INFO: task syz-executor2:9892 blocked for more than 120 seconds. Not tainted 4.4.105-g8a53962 #3 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor2 D ffff8801d60977d8 29144 9892 3557 0x00000004 ffff8801d60977d8 dffffc0000000000 ffff8800b948cfb0 ffff8801d60977b8 ffffffff81229f2f ffff8800b948cf00 ffff8801db51f838 ffff8801db51f860 ffff8801db51ef58 ffff8801d63edf00 ffff8800b948c740 ffff8801d6090000 Call Trace: [] schedule+0x9a/0x1c0 /syzkaller/managers/android-44-kasan-gce/kernel/kernel/sched/core.c:3351 [] rwsem_down_read_failed+0x1bf/0x300 /syzkaller/managers/android-44-kasan-gce/kernel/kernel/locking/rwsem-xadd.c:250 [] call_rwsem_down_read_failed+0x14/0x30 /syzkaller/managers/android-44-kasan-gce/kernel/arch/x86/lib/rwsem.S:90 [] n_tty_read+0xcc7/0x1c30 /syzkaller/managers/android-44-kasan-gce/kernel/drivers/tty/n_tty.c:2256 [] tty_read+0x13c/0x210 /syzkaller/managers/android-44-kasan-gce/kernel/drivers/tty/tty_io.c:1071 [] do_loop_readv_writev+0x11c/0x1e0 /syzkaller/managers/android-44-kasan-gce/kernel/fs/read_write.c:680 [] do_readv_writev+0x552/0x660 /syzkaller/managers/android-44-kasan-gce/kernel/fs/read_write.c:810 [] vfs_readv+0x5a/0xa0 /syzkaller/managers/android-44-kasan-gce/kernel/fs/read_write.c:834 [] SYSC_readv /syzkaller/managers/android-44-kasan-gce/kernel/fs/read_write.c:860 [inline] [] SyS_readv+0xd3/0x260 /syzkaller/managers/android-44-kasan-gce/kernel/fs/read_write.c:852 [] entry_SYSCALL_64_fastpath+0x16/0x76 3 locks held by syz-executor2/9892: #0: (&tty->ldisc_sem){++++++}, at: [] tty_ldisc_ref_wait+0x1d/0xa0 /syzkaller/managers/android-44-kasan-gce/kernel/drivers/tty/tty_ldisc.c:264 #1: (&ldata->atomic_read_lock){+.+.+.}, at: [] n_tty_read+0x1fd/0x1c30 /syzkaller/managers/android-44-kasan-gce/kernel/drivers/tty/n_tty.c:2180 #2: (&o_tty->termios_rwsem/1){++++.+}, at: [] n_tty_read+0xcc7/0x1c30 /syzkaller/managers/android-44-kasan-gce/kernel/drivers/tty/n_tty.c:2256 Sending NMI to all CPUs: NMI backtrace for cpu 0 CPU: 0 PID: 483 Comm: khungtaskd Not tainted 4.4.105-g8a53962 #3 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff8801d9e1df00 task.stack: ffff8801d9c68000 RIP: 0010:[] [] native_apic_mem_write /syzkaller/managers/android-44-kasan-gce/kernel/./arch/x86/include/asm/apic.h:94 [inline] RIP: 0010:[] [] __default_send_IPI_dest_field /syzkaller/managers/android-44-kasan-gce/kernel/./arch/x86/include/asm/ipi.h:119 [inline] RIP: 0010:[] [] _flat_send_IPI_mask /syzkaller/managers/android-44-kasan-gce/kernel/arch/x86/kernel/apic/apic_flat_64.c:61 [inline] RIP: 0010:[] [] flat_send_IPI_mask+0xf7/0x1a0 /syzkaller/managers/android-44-kasan-gce/kernel/arch/x86/kernel/apic/apic_flat_64.c:69 RSP: 0018:ffff8801d9c6fcb8 EFLAGS: 00000046 RAX: 0000000003000000 RBX: 0000000000000c00 RCX: 0000000000000000 RDX: 0000000000000c00 RSI: 0000000000000000 RDI: ffffffffff5fb300 RBP: ffff8801d9c6fce0 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000246 R13: 0000000000000003 R14: ffffffff8426ace0 R15: 0000000000000002 FS: 0000000000000000(0000) GS:ffff8801db400000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000c422231000 CR3: 00000000b7f1d000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Stack: ffffffff8426ace0 ffffffff847e73c0 ffffffff847e4964 0000000000000001 dffffc0000000000 ffff8801d9c6fd00 