bisecting fixing commit since b0cdffaa546e24acf92ab3b0d4e917a51aff6a82 building syzkaller on 4de4e9f01d7139b72102ae0b8a1e810730467774 testing commit b0cdffaa546e24acf92ab3b0d4e917a51aff6a82 with gcc (GCC) 8.1.0 kernel signature: 9bb827ee4bc1624c85b94258038d558d1a6ea3872c6c75595df529f4cdbee769 run #0: crashed: INFO: task hung in fb_open run #1: crashed: INFO: task hung in fb_open run #2: OK run #3: OK run #4: OK run #5: OK run #6: OK run #7: OK run #8: OK run #9: OK testing current HEAD e0f8b8a65a473a8baa439cf865a694bbeb83fe90 testing commit e0f8b8a65a473a8baa439cf865a694bbeb83fe90 with gcc (GCC) 8.1.0 kernel signature: 8c4c310b6240bf020bc3cb149c4d5762e54376a5810ba804b4de49c2d053c4d7 run #0: crashed: INFO: task hung in fb_open run #1: crashed: INFO: task hung in fb_open run #2: crashed: INFO: task hung in fb_open run #3: crashed: INFO: task hung in fb_open run #4: crashed: INFO: task hung in fb_open run #5: crashed: INFO: task hung in fb_open run #6: crashed: INFO: task hung in fb_open run #7: OK run #8: OK run #9: OK revisions tested: 2, total time: 39m2.954886642s (build: 16m43.154181213s, test: 21m46.241238156s) the crash still happens on HEAD commit msg: Linux 4.14.170 crash: INFO: task hung in fb_open team0 (unregistering): Port device team_slave_1 removed team0 (unregistering): Port device team_slave_0 removed bond0 (unregistering): Releasing backup interface bond_slave_1 bond0 (unregistering): Releasing backup interface bond_slave_0 bond0 (unregistering): Released all slaves INFO: task syz-executor.3:7452 blocked for more than 140 seconds. Not tainted 4.14.170-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.3 D28848 7452 7284 0x00000004 Call Trace: context_switch kernel/sched/core.c:2808 [inline] __schedule+0x780/0x1d20 kernel/sched/core.c:3384 schedule+0x7f/0x1b0 kernel/sched/core.c:3428 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3486 __mutex_lock_common kernel/locking/mutex.c:833 [inline] __mutex_lock+0xabc/0x14c0 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 fb_open+0x9f/0x390 drivers/video/fbdev/core/fbmem.c:1468 chrdev_open+0x1e9/0x5b0 fs/char_dev.c:423 do_dentry_open+0x620/0xdb0 fs/open.c:777 vfs_open+0xfc/0x240 fs/open.c:891 do_last fs/namei.c:3428 [inline] path_openat+0xdde/0x3be0 fs/namei.c:3569 do_filp_open+0x16b/0x220 fs/namei.c:3603 do_sys_open+0x1c2/0x340 fs/open.c:1084 SYSC_openat fs/open.c:1111 [inline] SyS_openat+0xf/0x20 fs/open.c:1105 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x45af49 RSP: 002b:00007fa79437fc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 000000000045af49 RDX: 0000000000000000 RSI: 0000000020000180 RDI: ffffffffffffff9c RBP: 000000000075bfc8 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007fa7943806d4 R13: 00000000004c88ce R14: 00000000004e0e30 R15: 00000000ffffffff INFO: task syz-executor.2:7394 blocked for more than 140 seconds. Not tainted 4.14.170-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.2 D29304 7394 7287 0x00000004 Call Trace: context_switch kernel/sched/core.c:2808 [inline] __schedule+0x780/0x1d20 kernel/sched/core.c:3384 schedule+0x7f/0x1b0 kernel/sched/core.c:3428 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3486 __mutex_lock_common kernel/locking/mutex.c:833 [inline] __mutex_lock+0xabc/0x14c0 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 fb_open+0x9f/0x390 drivers/video/fbdev/core/fbmem.c:1468 chrdev_open+0x1e9/0x5b0 