====================================================== WARNING: possible circular locking dependency detected 4.13.0-mm1+ #3 Not tainted ------------------------------------------------------ syz-executor0/5642 is trying to acquire lock: (console_lock){+.+.}, at: [] vcs_write+0x14d/0xca0 drivers/tty/vt/vc_screen.c:396 but task is already holding lock: (&pipe->mutex/1){+.+.}, at: [] pipe_lock_nested fs/pipe.c:66 [inline] (&pipe->mutex/1){+.+.}, at: [] pipe_lock+0x56/0x70 fs/pipe.c:74 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (&pipe->mutex/1){+.+.}: check_prevs_add kernel/locking/lockdep.c:2020 [inline] validate_chain kernel/locking/lockdep.c:2469 [inline] __lock_acquire+0x328f/0x4620 kernel/locking/lockdep.c:3498 lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:4002 __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0x16f/0x1870 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 pipe_lock_nested fs/pipe.c:66 [inline] pipe_lock+0x56/0x70 fs/pipe.c:74 iter_file_splice_write+0x264/0xf50 fs/splice.c:715 do_splice_from fs/splice.c:867 [inline] do_splice fs/splice.c:1163 [inline] SYSC_splice fs/splice.c:1418 [inline] SyS_splice+0x7d5/0x1630 fs/splice.c:1398 entry_SYSCALL_64_fastpath+0x1f/0xbe -> #2 (sb_writers){.+.+}: percpu_down_read_preempt_disable include/linux/percpu-rwsem.h:35 [inline] percpu_down_read include/linux/percpu-rwsem.h:58 [inline] __sb_start_write+0x18f/0x290 fs/super.c:1340 sb_start_write include/linux/fs.h:1514 [inline] mnt_want_write+0x3f/0xb0 fs/namespace.c:386 filename_create+0x12b/0x520 fs/namei.c:3629 kern_path_create+0x33/0x40 fs/namei.c:3675 handle_create+0xc0/0x760 drivers/base/devtmpfs.c:202 -> #1 ((complete)&req.done){+.+.}: check_prevs_add kernel/locking/lockdep.c:2020 [inline] validate_chain kernel/locking/lockdep.c:2469 [inline] __lock_acquire+0x328f/0x4620 kernel/locking/lockdep.c:3498 lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:4002 complete_acquire include/linux/completion.h:39 [inline] __wait_for_common kernel/sched/completion.c:108 [inline] wait_for_common kernel/sched/completion.c:122 [inline] wait_for_completion+0xc8/0x770 kernel/sched/completion.c:143 devtmpfs_create_node+0x32b/0x4a0 drivers/base/devtmpfs.c:114 device_add+0x120f/0x1640 drivers/base/core.c:1824 device_create_groups_vargs+0x1f3/0x250 drivers/base/core.c:2430 device_create_vargs drivers/base/core.c:2470 [inline] device_create+0xda/0x110 drivers/base/core.c:2506 vcs_make_sysfs+0x35/0x60 drivers/tty/vt/vc_screen.c:628 vc_allocate+0x4b7/0x6b0 drivers/tty/vt/vt.c:795 con_install+0x52/0x440 drivers/tty/vt/vt.c:2876 tty_driver_install_tty drivers/tty/tty_io.c:1214 [inline] tty_init_dev+0xf6/0x4a0 drivers/tty/tty_io.c:1314 tty_open_by_driver drivers/tty/tty_io.c:1941 [inline] tty_open+0x60f/0xac0 drivers/tty/tty_io.c:1989 chrdev_open+0x257/0x730 fs/char_dev.c:416 do_dentry_open+0x67f/0xd70 fs/open.c:752 vfs_open+0x107/0x230 fs/open.c:866 do_last fs/namei.c:3388 [inline] path_openat+0x1157/0x3520 fs/namei.c:3528 do_filp_open+0x25b/0x3b0 fs/namei.c:3563 do_sys_open+0x502/0x6d0 fs/open.c:1059 SYSC_open fs/open.c:1077 [inline] SyS_open+0x2d/0x40 fs/open.c:1072 entry_SYSCALL_64_fastpath+0x1f/0xbe -> #0 (console_lock){+.+.