INFO: task syz-executor.2:18813 blocked for more than 140 seconds.
      Not tainted 4.9.168+ #40
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.2  D28976 18813   2230 0x80000000
 ffff8801c9ce17c0 ffff8801cfb0b180 ffff8801db721000 ffff8801cfabdf00
 ffff8801db721018 ffff8801c290fba0 ffffffff8280028e 0000000041b58ab3
 ffff8801c9ce17c0 00ff8801c290faf0 ffff8801db7218f0 1ffff10038521f63
Call Trace:
 [<0000000028b37c7f>] schedule+0x92/0x1c0 kernel/sched/core.c:3546
 [<00000000eea83b25>] rwsem_down_read_failed+0x258/0x3e0 kernel/locking/rwsem-xadd.c:267
 [<000000008f2b5747>] call_rwsem_down_read_failed+0x18/0x30 arch/x86/lib/rwsem.S:94
 [<00000000223a4b23>] __down_read arch/x86/include/asm/rwsem.h:65 [inline]
 [<00000000223a4b23>] down_read+0x52/0xb0 kernel/locking/rwsem.c:24
 [<0000000051a46d13>] exit_mm kernel/exit.c:480 [inline]
 [<0000000051a46d13>] do_exit+0x3b7/0x2aa0 kernel/exit.c:828
 [<00000000b5caab24>] do_group_exit+0x111/0x300 kernel/exit.c:945
 [<000000004bc657af>] SYSC_exit_group kernel/exit.c:956 [inline]
 [<000000004bc657af>] SyS_exit_group+0x1d/0x20 kernel/exit.c:954
 [<000000003e33bf44>] do_syscall_64+0x1ad/0x570 arch/x86/entry/common.c:285
 [<0000000073b63534>] 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: [<00000000f62a06e0>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<00000000f62a06e0>] watchdog+0x13c/0xae0 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<00000000ed586e03>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4339
2 locks held by getty/2024:
 #0:  (&tty->ldisc_sem){++++++}, at: [<000000003a399664>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:377
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<0000000028c777a9>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156
1 lock held by syz-executor.2/18813:
 #0:  (&mm->mmap_sem){++++++}, at: [<0000000051a46d13>] exit_mm kernel/exit.c:480 [inline]
 #0:  (&mm->mmap_sem){++++++}, at: [<0000000051a46d13>] do_exit+0x3b7/0x2aa0 kernel/exit.c:828
1 lock held by syz-executor.2/18820:
 #0:  (&mm->mmap_sem){++++++}, at: [<0000000051a46d13>] exit_mm kernel/exit.c:480 [inline]
 #0:  (&mm->mmap_sem){++++++}, at: [<0000000051a46d13>] do_exit+0x3b7/0x2aa0 kernel/exit.c:828

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

NMI backtrace for cpu 0
CPU: 0 PID: 24 Comm: khungtaskd Not tainted 4.9.168+ #40
 ffff8801d98d7cc8 ffffffff81b4f5d1 0000000000000000 0000000000000000
 0000000000000000 ffffffff81097401 dffffc0000000000 ffff8801d98d7d00
 ffffffff81b5a86c 0000000000000000 0000000000000000 0000000000000000
Call Trace:
 [<00000000e0037114>] __dump_stack lib/dump_stack.c:15 [inline]
 [<00000000e0037114>] dump_stack+0xc1/0x120 lib/dump_stack.c:51
 [<000000000b41671f>] nmi_cpu_backtrace.cold+0x47/0x87 lib/nmi_backtrace.c:99
 [<00000000b357a724>] nmi_trigger_cpumask_backtrace+0x124/0x155 lib/nmi_backtrace.c:60
 [<00000000b4992115>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<00000000796d3f36>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<00000000796d3f36>] check_hung_task kernel/hung_task.c:125 [inline]
 [<00000000796d3f36>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<00000000796d3f36>] watchdog+0x661/0xae0 kernel/hung_task.c:239
 [<00000000dfbb3002>] kthread+0x278/0x310 kernel/kthread.c:211
 [<000000001da549f7>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 18828 Comm: syz-executor.2 Not tainted 4.9.168+ #40
task: 00000000a4ae1614 task.stack: 000000006c8331c0
RIP: 0010:[<ffffffff8131d080>] 
c [<0000000068d9999f>] __read_once_size include/linux/compiler.h:243 [inline]
RIP: 0010:[<ffffffff8131d080>] 
c [<0000000068d9999f>] check_kcov_mode kernel/kcov.c:68 [inline]
RIP: 0010:[<ffffffff8131d080>] 
c [<0000000068d9999f>] __sanitizer_cov_trace_pc+0x20/0x50 kernel/kcov.c:100
RSP: 0018:ffff8801c5c77c28  EFLAGS: 00000246
RAX: ffff8801c9ecaf80 RBX: ffff8801c6805728 RCX: 1ffff100393d970a
RDX: 0000000000000000 RSI: ffffffff813dbedf RDI: ffff8801c5c77bb0
RBP: ffff8801c5c77c28 R08: 0000000000000000 R09: ffff8801c9ecb850
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: ffff8801c636d960 R14: ffff8801d2b3c400 R15: ffff8801d2b3c6e0
FS:  00007f57efe88700(0000) GS:ffff8801db700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000f4f308 CR3: 00000001c867a000 CR4: 00000000001606b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffff8801c5c77cc0
c ffffffff813dbedf
c ffff8801c636d960
c ffff8801c5c77c68
c
 0000000000000246
c 0000000000000003
c ffff8801d2b3c6c4
c ffff8801c636d9f8
c
 ffffffff830a2140
c ffff8801d2b3c768
c 0000000000000000
c ffff8801c636d9b0
c
Call Trace:
 [<000000002384ad74>] perf_mmap+0x4cf/0x1580 kernel/events/core.c:5278
 [<00000000555e8447>] mmap_region+0x7e7/0xfa0 mm/mmap.c:1726
 [<00000000c4e0bb3d>] do_mmap+0x539/0xbc0 mm/mmap.c:1505
 [<00000000cd906feb>] do_mmap_pgoff include/linux/mm.h:2034 [inline]
 [<00000000cd906feb>] vm_mmap_pgoff+0x179/0x1c0 mm/util.c:329
 [<000000004b4bf30c>] SYSC_mmap_pgoff mm/mmap.c:1555 [inline]
 [<000000004b4bf30c>] SyS_mmap_pgoff+0xfa/0x1b0 mm/mmap.c:1513
 [<00000000e3aba7fd>] SYSC_mmap arch/x86/kernel/sys_x86_64.c:96 [inline]
 [<00000000e3aba7fd>] SyS_mmap+0x16/0x20 arch/x86/kernel/sys_x86_64.c:87
 [<000000003e33bf44>] do_syscall_64+0x1ad/0x570 arch/x86/entry/common.c:285
 [<0000000073b63534>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
Code: 
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c