INFO: task rcu_tasks_kthre:11 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:rcu_tasks_kthre state:D stack:27200 pid:   11 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11c3/0x4350 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 schedule_timeout+0xbd/0x2d0 kernel/time/timer.c:2093
 do_wait_for_common+0x295/0x460 kernel/sched/completion.c:85
 __wait_for_common kernel/sched/completion.c:106 [inline]
 wait_for_common kernel/sched/completion.c:117 [inline]
 wait_for_completion+0x48/0x60 kernel/sched/completion.c:138
 __synchronize_srcu+0x2b5/0x350 kernel/rcu/srcutree.c:930
 rcu_tasks_wait_gp+0x43b/0x8e0 kernel/rcu/tasks.h:327
 rcu_tasks_kthread+0x2c1/0x640 kernel/rcu/tasks.h:226
 kthread+0x42e/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/27:
 #0: ffffffff8d11efa0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
3 locks held by kworker/u4:2/154:
3 locks held by kworker/0:2/1111:
2 locks held by getty/3939:
 #0: ffff88802db12098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
 #1: ffffc90002cf62e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x594/0x1a50 drivers/tty/n_tty.c:2158
3 locks held by syz.2.4820/19514:
3 locks held by syz.2.4838/19565:
2 locks held by syz.5.4849/19598:
2 locks held by syz.2.4853/19623:
3 locks held by syz.4.4866/19662:
2 locks held by syz.5.4871/19675:
2 locks held by syz.4.4875/19684:
 #0: ffffffff8d16c808 (event_mutex){+.+.}-{3:3}, at: perf_trace_destroy+0x2a/0x140 kernel/trace/trace_event_perf.c:239
 #1: ffffffff8d123a28 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:290 [inline]
 #1: ffffffff8d123a28 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x2d1/0x750 kernel/rcu/tree_exp.h:845
3 locks held by syz.0.4881/19695:
2 locks held by syz.2.4880/19698:
 #0: ffffffff8e24d5c8 (rtnl_mutex){+.+.}-{3:3}, at: tun_detach drivers/net/tun.c:699 [inline]
 #0: ffffffff8e24d5c8 (rtnl_mutex){+.+.}-{3:3}, at: tun_chr_close+0x3d/0x1b0 drivers/net/tun.c:3454
 #1: ffffffff8d123a28 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:322 [inline]
 #1: ffffffff8d123a28 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x3a5/0x750 kernel/rcu/tree_exp.h:845

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

NMI backtrace for cpu 0
CPU: 0 PID: 27 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x3a2/0x3d0 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:212 [inline]
 watchdog+0xe1b/0xe60 kernel/hung_task.c:369
 kthread+0x42e/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 19695 Comm: syz.0.4881 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
RIP: 0010:unwind_next_frame+0x1028/0x1cf0 arch/x86/kernel/unwind_orc.c:592
Code: 7c cc 4c 89 ff 48 89 14 24 48 89 74 24 20 e8 ff 39 89 00 48 8b 74 24 20 48 8b 14 24 eb b0 4d 8d 7c 24 02 49 83 c4 03 4c 89 f8 <48> c1 e8 03 0f b6 04 28 84 c0 0f 85 16 0b 00 00 4c 89 e0 48 c1 e8
RSP: 0018:ffffc90003bde3d0 EFLAGS: 00000282
RAX: ffffffff8eeddf3c RBX: ffffc90003bde468 RCX: 0000000000000000
RDX: 0000000000000010 RSI: 0000000000000001 RDI: ffffc90003bde4c8
RBP: dffffc0000000000 R08: ffffc90003bdef90 R09: ffffc90003bde4b8
R10: dffffc0000000000 R11: fffff5200077bc99 R12: ffffffff8eeddf3d
R13: 1ffffffff1ddbbe7 R14: ffffc90003bde49d R15: ffffffff8eeddf3c
FS:  00007fa5ce93b6c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f76e8eb0c40 CR3: 00000000608e4000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <TASK>
 arch_stack_walk+0x10c/0x140 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0xa6/0xf0 kernel/stacktrace.c:122
 save_stack+0x121/0x230 mm/page_owner.c:119
 __set_page_owner+0x41/0x2d0 mm/page_owner.c:181
 prep_new_page mm/page_alloc.c:2426 [inline]
 get_page_from_freelist+0x24f6/0x2670 mm/page_alloc.c:4192
 __alloc_pages+0x1ee/0x480 mm/page_alloc.c:5501
 alloc_pages_vma+0x2bc/0x790 mm/mempolicy.c:2146
 shmem_alloc_page mm/shmem.c:1586 [inline]
 shmem_alloc_and_acct_page+0x47f/0xbe0 mm/shmem.c:1611
 shmem_getpage_gfp+0x14be/0x2c10 mm/shmem.c:1906
 shmem_getpage mm/shmem.c:151 [inline]
 shmem_write_begin+0xcd/0x1a0 mm/shmem.c:2474
 generic_perform_write+0x2b6/0x550 mm/filemap.c:3785
 __generic_file_write_iter+0x261/0x4e0 mm/filemap.c:3912
 generic_file_write_iter+0xa6/0x1b0 mm/filemap.c:3944
 __kernel_write+0x522/0x980 fs/read_write.c:539
 __dump_emit+0x258/0x380 fs/coredump.c:943
 dump_user_range+0x84/0x340 fs/coredump.c:1017
 elf_core_dump+0x2fe0/0x3530 fs/binfmt_elf.c:2285
 do_coredump+0x14e8/0x2a40 fs/coredump.c:894
 get_signal+0x531/0x12e0 kernel/signal.c:2899
 arch_do_signal_or_restart+0xe6/0x12a0 arch/x86/kernel/signal.c:867
 handle_signal_work kernel/entry/common.c:157 [inline]
 exit_to_user_mode_loop+0x9e/0x130 kernel/entry/common.c:181
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:217
 irqentry_exit_to_user_mode+0x5/0x30 kernel/entry/common.c:323
 exc_general_protection+0x1e4/0x270 arch/x86/kernel/traps.c:562
 asm_exc_general_protection+0x22/0x30 arch/x86/include/asm/idtentry.h:600
RIP: 0033:0x7fa5d06e3561
Code: 00 00 00 00 0f 1f 44 00 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 <c3> 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f
RSP: 002b:0000200000000020 EFLAGS: 00010217
RAX: 0000000000000000 RBX: 00007fa5d096afa0 RCX: 00007fa5d06e3559
RDX: 00002000000000c0 RSI: 0000200000000020 RDI: 0000000000008000
RBP: 00007fa5d077a8b0 R08: 0000200000000140 R09: 0000200000000140
R10: 0000200000000100 R11: 0000000000000206 R12: 0000000000000000
R13: 00007fa5d096b038 R14: 00007fa5d096afa0 R15: 00007ffc40d0e348
 </TASK>