ffffffff810b62ab fffffbfff08fc92c 0000000000019460 ffff8801d9c6fd68 ffffffff81cd3e38 ffff8801d9c6fd28 Call Trace: [] nmi_raise_cpu_backtrace+0x5b/0x70 /syzkaller/managers/android-44-kasan-gce/kernel/arch/x86/kernel/apic/hw_nmi.c:33 [] nmi_trigger_all_cpu_backtrace+0x428/0x590 /syzkaller/managers/android-44-kasan-gce/kernel/lib/nmi_backtrace.c:85 [] arch_trigger_all_cpu_backtrace+0x14/0x20 /syzkaller/managers/android-44-kasan-gce/kernel/arch/x86/kernel/apic/hw_nmi.c:38 [] trigger_all_cpu_backtrace /syzkaller/managers/android-44-kasan-gce/kernel/include/linux/nmi.h:44 [inline] [] check_hung_task /syzkaller/managers/android-44-kasan-gce/kernel/kernel/hung_task.c:125 [inline] [] check_hung_uninterruptible_tasks /syzkaller/managers/android-44-kasan-gce/kernel/kernel/hung_task.c:182 [inline] [] watchdog+0x636/0xa20 /syzkaller/managers/android-44-kasan-gce/kernel/kernel/hung_task.c:238 [] kthread+0x245/0x310 /syzkaller/managers/android-44-kasan-gce/kernel/kernel/kthread.c:211 [] ret_from_fork+0x3f/0x70 /syzkaller/managers/android-44-kasan-gce/kernel/arch/x86/entry/entry_64.S:468 Code: b3 5f ff f6 c4 10 75 e1 44 89 e8 c1 e0 18 89 04 25 10 b3 5f ff 44 89 fa 09 da 80 cf 04 41 83 ff 02 0f 44 d3 89 14 25 00 b3 5f ff <41> f7 c4 00 02 00 00 74 1a e8 8b 9d 16 00 4c 89 e7 57 9d 0f 1f NMI backtrace for cpu 1 CPU: 1 PID: 9876 Comm: syz-executor2 Not tainted 4.4.105-g8a53962 #3 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff8800b8a3af80 task.stack: ffff8801d0ce0000 RIP: 0010:[] [] variable_test_bit /syzkaller/managers/android-44-kasan-gce/kernel/./arch/x86/include/asm/bitops.h:318 [inline] RIP: 0010:[] [] inq_canon /syzkaller/managers/android-44-kasan-gce/kernel/drivers/tty/n_tty.c:2477 [inline] RIP: 0010:[] [] n_tty_ioctl+0x1e7/0x2c0 /syzkaller/managers/android-44-kasan-gce/kernel/drivers/tty/n_tty.c:2497 RSP: 0018:ffff8801d0ce7b70 EFLAGS: 00000202 RAX: ffffffffffffffff RBX: dffffc0000000000 RCX: 0000000000000000 RDX: ffff8800b7c6e748 RSI: 0000000000000000 RDI: ffffc90001179268 RBP: ffff8801d0ce7bb8 R08: ffffc90001178060 R09: ffffffff850e61a0 R10: 0000000000000001 R11: 1ffff1003a19cf34 R12: 00000000209a3ffc R13: ffffc90001177000 R14: 00000008e7b8ecdc R15: 0000000000000cdc FS: 00007ff6a1644700(0000) GS:ffff8801db500000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fe665c8f9ce CR3: 00000000b7fc8000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Stack: ffffffff83749bec ffffffff81f1586d ffff8800b7c6e510 ffff8800b7c6e748 ffff8800b7c6e510 1ffff1003a19cf7d ffff8800b8ae5b00 000000000000541b ffffffffffffffea ffff8801d0ce7db0 ffffffff81eff2b5 ffff8801d0ce7e18 Call Trace: [] tty_ioctl+0x675/0x1fa0 /syzkaller/managers/android-44-kasan-gce/kernel/drivers/tty/tty_io.c:2980 [] vfs_ioctl /syzkaller/managers/android-44-kasan-gce/kernel/fs/ioctl.c:43 [inline] [] do_vfs_ioctl+0x681/0xe10 /syzkaller/managers/android-44-kasan-gce/kernel/fs/ioctl.c:607 [] SYSC_ioctl /syzkaller/managers/android-44-kasan-gce/kernel/fs/ioctl.c:622 [inline] [] SyS_ioctl+0x74/0x80 /syzkaller/managers/android-44-kasan-gce/kernel/fs/ioctl.c:613 [] entry_SYSCALL_64_fastpath+0x16/0x76 Code: 0f 84 33 ff ff ff 4d 8d 85 60 10 00 00 48 89 f0 48 bb 00 00 00 00 00 fc ff df 4c 29 f0 4d 89 f7 41 81 e7 ff 0f 00 00 4d 0f a3 38 <19> c9 85 c9 74 2c 4b 8d 7c 3d 5e 48 89 f9 49 89 f9 48 c1 e9 03