kauditd_printk_skb: 174 callbacks suppressed audit: type=1326 audit(1513899717.611:2136): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 pid=21371 comm="syz-executor0" exe="/root/syz-executor0" sig=0 arch=c000003e syscall=202 compat=0 ip=0x452a09 code=0x7ffc0000 kasan: CONFIG_KASAN_INLINE enabled kasan: GPF could be caused by NULL-ptr deref or user memory access general protection fault: 0000 [#1] SMP KASAN Dumping ftrace buffer: (ftrace buffer empty) Modules linked in: CPU: 1 PID: 21373 Comm: syz-executor1 Not tainted 4.15.0-rc4-mm1+ #47 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:__fire_sched_out_preempt_notifiers kernel/sched/core.c:2550 [inline] RIP: 0010:fire_sched_out_preempt_notifiers kernel/sched/core.c:2558 [inline] RIP: 0010:prepare_task_switch kernel/sched/core.c:2594 [inline] RIP: 0010:context_switch kernel/sched/core.c:2765 [inline] RIP: 0010:__schedule+0xdf0/0x2060 kernel/sched/core.c:3376 RSP: 0018:ffff8801d9b57ac0 EFLAGS: 00010806 RAX: 1bd5a00000000022 RBX: ffff8801db32c900 RCX: ffffffff810caeaf RDX: 000000000000017d RSI: 0000000000000000 RDI: dead000000000110 RBP: ffff8801d9b57c90 R08: 0000000000000000 R09: 1ffff1003b36af2c R10: ffff8801d9b57928 R11: 0000000000000001 R12: ffff8801c1888180 R13: dead000000000100 R14: dffffc0000000000 R15: ffff8801c1f062c0 FS: 00007f2b99e14700(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000020a08000 CR3: 00000001d5102006 CR4: 00000000001626e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: schedule+0xf5/0x430 kernel/sched/core.c:3435 exit_to_usermode_loop+0x1d1/0x2f0 arch/x86/entry/common.c:151 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline] syscall_return_slowpath+0x490/0x550 arch/x86/entry/common.c:264 entry_SYSCALL_64_fastpath+0x94/0x96 RIP: 0033:0x452a09 RSP: 002b:00007f2b99e13c88 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: 0000000000000001 RBX: 000000000071bea0 RCX: 0000000000452a09 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 000000000071becc RBP: 000000000000023c R08: 0000000000000000 R09: 000000000000023c R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006f0640 R13: 00000000ffffffff R14: 00007f2b99e146d4 R15: 0000000000000000 Code: 08 4c 89 e8 48 c1 e8 03 42 80 3c 30 00 0f 85 ce 0f 00 00 4d 8b 6d 00 4d 85 ed 0f 84 72 f9 ff ff 49 8d 7d 10 48 89 f8 48 c1 e8 03 <42> 80 3c 30 00 74 ac eb a5 49 8d bc 24 28 04 00 00 48 b8 00 00 RIP: __fire_sched_out_preempt_notifiers kernel/sched/core.c:2550 [inline] RSP: ffff8801d9b57ac0 RIP: fire_sched_out_preempt_notifiers kernel/sched/core.c:2558 [inline] RSP: ffff8801d9b57ac0 RIP: prepare_task_switch kernel/sched/core.c:2594 [inline] RSP: ffff8801d9b57ac0 RIP: context_switch kernel/sched/core.c:2765 [inline] RSP: ffff8801d9b57ac0 RIP: __schedule+0xdf0/0x2060 kernel/sched/core.c:3376 RSP: ffff8801d9b57ac0 ====================================================== WARNING: possible circular locking dependency detected 4.15.0-rc4-mm1+ #47 Not tainted ------------------------------------------------------ syz-executor1/21373 is trying to acquire lock: ((console_sem).lock){-.-.}, at: [<0000000094905fef>] down_trylock+0x13/0x70 kernel/locking/semaphore.c:136 but task is already holding lock: (&rq->lock){-.-.}, at: [<000000000ea3eebe>] rq_lock kernel/sched/sched.h:1766 [inline] (&rq->lock){-.-.