======================================================
WARNING: possible circular locking dependency detected
5.14.0-rc2-syzkaller #0 Not tainted
------------------------------------------------------
kworker/1:17/10474 is trying to acquire lock:
ffff8880108790b8 (&buf->lock){+.+.}-{3:3}, at: tty_buffer_flush+0x76/0x2b0 drivers/tty/tty_buffer.c:229
but task is already holding lock:
ffffffff8b96aac0 (console_lock){+.+.}-{0:0}, at: vc_SAK+0x10/0x310 drivers/tty/vt/vt_ioctl.c:980
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #2 (console_lock){+.+.}-{0:0}:
console_lock+0x49/0x80 kernel/printk/printk.c:2462
con_flush_chars drivers/tty/vt/vt.c:3325 [inline]
con_flush_chars+0x35/0x90 drivers/tty/vt/vt.c:3317
n_tty_write+0xbe5/0xfd0 drivers/tty/n_tty.c:2305
do_tty_write drivers/tty/tty_io.c:1038 [inline]
file_tty_write.constprop.0+0x526/0x910 drivers/tty/tty_io.c:1110
call_write_iter include/linux/fs.h:2114 [inline]
new_sync_write+0x426/0x650 fs/read_write.c:518
vfs_write+0x75a/0xa40 fs/read_write.c:605
ksys_write+0x12d/0x250 fs/read_write.c:658
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
-> #1 (&tty->termios_rwsem){++++}-{3:3}:
down_write+0x92/0x150 kernel/locking/rwsem.c:1406
n_tty_flush_buffer+0x1d/0x230 drivers/tty/n_tty.c:369
tty_buffer_flush+0x1f0/0x2b0 drivers/tty/tty_buffer.c:240
tty_ldisc_flush+0x66/0xe0 drivers/tty/tty_ldisc.c:400
tty_port_close_start.part.0+0x22c/0x550 drivers/tty/tty_port.c:602
tty_port_close_start drivers/tty/tty_port.c:646 [inline]
tty_port_close+0x46/0x170 drivers/tty/tty_port.c:639
uart_close+0x83/0x210 drivers/tty/serial/serial_core.c:1538
tty_release+0x45e/0x1200 drivers/tty/tty_io.c:1771
__fput+0x288/0x920 fs/file_table.c:280
task_work_run+0xdd/0x1a0 kernel/task_work.c:164
tracehook_notify_resume include/linux/tracehook.h:189 [inline]
exit_to_user_mode_loop kernel/entry/common.c:175 [inline]
exit_to_user_mode_prepare+0x27e/0x290 kernel/entry/common.c:209
__syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:302
do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x44/0xae
-> #0 (&buf->lock){+.+.}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3051 [inline]
check_prevs_add kernel/locking/lockdep.c:3174 [inline]
validate_chain kernel/locking/lockdep.c:3789 [inline]
__lock_acquire+0x2a07/0x54a0 kernel/locking/lockdep.c:5015
lock_acquire kernel/locking/lockdep.c:5625 [inline]
lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5590
__mutex_lock_common kernel/locking/mutex.c:959 [inline]
__mutex_lock+0x12a/0x10a0 kernel/locking/mutex.c:1104
tty_buffer_flush+0x76/0x2b0 drivers/tty/tty_buffer.c:229
tty_ldisc_flush+0x66/0xe0 drivers/tty/tty_ldisc.c:400
__do_SAK.part.0+0xd5/0x390 drivers/tty/tty_io.c:3046
__do_SAK+0x1b/0x30 drivers/tty/tty_io.c:3039
vc_SAK+0x7c/0x310 drivers/tty/vt/vt_ioctl.c:990
process_one_work+0x98d/0x1630 kernel/workqueue.c:2276
worker_thread+0x658/0x11f0 kernel/workqueue.c:2422
kthread+0x3e5/0x4d0 kernel/kthread.c:319
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
other info that might help us debug this:
Chain exists of:
&buf->lock --> &tty->termios_rwsem --> console_lock
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(console_lock);
lock(&tty->termios_rwsem);
lock(console_lock);
lock(&buf->lock);
*** DEADLOCK ***
4 locks held by kworker/1:17/10474:
#0: ffff888010864d38 ((wq_completion)events){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
#0: ffff888010864d38 ((wq_completion)events){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:620 [inline]
#0: ffff888010864d38 ((wq_completion)events){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
#0: ffff888010864d38 ((wq_completion)events){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:617 [inline]
#0: ffff888010864d38 ((wq_completion)events){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline]
#0: ffff888010864d38 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x871/0x1630 kernel/workqueue.c:2247
#1: ffffc90017fe7db0 ((work_completion)(&vc_cons[currcons].SAK_work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1630 kernel/workqueue.c:2251
#2: ffffffff8b96aac0 (console_lock){+.+.}-{0:0}, at: vc_SAK+0x10/0x310 drivers/tty/vt/vt_ioctl.c:980
#3: ffff888015c8b098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref drivers/tty/tty_ldisc.c:273 [inline]
#3: ffff888015c8b098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_flush+0x18/0xe0 drivers/tty/tty_ldisc.c:398
stack backtrace:
CPU: 1 PID: 10474 Comm: kworker/1:17 Not tainted 5.14.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events vc_SAK
Call Trace:
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:105
check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2131
check_prev_add kernel/locking/lockdep.c:3051 [inline]
check_prevs_add kernel/locking/lockdep.c:3174 [inline]
validate_chain kernel/locking/lockdep.c:3789 [inline]
__lock_acquire+0x2a07/0x54a0 kernel/locking/lockdep.c:5015
lock_acquire kernel/locking/lockdep.c:5625 [inline]
lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5590
__mutex_lock_common kernel/locking/mutex.c:959 [inline]
__mutex_lock+0x12a/0x10a0 kernel/locking/mutex.c:1104
tty_buffer_flush+0x76/0x2b0 drivers/tty/tty_buffer.c:229
tty_ldisc_flush+0x66/0xe0 drivers/tty/tty_ldisc.c:400
__do_SAK.part.0+0xd5/0x390 drivers/tty/tty_io.c:3046
__do_SAK+0x1b/0x30 drivers/tty/tty_io.c:3039
vc_SAK+0x7c/0x310 drivers/tty/vt/vt_ioctl.c:990
process_one_work+0x98d/0x1630 kernel/workqueue.c:2276
worker_thread+0x658/0x11f0 kernel/workqueue.c:2422
kthread+0x3e5/0x4d0 kernel/kthread.c:319
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295