fs/char_dev.c:423 do_dentry_open+0x620/0xdb0 fs/open.c:777 vfs_open+0xfc/0x240 fs/open.c:891 do_last fs/namei.c:3428 [inline] path_openat+0xdde/0x3be0 fs/namei.c:3569 do_filp_open+0x16b/0x220 fs/namei.c:3603 do_sys_open+0x1c2/0x340 fs/open.c:1084 SYSC_openat fs/open.c:1111 [inline] SyS_openat+0xf/0x20 fs/open.c:1105 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x45af49 RSP: 002b:00007f2fa6957c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 000000000045af49 RDX: 0000000000000000 RSI: 0000000020000180 RDI: ffffffffffffff9c RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f2fa69586d4 R13: 00000000004c88ce R14: 00000000004e0e30 R15: 00000000ffffffff INFO: task syz-executor.2:7399 blocked for more than 140 seconds. Not tainted 4.14.170-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.2 D29304 7399 7287 0x00000004 Call Trace: context_switch kernel/sched/core.c:2808 [inline] __schedule+0x780/0x1d20 kernel/sched/core.c:3384 schedule+0x7f/0x1b0 kernel/sched/core.c:3428 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3486 __mutex_lock_common kernel/locking/mutex.c:833 [inline] __mutex_lock+0xabc/0x14c0 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 fb_open+0x9f/0x390 drivers/video/fbdev/core/fbmem.c:1468 chrdev_open+0x1e9/0x5b0 fs/char_dev.c:423 do_dentry_open+0x620/0xdb0 fs/open.c:777 vfs_open+0xfc/0x240 fs/open.c:891 do_last fs/namei.c:3428 [inline] path_openat+0xdde/0x3be0 fs/namei.c:3569 do_filp_open+0x16b/0x220 fs/namei.c:3603 do_sys_open+0x1c2/0x340 fs/open.c:1084 SYSC_openat fs/open.c:1111 [inline] SyS_openat+0xf/0x20 fs/open.c:1105 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x45af49 RSP: 002b:00007f2fa6936c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 000000000045af49 RDX: 0000000000000000 RSI: 0000000020000180 RDI: ffffffffffffff9c RBP: 000000000075bfc8 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f2fa69376d4 R13: 00000000004c88ce R14: 00000000004e0e30 R15: 00000000ffffffff INFO: task syz-executor.5:7421 blocked for more than 140 seconds. Not tainted 4.14.170-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.5 D29304 7421 7286 0x00000004 Call Trace: context_switch kernel/sched/core.c:2808 [inline] __schedule+0x780/0x1d20 kernel/sched/core.c:3384 schedule+0x7f/0x1b0 kernel/sched/core.c:3428 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3486 __mutex_lock_common kernel/locking/mutex.c:833 [inline] __mutex_lock+0xabc/0x14c0 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 fb_open+0x9f/0x390 drivers/video/fbdev/core/fbmem.c:1468 chrdev_open+0x1e9/0x5b0 fs/char_dev.c:423 do_dentry_open+0x620/0xdb0 fs/open.c:777 vfs_open+0xfc/0x240 fs/open.c:891 do_last fs/namei.c:3428 [inline] path_openat+0xdde/0x3be0 fs/namei.c:3569 do_filp_open+0x16b/0x220 fs/namei.c:3603 do_sys_open+0x1c2/0x340 fs/open.c:1084 SYSC_openat fs/open.c:1111 [inline] SyS_openat+0xf/0x20 fs/open.c:1105 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x45af49 RSP: 002b:00007f4d22bd8c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 000000000045af49 RDX: 0000000000000000 RSI: 0000000020000180 RDI: ffffffffffffff9c RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f4d22bd96d4 R13: 00000000004c88ce R14: 00000000004e0e30 R15: 00000000ffffffff INFO: task syz-executor.5:7426 blocked for more than 140 seconds. Not tainted 4.14.170-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.5 D29240 