}, at: [<000000000ea3eebe>] __schedule+0x24e/0x2060 kernel/sched/core.c:3313 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&rq->lock){-.-.}: __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:144 rq_lock kernel/sched/sched.h:1766 [inline] task_fork_fair+0x7a/0x690 kernel/sched/fair.c:9448 sched_fork+0x435/0xc00 kernel/sched/core.c:2405 copy_process.part.37+0x1758/0x4b60 kernel/fork.c:1776 copy_process kernel/fork.c:1619 [inline] _do_fork+0x1f7/0xf70 kernel/fork.c:2100 kernel_thread+0x34/0x40 kernel/fork.c:2159 rest_init+0x22/0xf0 init/main.c:402 start_kernel+0x7f1/0x819 init/main.c:716 x86_64_start_reservations+0x2a/0x2c arch/x86/kernel/head64.c:378 x86_64_start_kernel+0x77/0x7a arch/x86/kernel/head64.c:359 secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:237 -> #1 (&p->pi_lock){-.-.}: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x96/0xc0 kernel/locking/spinlock.c:152 try_to_wake_up+0xbc/0x1600 kernel/sched/core.c:1989 wake_up_process+0x10/0x20 kernel/sched/core.c:2152 __up.isra.0+0x1cc/0x2c0 kernel/locking/semaphore.c:262 up+0x13b/0x1d0 kernel/locking/semaphore.c:187 __up_console_sem+0xb2/0x1a0 kernel/printk/printk.c:245 console_unlock+0x538/0xd70 kernel/printk/printk.c:2248 do_con_write+0x106e/0x1f70 drivers/tty/vt/vt.c:2433 con_write+0x25/0xb0 drivers/tty/vt/vt.c:2782 process_output_block drivers/tty/n_tty.c:579 [inline] n_tty_write+0x5ef/0xec0 drivers/tty/n_tty.c:2302 do_tty_write drivers/tty/tty_io.c:949 [inline] tty_write+0x3fa/0x840 drivers/tty/tty_io.c:1033 __vfs_write+0xef/0x970 fs/read_write.c:480 vfs_write+0x189/0x510 fs/read_write.c:544 SYSC_write fs/read_write.c:589 [inline] SyS_write+0xef/0x220 fs/read_write.c:581 entry_SYSCALL_64_fastpath+0x1f/0x96 -> #0 ((console_sem).lock){-.-.}: lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:3914 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x96/0xc0 kernel/locking/spinlock.c:152 down_trylock+0x13/0x70 kernel/locking/semaphore.c:136 __down_trylock_console_sem+0xa2/0x1e0 kernel/printk/printk.c:228 console_trylock+0x15/0x100 kernel/printk/printk.c:2065 vprintk_emit+0x49b/0x590 kernel/printk/printk.c:1756 vprintk_default+0x28/0x30 kernel/printk/printk.c:1796 vprintk_func+0x57/0xc0 kernel/printk/printk_safe.c:379 printk+0xaa/0xca kernel/printk/printk.c:1829 kasan_die_handler+0x31/0x3f arch/x86/mm/kasan_init_64.c:242 notifier_call_chain+0x136/0x2c0 kernel/notifier.c:93 __atomic_notifier_call_chain kernel/notifier.c:183 [inline] atomic_notifier_call_chain+0x77/0x140 kernel/notifier.c:193 notify_die+0x18c/0x280 kernel/notifier.c:549 do_general_protection+0x331/0x3e0 arch/x86/kernel/traps.c:557 general_protection+0x2c/0x60 arch/x86/entry/entry_64.S:1242 __fire_sched_out_preempt_notifiers kernel/sched/core.c:2550 [inline] fire_sched_out_preempt_notifiers kernel/sched/core.c:2558 [inline] prepare_task_switch kernel/sched/core.c:2594 [inline] context_switch kernel/sched/core.c:2765 [inline] __schedule+0xdf0/0x2060 kernel/sched/core.c:3376 schedule+0xf5/0x430 kernel/sched/core.c:3435 exit_to_usermode_loop+0x1d1/0x2f0 arch/x86/entry/common.c:151 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline] syscall_return_slowpath+0x490/0x550 arch/x86/entry/common.c:264 entry_SYSCALL_64_fastpath+0x94/0x96 other info that might help us debug this: Chain exists of: (console_sem).lock --> &p->pi_lock --> &rq->lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&rq->lock); lock(&p->pi_lock); lock(&rq->lock); lock((console_sem).lock); *** DEADLOCK *** 2 locks held by syz-executor1/21373: #0: (&rq->lock){-.