b0 net/ipv4/nexthop.c:3327 #1: ffffffff8e13f978 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock kernel/rcu/tree_exp.h:311 [inline] #1: ffffffff8e13f978 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x2f6/0x730 kernel/rcu/tree_exp.h:957 1 lock held by syz.1.1304/10121: #0: ffffffff8f538448 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline] #0: ffffffff8f538448 (rtnl_mutex){+.+.}-{4:4}, at: rtm_new_nexthop+0xe96/0x7eb0 net/ipv4/nexthop.c:3258 1 lock held by syz.1.1304/10123: #0: ffffffff8f538448 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline] #0: ffffffff8f538448 (rtnl_mutex){+.+.}-{4:4}, at: rtm_new_nexthop+0xe96/0x7eb0 net/ipv4/nexthop.c:3258 1 lock held by syz.1.1304/10125: #0: ffffffff8f538448 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline] #0: ffffffff8f538448 (rtnl_mutex){+.+.}-{4:4}, at: rtm_new_nexthop+0xe96/0x7eb0 net/ipv4/nexthop.c:3258 2 locks held by syz.0.1305/10122: #0: ffffffff8f59da70 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218 #1: ffffffff8f538448 (rtnl_mutex){+.+.}-{4:4}, at: nl80211_pre_doit+0x5f/0x930 net/wireless/nl80211.c:17363 1 lock held by syz.0.1305/10124: #0: ffffffff8f538448 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline] #0: ffffffff8f538448 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_nets_lock net/core/rtnetlink.c:341 [inline] #0: ffffffff8f538448 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x8db/0x1c70 net/core/rtnetlink.c:4056 ============================================= NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 31 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 Call Trace: dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120 nmi_cpu_backtrace+0x39e/0x3d0 lib/nmi_backtrace.c:113 nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:328 [inline] watchdog+0xf93/0xfe0 kernel/hung_task.c:491 kthread+0x711/0x8a0 kernel/kthread.c:463 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 10023 Comm: syz.4.1272 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 RIP: 0010:_compound_head include/linux/page-flags.h:286 [inline] RIP: 0010:put_page include/linux/mm.h:1424 [inline] RIP: 0010:dump_user_range+0x34f/0xc90 fs/coredump.c:1371 Code: 8b 44 24 10 4c 8d 70 08 4c 89 f0 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df 80 3c 08 00 74 08 4c 89 f7 e8 34 a9 cf ff 49 8b 1e <48> 89 de 48 83 e6 01 31 ff e8 f3 41 6c ff 48 89 d8 48 83 e0 01 0f RSP: 0018:ffffc9001e90edc0 EFLAGS: 00000246 RAX: 1ffffd4000321fd1 RBX: 0000000000000000 RCX: dffffc0000000000 RDX: 0000000000000000 RSI: 0000000000001000 RDI: 0000000000001000 RBP: ffffc9001e90ef50 R08: ffff88806b4215f7 R09: 1ffff1100d6842be R10: dffffc0000000000 R11: ffffed100d6842bf R12: 1ffff92003d21f7b R13: 0000000000000000 R14: ffffea000190fe88 R15: 00007f5a66cb7000 FS: 00007f5a686536c0(0000) GS:ffff888125d1b000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00005555925195c8 CR3: 0000000044715000 CR4: 0000000000350ef0 Call Trace: elf_core_dump+0x337b/0x3990 fs/binfmt_elf.c:2085 coredump_write+0x1169/0x1900 fs/coredump.c:1049 vfs_coredump+0x1daa/0x2a50 fs/coredump.c:1168 get_signal+0x1109/0x1340 kernel/signal.c:3019 arch_do_signal_or_restart+0x9a/0x750 arch/x86/kernel/signal.c:337 exit_to_user_mode_loop kernel/entry/common.c:40 [inline] exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline] irqentry_exit_to_user_mode+0x81/0x120 kernel/entry/common.c:73 exc_page_fault+0x9f/0xf0 arch/x86/mm/fault.c:1535 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623 RIP: 0033:0x7f5a6778ebf1 Code: 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 48 3d 01 f0 ff ff 73 01 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f RSP: 002b:00000000fffffe10 EFLAGS: 00010217 RAX: 0000000000000000 RBX: 00007f5a679b5fa0 RCX: 00007f5a6778ebe9 RDX: 0000000000000000 RSI: 00000000fffffe10 RDI: 0000000000000000 RBP: 00007f5a67811e19 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f5a679b6038 R14: 00007f5a679b5fa0 R15: 00007ffda3887df8