7426 7286 0x00000004 Call Trace: context_switch kernel/sched/core.c:2808 [inline] __schedule+0x780/0x1d20 kernel/sched/core.c:3384 schedule+0x7f/0x1b0 kernel/sched/core.c:3428 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3486 __mutex_lock_common kernel/locking/mutex.c:833 [inline] __mutex_lock+0xabc/0x14c0 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 fb_open+0x9f/0x390 drivers/video/fbdev/core/fbmem.c:1468 chrdev_open+0x1e9/0x5b0 fs/char_dev.c:423 do_dentry_open+0x620/0xdb0 fs/open.c:777 vfs_open+0xfc/0x240 fs/open.c:891 do_last fs/namei.c:3428 [inline] path_openat+0xdde/0x3be0 fs/namei.c:3569 do_filp_open+0x16b/0x220 fs/namei.c:3603 do_sys_open+0x1c2/0x340 fs/open.c:1084 SYSC_openat fs/open.c:1111 [inline] SyS_openat+0xf/0x20 fs/open.c:1105 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x45af49 RSP: 002b:00007f4d22bb7c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 000000000045af49 RDX: 0000000000000000 RSI: 0000000020000180 RDI: ffffffffffffff9c RBP: 000000000075bfc8 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f4d22bb86d4 R13: 00000000004c88ce R14: 00000000004e0e30 R15: 00000000ffffffff INFO: task syz-executor.0:7448 blocked for more than 140 seconds. Not tainted 4.14.170-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.0 D29304 7448 7290 0x00000004 Call Trace: context_switch kernel/sched/core.c:2808 [inline] __schedule+0x780/0x1d20 kernel/sched/core.c:3384 schedule+0x7f/0x1b0 kernel/sched/core.c:3428 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3486 __mutex_lock_common kernel/locking/mutex.c:833 [inline] __mutex_lock+0xabc/0x14c0 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 fb_open+0x9f/0x390 drivers/video/fbdev/core/fbmem.c:1468 chrdev_open+0x1e9/0x5b0 fs/char_dev.c:423 do_dentry_open+0x620/0xdb0 fs/open.c:777 vfs_open+0xfc/0x240 fs/open.c:891 do_last fs/namei.c:3428 [inline] path_openat+0xdde/0x3be0 fs/namei.c:3569 do_filp_open+0x16b/0x220 fs/namei.c:3603 do_sys_open+0x1c2/0x340 fs/open.c:1084 SYSC_openat fs/open.c:1111 [inline] SyS_openat+0xf/0x20 fs/open.c:1105 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x45af49 RSP: 002b:00007f1161e6ac78 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 000000000045af49 RDX: 0000000000000000 RSI: 0000000020000180 RDI: ffffffffffffff9c RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f1161e6b6d4 R13: 00000000004c88ce R14: 00000000004e0e30 R15: 00000000ffffffff INFO: task syz-executor.0:7450 blocked for more than 140 seconds. Not tainted 4.14.170-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.0 D28856 7450 7290 0x00000004 Call Trace: context_switch kernel/sched/core.c:2808 [inline] __schedule+0x780/0x1d20 kernel/sched/core.c:3384 schedule+0x7f/0x1b0 kernel/sched/core.c:3428 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3486 __mutex_lock_common kernel/locking/mutex.c:833 [inline] __mutex_lock+0xabc/0x14c0 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 fb_open+0x9f/0x390 drivers/video/fbdev/core/fbmem.c:1468 chrdev_open+0x1e9/0x5b0 fs/char_dev.c:423 do_dentry_open+0x620/0xdb0 fs/open.c:777 vfs_open+0xfc/0x240 fs/open.c:891 do_last fs/namei.c:3428 [inline] path_openat+0xdde/0x3be0 fs/namei.c:3569 do_filp_open+0x16b/0x220 fs/namei.c:3603 do_sys_open+0x1c2/0x340 fs/open.c:1084 SYSC_openat fs/open.c:1111 [inline] SyS_openat+0xf/0x20 fs/open.c:1105 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x45af49 