INFO: task syz-executor0:24454 blocked for more than 140 seconds.
      Not tainted 4.9.131+ #50
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor0   D28824 24454   2105 0x80000004
 ffff8801ce0caf80 ffff8801d6959b80 ffff8801d6959b80 ffff8801ad8cc740
 ffff8801db621018 ffff880177677830 ffffffff827f3542 ffff880177677808
 ffffffff81206b77 0000000000000000 00ff8801ce0cb828 ffff8801db6218f0
Call Trace:
 [<ffffffff827f4a6f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3553
 [<ffffffff827ff7cc>] rwsem_down_read_failed+0x26c/0x400 kernel/locking/rwsem-xadd.c:260
 [<ffffffff81b69578>] call_rwsem_down_read_failed+0x18/0x30 arch/x86/lib/rwsem.S:94
 [<ffffffff827fd5a2>] __down_read arch/x86/include/asm/rwsem.h:65 [inline]
 [<ffffffff827fd5a2>] down_read+0x52/0xb0 kernel/locking/rwsem.c:24
 [<ffffffff810e67a1>] exit_mm kernel/exit.c:480 [inline]
 [<ffffffff810e67a1>] do_exit+0x3c1/0x29d0 kernel/exit.c:820
 [<ffffffff810ed241>] do_group_exit+0x111/0x300 kernel/exit.c:937
 [<ffffffff8110e9e1>] get_signal+0x4e1/0x1460 kernel/signal.c:2321
 [<ffffffff81052995>] do_signal+0x95/0x1b00 arch/x86/kernel/signal.c:807
 [<ffffffff81003e2e>] exit_to_usermode_loop+0x10e/0x150 arch/x86/entry/common.c:158
 [<ffffffff81005932>] prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline]
 [<ffffffff81005932>] syscall_return_slowpath arch/x86/entry/common.c:263 [inline]
 [<ffffffff81005932>] do_syscall_64+0x3e2/0x550 arch/x86/entry/common.c:290
 [<ffffffff828037d3>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

Showing all locks held in the system:
2 locks held by khungtaskd/24:
 #0:  (rcu_read_lock){......}, at: [<ffffffff8131bbcc>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff8131bbcc>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff813fe394>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
2 locks held by getty/2018:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82801892>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81d2b2b2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
1 lock held by syz-executor0/24454:
 #0:  (&mm->mmap_sem){++++++}, at: [<ffffffff810e67a1>] exit_mm kernel/exit.c:480 [inline]
 #0:  (&mm->mmap_sem){++++++}, at: [<ffffffff810e67a1>] do_exit+0x3c1/0x29d0 kernel/exit.c:820
1 lock held by syz-executor0/24476:
 #0:  (&mm->mmap_sem){++++++}, at: [<ffffffff810e67a1>] exit_mm kernel/exit.c:480 [inline]
 #0:  (&mm->mmap_sem){++++++}, at: [<ffffffff810e67a1>] do_exit+0x3c1/0x29d0 kernel/exit.c:820
1 lock held by syz-executor0/24482:
 #0:  (&mm->mmap_sem){++++++}, at: [<ffffffff810e67a1>] exit_mm kernel/exit.c:480 [inline]
 #0:  (&mm->mmap_sem){++++++}, at: [<ffffffff810e67a1>] do_exit+0x3c1/0x29d0 kernel/exit.c:820

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

NMI backtrace for cpu 1
CPU: 1 PID: 24 Comm: khungtaskd Not tainted 4.9.131+ #50
 ffff8801d9907d08 ffffffff81b37029 0000000000000000 0000000000000001
 0000000000000001 0000000000000001 ffffffff81098450 ffff8801d9907d40
 ffffffff81b42139 0000000000000001 0000000000000000 0000000000000003
Call Trace:
 [<ffffffff81b37029>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81b37029>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81b42139>] nmi_cpu_backtrace.cold.0+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81b420cc>] nmi_trigger_cpumask_backtrace+0x12c/0x151 lib/nmi_backtrace.c:60
 [<ffffffff81098554>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff8131c15d>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff8131c15d>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff8131c15d>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff8131c15d>] watchdog+0x6ad/0xa20 kernel/hung_task.c:239
 [<ffffffff811429fd>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff8280399c>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 24483 Comm: syz-executor0 Not tainted 4.9.131+ #50
task: ffff8801a0d0df00 task.stack: ffff8801caf78000
RIP: 0010:[<ffffffff81202a25>] 
c [<ffffffff81202a25>] arch_local_save_flags arch/x86/include/asm/paravirt.h:763 [inline]
RIP: 0010:[<ffffffff81202a25>] 
c [<ffffffff81202a25>] arch_local_irq_save arch/x86/include/asm/paravirt.h:785 [inline]
RIP: 0010:[<ffffffff81202a25>] 
c [<ffffffff81202a25>] lock_is_held+0x55/0x140 kernel/locking/lockdep.c:3790
RSP: 0018:ffff8801caf7fa90  EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffff8801a0d0df00 RCX: ffffc90001736000
RDX: 0000000000000000 RSI: 000000000000026c RDI: ffff8801a0d0e7ac
RBP: ffff8801caf7fab0 R08: ffff8801a0d0e7d0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: ffffffff830cc320 R14: 000000000000026c R15: ffff8801ce0b8aa8
FS:  00007fb565997700(0000) GS:ffff8801db600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000001712978 CR3: 00000001d265f000 CR4: 00000000001606b0
DR0: 0000000020000000 DR1: 00000000200001c0 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Stack:
 0000000000000246
c ffff8801a0d0df00
c 0000000000000000
c ffffffff82a4f760
c
 ffff8801caf7fae8
c ffffffff8116782f
c ffff8801a0d0df00
c ffffffff82a4f760
c
 000000000000026c
c 0000000000000000
c ffff8801ce0b8aa8
c ffff8801caf7fb28
c
Call Trace:
 [<ffffffff8116782f>] ___might_sleep+0x1ff/0x260 kernel/sched/core.c:7954
 [<ffffffff81167925>] __might_sleep+0x95/0x1a0 kernel/sched/core.c:7945
 [<ffffffff827f7167>] mutex_lock_nested+0x87/0x900 kernel/locking/mutex.c:620
 [<ffffffff813d97d7>] perf_mmap+0x4f7/0x1430 kernel/events/core.c:5265
 [<ffffffff814b41fc>] mmap_region+0x80c/0xf90 mm/mmap.c:1726
 [<ffffffff814b4ebd>] do_mmap+0x53d/0xbb0 mm/mmap.c:1505
 [<ffffffff81469ec8>] do_mmap_pgoff include/linux/mm.h:2032 [inline]
 [<ffffffff81469ec8>] vm_mmap_pgoff+0x168/0x1b0 mm/util.c:329
 [<ffffffff814af56e>] SYSC_mmap_pgoff mm/mmap.c:1555 [inline]
 [<ffffffff814af56e>] SyS_mmap_pgoff+0xfe/0x1b0 mm/mmap.c:1513
 [<ffffffff8105d2b6>] SYSC_mmap arch/x86/kernel/sys_x86_64.c:96 [inline]
 [<ffffffff8105d2b6>] SyS_mmap+0x16/0x20 arch/x86/kernel/sys_x86_64.c:87
 [<ffffffff810056ef>] do_syscall_64+0x19f/0x550 arch/x86/entry/common.c:285
 [<ffffffff828037d3>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
Code: 
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c