syzbot

binder: undelivered TRANSACTION_ERROR: 29201
SELinux: unrecognized netlink message: protocol=0 nlmsg_type=0 sclass=netlink_route_socket pig=13209 comm=syz-executor3
SELinux: unrecognized netlink message: protocol=0 nlmsg_type=65535 sclass=netlink_route_socket pig=13198 comm=syz-executor3
SELinux: unrecognized netlink message: protocol=0 nlmsg_type=0 sclass=netlink_route_socket pig=13212 comm=syz-executor3
INFO: task syz-executor6:2036 blocked for more than 140 seconds.
      Not tainted 4.14.67+ #1
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor6   D28472  2036   1991 0x80000004
Call Trace:
 schedule+0x7f/0x1b0 kernel/sched/core.c:3490
 __rwsem_down_write_failed_common kernel/locking/rwsem-xadd.c:565 [inline]
 rwsem_down_write_failed+0x390/0x730 kernel/locking/rwsem-xadd.c:594
 call_rwsem_down_write_failed+0x13/0x20 arch/x86/lib/rwsem.S:105
 __down_write arch/x86/include/asm/rwsem.h:126 [inline]
 down_write+0x4f/0x90 kernel/locking/rwsem.c:56
 lock_anon_vma_root mm/rmap.c:238 [inline]
 unlink_anon_vmas+0x179/0x7d0 mm/rmap.c:388
 free_pgtables+0x139/0x220 mm/memory.c:634
 exit_mmap+0x208/0x420 mm/mmap.c:3069
 __mmput kernel/fork.c:929 [inline]
 mmput+0xc8/0x350 kernel/fork.c:950
 exit_mm kernel/exit.c:544 [inline]
 do_exit+0x83b/0x2800 kernel/exit.c:852
 do_group_exit+0x100/0x2e0 kernel/exit.c:968
 get_signal+0x4e5/0x1470 kernel/signal.c:2348
 do_signal+0x8f/0x1660 arch/x86/kernel/signal.c:809
 exit_to_usermode_loop+0x116/0x150 arch/x86/entry/common.c:159
 prepare_exit_to_usermode arch/x86/entry/common.c:198 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:267 [inline]
 do_syscall_64+0x35d/0x4b0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x410e7a
RSP: 002b:00007ffc53469f88 EFLAGS: 00000246 ORIG_RAX: 000000000000003d
RAX: fffffffffffffe00 RBX: 00000000000007fb RCX: 0000000000410e7a
RDX: 0000000040000000 RSI: 00007ffc53469f94 RDI: ffffffffffffffff
RBP: 0000000000930b28 R08: 00000000000007f4 R09: 0000000001053940
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000010
R13: 0000000000412a80 R14: 0000000000000000 R15: 0000000000000000

Showing all locks held in the system:
1 lock held by khungtaskd/23:
 #0:  (tasklist_lock){.+.+}, at: [<ffffffffada01847>] debug_show_all_locks+0x74/0x20f kernel/locking/lockdep.c:4541
2 locks held by getty/1962:
 #0:  (&tty->ldisc_sem){++++}, at: [<ffffffffae51c500>] tty_ldisc_ref_wait+0x20/0x80 drivers/tty/tty_ldisc.c:275
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<ffffffffae517a7f>] n_tty_read+0x1ff/0x15e0 drivers/tty/n_tty.c:2142
1 lock held by syz-executor6/2036:
 #0:  (&anon_vma->rwsem){++++}, at: [<ffffffffadcf2069>] lock_anon_vma_root mm/rmap.c:238 [inline]
 #0:  (&anon_vma->rwsem){++++}, at: [<ffffffffadcf2069>] unlink_anon_vmas+0x179/0x7d0 mm/rmap.c:388

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

NMI backtrace for cpu 0
CPU: 0 PID: 23 Comm: khungtaskd Not tainted 4.14.67+ #1
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0xb9/0x11b lib/dump_stack.c:53
 nmi_cpu_backtrace.cold.0+0x18/0x8e lib/nmi_backtrace.c:103
 nmi_trigger_cpumask_backtrace+0x121/0x146 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:138 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:196 [inline]
 watchdog+0x574/0xa70 kernel/hung_task.c:252
 kthread+0x348/0x420 kernel/kthread.c:232
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:402
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1 skipped: idling at pc 0xffffffffaf040572