RSP: 002b:00007f1161e49c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 000000000045af49 RDX: 0000000000000000 RSI: 0000000020000180 RDI: ffffffffffffff9c RBP: 000000000075bfc8 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f1161e4a6d4 R13: 00000000004c88ce R14: 00000000004e0e30 R15: 00000000ffffffff INFO: task syz-executor.1:7458 blocked for more than 140 seconds. Not tainted 4.14.170-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.1 D29304 7458 7292 0x00000004 Call Trace: context_switch kernel/sched/core.c:2808 [inline] __schedule+0x780/0x1d20 kernel/sched/core.c:3384 schedule+0x7f/0x1b0 kernel/sched/core.c:3428 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3486 __mutex_lock_common kernel/locking/mutex.c:833 [inline] __mutex_lock+0xabc/0x14c0 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 fb_open+0x9f/0x390 drivers/video/fbdev/core/fbmem.c:1468 chrdev_open+0x1e9/0x5b0 fs/char_dev.c:423 do_dentry_open+0x620/0xdb0 fs/open.c:777 vfs_open+0xfc/0x240 fs/open.c:891 do_last fs/namei.c:3428 [inline] path_openat+0xdde/0x3be0 fs/namei.c:3569 do_filp_open+0x16b/0x220 fs/namei.c:3603 do_sys_open+0x1c2/0x340 fs/open.c:1084 SYSC_openat fs/open.c:1111 [inline] SyS_openat+0xf/0x20 fs/open.c:1105 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x45af49 RSP: 002b:00007f452809fc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 000000000045af49 RDX: 0000000000000000 RSI: 0000000020000180 RDI: ffffffffffffff9c RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f45280a06d4 R13: 00000000004c88ce R14: 00000000004e0e30 R15: 00000000ffffffff INFO: task syz-executor.1:7462 blocked for more than 140 seconds. Not tainted 4.14.170-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.1 D29304 7462 7292 0x00000004 Call Trace: context_switch kernel/sched/core.c:2808 [inline] __schedule+0x780/0x1d20 kernel/sched/core.c:3384 schedule+0x7f/0x1b0 kernel/sched/core.c:3428 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3486 __mutex_lock_common kernel/locking/mutex.c:833 [inline] __mutex_lock+0xabc/0x14c0 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 fb_open+0x9f/0x390 drivers/video/fbdev/core/fbmem.c:1468 chrdev_open+0x1e9/0x5b0 fs/char_dev.c:423 do_dentry_open+0x620/0xdb0 fs/open.c:777 vfs_open+0xfc/0x240 fs/open.c:891 do_last fs/namei.c:3428 [inline] path_openat+0xdde/0x3be0 fs/namei.c:3569 do_filp_open+0x16b/0x220 fs/namei.c:3603 do_sys_open+0x1c2/0x340 fs/open.c:1084 SYSC_openat fs/open.c:1111 [inline] SyS_openat+0xf/0x20 fs/open.c:1105 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x45af49 RSP: 002b:00007f452807ec78 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 000000000045af49 RDX: 0000000000000000 RSI: 0000000020000180 RDI: ffffffffffffff9c RBP: 000000000075bfc8 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f452807f6d4 R13: 00000000004c88ce R14: 00000000004e0e30 R15: 00000000ffffffff INFO: task syz-executor.4:7461 blocked for more than 140 seconds. Not tainted 4.14.170-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.4 D28552 7461 7293 0x00000004 Call Trace: context_switch kernel/sched/core.c:2808 [inline] __schedule+0x780/0x1d20 kernel/sched/core.c:3384 schedule+0x7f/0x1b0 kernel/sched/core.c:3428 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3486 __mutex_lock_common kernel/locking/mutex.c:833 [inline] __mutex_lock+0xabc/0x14c0 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 