-.}, at: [<000000000ea3eebe>] rq_lock kernel/sched/sched.h:1766 [inline] #0: (&rq->lock){-.-.}, at: [<000000000ea3eebe>] __schedule+0x24e/0x2060 kernel/sched/core.c:3313 #1: (rcu_read_lock){....}, at: [<0000000065a785d2>] rcu_read_unlock include/linux/rcupdate.h:682 [inline] #1: (rcu_read_lock){....}, at: [<0000000065a785d2>] atomic_notifier_call_chain+0x0/0x140 kernel/notifier.c:184 stack backtrace: CPU: 1 PID: 21373 Comm: syz-executor1 Not tainted 4.15.0-rc4-mm1+ #47 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+0x194/0x257 lib/dump_stack.c:53 print_circular_bug.isra.37+0x2cd/0x2dc kernel/locking/lockdep.c:1218 check_prev_add kernel/locking/lockdep.c:1858 [inline] check_prevs_add kernel/locking/lockdep.c:1971 [inline] validate_chain kernel/locking/lockdep.c:2412 [inline] __lock_acquire+0x30a8/0x3e00 kernel/locking/lockdep.c:3426 lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:3914 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x96/0xc0 kernel/locking/spinlock.c:152 down_trylock+0x13/0x70 kernel/locking/semaphore.c:136 __down_trylock_console_sem+0xa2/0x1e0 kernel/printk/printk.c:228 console_trylock+0x15/0x100 kernel/printk/printk.c:2065 vprintk_emit+0x49b/0x590 kernel/printk/printk.c:1756 vprintk_default+0x28/0x30 kernel/printk/printk.c:1796 vprintk_func+0x57/0xc0 kernel/printk/printk_safe.c:379 printk+0xaa/0xca kernel/printk/printk.c:1829 kasan_die_handler+0x31/0x3f arch/x86/mm/kasan_init_64.c:242 notifier_call_chain+0x136/0x2c0 kernel/notifier.c:93 __atomic_notifier_call_chain kernel/notifier.c:183 [inline] atomic_notifier_call_chain+0x77/0x140 kernel/notifier.c:193 notify_die+0x18c/0x280 kernel/notifier.c:549 do_general_protection+0x331/0x3e0 arch/x86/kernel/traps.c:557 general_protection+0x2c/0x60 arch/x86/entry/entry_64.S:1242 RIP: 0010:__fire_sched_out_preempt_notifiers kernel/sched/core.c:2550 [inline] RIP: 0010:fire_sched_out_preempt_notifiers kernel/sched/core.c:2558 [inline] RIP: 0010:prepare_task_switch kernel/sched/core.c:2594 [inline] RIP: 0010:context_switch kernel/sched/core.c:2765 [inline] RIP: 0010:__schedule+0xdf0/0x2060 kernel/sched/core.c:3376 RSP: 0018:ffff8801d9b57ac0 EFLAGS: 00010806 RAX: 1bd5a00000000022 RBX: ffff8801db32c900 RCX: ffffffff810caeaf RDX: 000000000000017d RSI: 0000000000000000 RDI: dead000000000110 RBP: ffff8801d9b57c90 R08: 0000000000000000 R09: 1ffff1003b36af2c R10: ffff8801d9b57928 R11: 0000000000000001 R12: ffff8801c1888180 R13: dead000000000100 R14: dffffc0000000000 R15: ffff8801c1f062c0 schedule+0xf5/0x430 kernel/sched/core.c:3435 exit_to_usermode_loop+0x1d1/0x2f0 arch/x86/entry/common.c:151 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline] syscall_return_slowpath+0x490/0x550 arch/x86/entry/common.c:264 entry_SYSCALL_64_fastpath+0x94/0x96 RIP: 0033:0x452a09 RSP: 002b:00007f2b99e13c88 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: 0000000000000001 RBX: 000000000071bea0 RCX: 0000000000452a09 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 000000000071becc RBP: 000000000000023c R08: 0000000000000000 R09: 000000000000023c R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006f0640 R13: 00000000ffffffff R14: 00007f2b99e146d4 R15: 0000000000000000 ---[ end trace 6886c6676bcaadad ]---