syzbot

INFO: task syz.3.1374:10407 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.3.1374      state:D stack:28296 pid:10407 tgid:10396 ppid:5828   task_flags:0x400040 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5325 [inline]
 __schedule+0x1798/0x4cc0 kernel/sched/core.c:6929
 __schedule_loop kernel/sched/core.c:7011 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:7026
 futex_hash_allocate+0x754/0xe60 kernel/futex/core.c:1829
 __do_sys_prctl kernel/sys.c:2869 [inline]
 __se_sys_prctl+0x9f1/0x1830 kernel/sys.c:2518
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f591e38efc9
RSP: 002b:00007f591f1a3038 EFLAGS: 00000246 ORIG_RAX: 000000000000009d
RAX: ffffffffffffffda RBX: 00007f591e5e6180 RCX: 00007f591e38efc9
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 000000000000004e
RBP: 00007f591e411f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f591e5e6218 R14: 00007f591e5e6180 R15: 00007ffee4b67b98
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/31:
 #0: ffffffff8df3d620 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8df3d620 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
 #0: ffffffff8df3d620 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
2 locks held by getty/5583:
 #0: ffff88814dc750a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc900036bb2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x43e/0x1400 drivers/tty/n_tty.c:2222
2 locks held by syz-executor/5839:
1 lock held by syz.6.1727/11551:
1 lock held by syz.0.1729/11558:
 #0: ffff888078654d20 (&mm->mmap_lock){++++}-{4:4}, at: mmap_write_lock_killable include/linux/mmap_lock.h:330 [inline]
 #0: ffff888078654d20 (&mm->mmap_lock){++++}-{4:4}, at: vm_mmap_pgoff+0x211/0x4d0 mm/util.c:579
4 locks held by syz.0.1729/11561:

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

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 31 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
 <TASK>
 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:332 [inline]
 watchdog+0xf60/0xfa0 kernel/hung_task.c:495
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158
 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: 5181 Comm: klogd Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:sock_def_readable+0x4/0x550 net/core/sock.c:3543
Code: b2 54 ff ff e8 dd 1d a1 f8 5b 41 5c 41 5e 41 5f e9 4c 58 f1 f7 cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa <55> 41 57 41 56 41 55 41 54 53 50 48 89 fb 49 bd 00 00 00 00 00 fc
RSP: 0018:ffffc90003e1fa98 EFLAGS: 00000246
RAX: 1ffff1100473d8b1 RBX: 0000000000000058 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffff8880239ec400
RBP: ffffc90003e1fc70 R08: ffff8880239ecac3 R09: 1ffff1100473d958
R10: dffffc0000000000 R11: ffffffff891ee8d0 R12: ffff8880239ec400
R13: ffff888078c233c0 R14: dffffc0000000000 R15: 1ffff920007c3f74
FS:  00007f12a62f0c80(0000) GS:ffff88812613d000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000208030 CR3: 0000000030e5d000 CR4: 0000000000350ef0
Call Trace:
 <TASK>
 unix_dgram_sendmsg+0xe08/0x1850 net/unix/af_unix.c:2309
 sock_sendmsg_nosec net/socket.c:727 [inline]
 __sock_sendmsg+0x21c/0x270 net/socket.c:742
 __sys_sendto+0x3bd/0x520 net/socket.c:2244
 __do_sys_sendto net/socket.c:2251 [inline]
 __se_sys_sendto net/socket.c:2247 [inline]
 __x64_sys_sendto+0xde/0x100 net/socket.c:2247
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f12a6440407
Code: 48 89 fa 4c 89 df e8 38 aa 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff
RSP: 002b:00007ffcc769b2d0 EFLAGS: 00000202 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007f12a62f0c80 RCX: 00007f12a6440407
RDX: 0000000000000058 RSI: 00007ffcc769b410 RDI: 0000000000000003
RBP: 00007ffcc769b840 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000004000 R11: 0000000000000202 R12: 00007ffcc769b858
R13: 00007ffcc769b410 R14: 000000000000003d R15: 00007ffcc769b410
 </TASK>