fb_open+0x9f/0x390 drivers/video/fbdev/core/fbmem.c:1468 chrdev_open+0x1e9/0x5b0 fs/char_dev.c:423 do_dentry_open+0x620/0xdb0 fs/open.c:777 vfs_open+0xfc/0x240 fs/open.c:891 do_last fs/namei.c:3428 [inline] path_openat+0xdde/0x3be0 fs/namei.c:3569 do_filp_open+0x16b/0x220 fs/namei.c:3603 do_sys_open+0x1c2/0x340 fs/open.c:1084 SYSC_openat fs/open.c:1111 [inline] SyS_openat+0xf/0x20 fs/open.c:1105 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x45af49 RSP: 002b:00007fac071d1c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 000000000045af49 RDX: 0000000000000000 RSI: 0000000020000180 RDI: ffffffffffffff9c RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007fac071d26d4 R13: 00000000004c88ce R14: 00000000004e0e30 R15: 00000000ffffffff Showing all locks held in the system: 1 lock held by khungtaskd/1059: #0: (tasklist_lock){.+.+}, at: [] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4544 1 lock held by rsyslogd/6848: #0: (&f->f_pos_lock){+.+.}, at: [] __fdget_pos+0x8e/0xc0 fs/file.c:769 2 locks held by getty/6971: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x2d/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x18f0 drivers/tty/n_tty.c:2156 2 locks held by getty/6972: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x2d/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x18f0 drivers/tty/n_tty.c:2156 2 locks held by getty/6973: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x2d/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x18f0 drivers/tty/n_tty.c:2156 2 locks held by getty/6974: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x2d/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x18f0 drivers/tty/n_tty.c:2156 2 locks held by getty/6975: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x2d/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x18f0 drivers/tty/n_tty.c:2156 2 locks held by getty/6976: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x2d/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x18f0 drivers/tty/n_tty.c:2156 2 locks held by getty/6977: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x2d/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x18f0 drivers/tty/n_tty.c:2156 1 lock held by syz-executor.3/7452: #0: (&fb_info->lock){+.+.}, at: [] fb_open+0x9f/0x390 drivers/video/fbdev/core/fbmem.c:1468 1 lock held by syz-executor.2/7394: #0: (&fb_info->lock){+.+.}, at: [] fb_open+0x9f/0x390 drivers/video/fbdev/core/fbmem.c:1468 1 lock held by syz-executor.2/7399: #0: (&fb_info->lock){+.+.}, at: [] fb_open+0x9f/0x390 drivers/video/fbdev/core/fbmem.c:1468 1 lock held by syz-executor.5/7421: #0: (&fb_info->lock){+.+.}, at: [] fb_open+0x9f/0x390 drivers/video/fbdev/core/fbmem.c:1468 1 lock held by syz-executor.5/7426: #0: (&fb_info->lock){+.+.}, at: [] fb_open+0x9f/0x390 drivers/video/fbdev/core/fbmem.c:1468 1 lock held by syz-executor.0/7448: #0: (&fb_info->lock){+.+.}, at: [] fb_open+0x9f/0x390 drivers/video/fbdev/core/fbmem.c:1468 1 lock held by syz-executor.0/7450: #0: (&fb_info->lock){+.+.}, at: [] fb_open+0x9f/0x390 drivers/video/fbdev/core/fbmem.c:1468 1 lock held by syz-executor.1/7458: #0: (&fb_info->lock){+.+.}, at: [] fb_open+0x9f/0x390 drivers/video/fbdev/core/fbmem.c:1468 1 lock held by syz-executor.1/7462: #0: (&fb_info->lock){+.+.}, at: [] fb_open+0x9f/0x390 drivers/video/fbdev/core/fbmem.c:1468 1 lock held by syz-executor.4/7461: #0: (&fb_info->lock){+.