}: check_prev_add+0x865/0x1520 kernel/locking/lockdep.c:1894 check_prevs_add kernel/locking/lockdep.c:2020 [inline] validate_chain kernel/locking/lockdep.c:2469 [inline] __lock_acquire+0x328f/0x4620 kernel/locking/lockdep.c:3498 lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:4002 console_lock+0x4b/0x80 kernel/printk/printk.c:2047 vcs_write+0x14d/0xca0 drivers/tty/vt/vc_screen.c:396 __vfs_write+0xef/0x970 fs/read_write.c:468 __kernel_write+0xfe/0x350 fs/read_write.c:490 write_pipe_buf+0x175/0x220 fs/splice.c:813 splice_from_pipe_feed fs/splice.c:518 [inline] __splice_from_pipe+0x343/0x750 fs/splice.c:642 splice_from_pipe+0x1e9/0x330 fs/splice.c:677 default_file_splice_write+0x40/0x90 fs/splice.c:825 do_splice_from fs/splice.c:867 [inline] do_splice fs/splice.c:1163 [inline] SYSC_splice fs/splice.c:1418 [inline] SyS_splice+0x7d5/0x1630 fs/splice.c:1398 do_syscall_64+0x26c/0x8c0 arch/x86/entry/common.c:287 return_from_SYSCALL_64+0x0/0x7a other info that might help us debug this: Chain exists of: console_lock --> sb_writers --> &pipe->mutex/1 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&pipe->mutex/1); lock(sb_writers); lock(&pipe->mutex/1); lock(console_lock); *** DEADLOCK *** 1 lock held by syz-executor0/5642: #0: (&pipe->mutex/1){+.+.}, at: [] pipe_lock_nested fs/pipe.c:66 [inline] #0: (&pipe->mutex/1){+.+.}, at: [] pipe_lock+0x56/0x70 fs/pipe.c:74 stack backtrace: CPU: 0 PID: 5642 Comm: syz-executor0 Not tainted 4.13.0-mm1+ #3 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:16 [inline] dump_stack+0x194/0x257 lib/dump_stack.c:52 print_circular_bug+0x503/0x710 kernel/locking/lockdep.c:1259 check_prev_add+0x865/0x1520 kernel/locking/lockdep.c:1894 check_prevs_add kernel/locking/lockdep.c:2020 [inline] validate_chain kernel/locking/lockdep.c:2469 [inline] __lock_acquire+0x328f/0x4620 kernel/locking/lockdep.c:3498 lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:4002 console_lock+0x4b/0x80 kernel/printk/printk.c:2047 vcs_write+0x14d/0xca0 drivers/tty/vt/vc_screen.c:396 __vfs_write+0xef/0x970 fs/read_write.c:468 __kernel_write+0xfe/0x350 fs/read_write.c:490 write_pipe_buf+0x175/0x220 fs/splice.c:813 splice_from_pipe_feed fs/splice.c:518 [inline] __splice_from_pipe+0x343/0x750 fs/splice.c:642 splice_from_pipe+0x1e9/0x330 fs/splice.c:677 default_file_splice_write+0x40/0x90 fs/splice.c:825 do_splice_from fs/splice.c:867 [inline] do_splice fs/splice.c:1163 [inline] SYSC_splice fs/splice.c:1418 [inline] SyS_splice+0x7d5/0x1630 fs/splice.c:1398 do_syscall_64+0x26c/0x8c0 arch/x86/entry/common.c:287 entry_SYSCALL64_slow_path+0x25/0x25 RIP: 0033:0x451e59 RSP: 002b:00007f9713a1dc08 EFLAGS: 00000216 ORIG_RAX: 0000000000000113 RAX: ffffffffffffffda RBX: 00000000007180b0 RCX: 0000000000451e59 RDX: 0000000000000017 RSI: 0000000000000000 RDI: 0000000000000006 RBP: 0000000000005c40 R08: 00000000fffffdff R09: 0000000000000000 R10: 0000000000800000 R11: 0000000000000216 R12: 00000000004bc0f0 R13: 00000000ffffffff R14: 0000000000000006 R15: 0000000000000000 rfkill: input handler disabled rfkill: input handler enabled Can not set IPV6_FL_F_REFLECT if flowlabel_consistency sysctl is enable netlink: 2 bytes leftover after parsing attributes in process `syz-executor1'. netlink: 2 bytes leftover after parsing attributes in process `syz-executor1'.