+.}, at: [] fb_open+0x9f/0x390 drivers/video/fbdev/core/fbmem.c:1468 1 lock held by syz-executor.4/7463: #0: (&fb_info->lock){+.+.}, at: [] fb_open+0x9f/0x390 drivers/video/fbdev/core/fbmem.c:1468 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1059 Comm: khungtaskd Not tainted 4.14.170-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0xf7/0x13b lib/dump_stack.c:58 nmi_cpu_backtrace.cold.4+0x3e/0x76 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0xe5/0x119 lib/nmi_backtrace.c:62 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38 trigger_all_cpu_backtrace include/linux/nmi.h:140 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:195 [inline] watchdog+0x522/0xb40 kernel/hung_task.c:274 kthread+0x338/0x400 kernel/kthread.c:232 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 7387 Comm: syz-executor.3 Not tainted 4.14.170-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff888091c78000 task.stack: ffff8880a6698000 RIP: 0010:__writeq arch/x86/include/asm/io.h:100 [inline] RIP: 0010:bitfill_aligned+0x9a/0x120 drivers/video/fbdev/core/cfbfillrect.c:69 RSP: 0018:ffff8880a669f1a0 EFLAGS: 00000206 RAX: 0000000000000050 RBX: 0000000000001400 RCX: ffff8880000a0280 RDX: 0000000000000050 RSI: ffff8880000a00c0 RDI: 0000000000000000 RBP: ffff8880a669f1b0 R08: 0000000000001400 R09: ffff8880000a00b8 R10: 0000000000000000 R11: 0000000000000000 R12: ffffffffffffffff R13: ffff888219262e00 R14: 00000000042e61a0 R15: ffffed104324c5fc FS: 00007fa7943a1700(0000) GS:ffff8880aed00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fac0718fdb8 CR3: 00000000a66d1000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: cfb_fillrect+0x3e8/0x730 drivers/video/fbdev/core/cfbfillrect.c:327 vga16fb_fillrect+0x5ac/0x19b0 drivers/video/fbdev/vga16fb.c:951 bit_clear_margins+0x38a/0x600 drivers/video/fbdev/core/bitblit.c:232 fbcon_clear_margins+0x1b1/0x330 drivers/video/fbdev/core/fbcon.c:1317 fbcon_switch+0xbd7/0x1960 drivers/video/fbdev/core/fbcon.c:2299 redraw_screen+0x301/0x7f0 drivers/tty/vt/vt.c:688 fbcon_modechanged+0x56f/0x890 drivers/video/fbdev/core/fbcon.c:2946 fbcon_set_all_vcs+0x32c/0x4c0 drivers/video/fbdev/core/fbcon.c:2984 fbcon_event_notify+0xc50/0x1978 drivers/video/fbdev/core/fbcon.c:3302 notifier_call_chain+0xd6/0x150 kernel/notifier.c:93 __blocking_notifier_call_chain kernel/notifier.c:317 [inline] blocking_notifier_call_chain+0x6b/0xa0 kernel/notifier.c:328 fb_notifier_call_chain+0x16/0x20 drivers/video/fbdev/core/fb_notify.c:45 fb_set_var+0xabb/0xf30 drivers/video/fbdev/core/fbmem.c:1054 do_fb_ioctl+0x422/0x910 drivers/video/fbdev/core/fbmem.c:1127 fb_ioctl+0xcb/0x150 drivers/video/fbdev/core/fbmem.c:1242 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0x180/0xfb0 fs/ioctl.c:684 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x74/0x80 fs/ioctl.c:692 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x45af49 RSP: 002b:00007fa7943a0c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045af49 RDX: 0000000020000000 RSI: 0000000000004601 RDI: 0000000000000003 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007fa7943a16d4 R13: 00000000004c3903 R14: 00000000004d9f18 R15: 00000000ffffffff Code: 83 f8 07 89 c2 76 41 8d 48 f8 c1 e9 03 48 83 c1 01 48 c1 e1 06 48 01 f1 48 89 3e 48 89 7e 08 48 89 7e 10 48 89 7e 18 48 89 7e 20 <48> 89 7e 28 4c 8d 4e 38 48 89 7e 30 48 83 c6 40 49 89 39 48 39