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Message-ID: <CACT4Y+aFArPDsyvpNko+_eZi=1UTd2NxfejiyawRA0aKScWmJA@mail.gmail.com>
Date:   Mon, 20 Jun 2022 10:16:40 +0200
From:   Dmitry Vyukov <dvyukov@...gle.com>
To:     Sergey Senozhatsky <senozhatsky@...omium.org>
Cc:     syzbot <syzbot+3cc1054e15babd5f4cd2@...kaller.appspotmail.com>,
        akpm@...ux-foundation.org, glider@...gle.com,
        gregkh@...uxfoundation.org, jirislaby@...nel.org,
        john.ogness@...utronix.de, linux-kernel@...r.kernel.org,
        npiggin@...il.com, pmladek@...e.com, rdunlap@...radead.org,
        rostedt@...dmis.org, swboyd@...omium.org,
        syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] possible deadlock in console_lock_spinning_enable (2)

On Mon, 20 Jun 2022 at 07:44, Sergey Senozhatsky
<senozhatsky@...omium.org> wrote:
>
> On (22/06/18 20:47), syzbot wrote:
> > syzbot suspects this issue was fixed by commit:
> >
> > commit faebd693c59387b7b765fab64b543855e15a91b4
> > Author: John Ogness <john.ogness@...utronix.de>
> > Date:   Thu Apr 21 21:22:36 2022 +0000
> >
> >     printk: rename cpulock functions
>
> I'd rather guess that it was console kthread patch that fixed the problem.

Hi Sergey,

Do you mean this commit:

author: John Ogness 2022-04-21 23:28:48 +0206
printk: add kthread console printers

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=09c5ba0aa2fcfdadb17d045c3ee6f86d69270df7

?

> And the problem here is slab fault injection, which triggers printk
> under port->lock, which is a reverse locking chain: we usually do
> printk, grab console owner and then call into console driver and take
> the port->lock.
>
> [  302.408357][ T6160] isofs_fill_super: get root inode failed
> [  302.447591][ T6181] FAULT_INJECTION: forcing a failure.
> [  302.447591][ T6181] name failslab, interval 1, probability 0, space 0, times 0
> [  302.447761][ T6181]
> [  302.447764][ T6181] ======================================================
> [  302.447767][ T6181] WARNING: possible circular locking dependency detected
> [  302.447770][ T6181] 5.18.0-rc7-syzkaller-00048-gf993aed406ea #0 Not tainted
> [  302.447776][ T6181] ------------------------------------------------------
> [  302.447779][ T6181] syz-executor.5/6181 is trying to acquire lock:
> [  302.447784][ T6181] ffffffff8cb0f4a0 (console_owner){....}-{0:0}, at: console_lock_spinning_enable+0x2d/0x60
> [  302.447841][ T6181]
> [  302.447841][ T6181] but task is already holding lock:
> [  302.447843][ T6181] ffff88801b67f958 (&port->lock){-.-.}-{2:2}, at: pty_write+0xc5/0x170
> [  302.447874][ T6181]
> [  302.447874][ T6181] which lock already depends on the new lock.
> [  302.447874][ T6181]
> [  302.447877][ T6181]
> [  302.447877][ T6181] the existing dependency chain (in reverse order) is:
> [  302.447880][ T6181]
> [  302.447880][ T6181] -> #2 (&port->lock){-.-.}-{2:2}:
> [  302.447892][ T6181]        lock_acquire+0x1a7/0x400
> [  302.447902][ T6181]        _raw_spin_lock_irqsave+0xd1/0x120
> [  302.447911][ T6181]        tty_port_default_wakeup+0x21/0x100
> [  302.447921][ T6181]        serial8250_tx_chars+0x60e/0x810
> [  302.447962][ T6181]        serial8250_handle_irq+0x32f/0x410
> [  302.447972][ T6181]        serial8250_default_handle_irq+0xaf/0x190
> [  302.447980][ T6181]        serial8250_interrupt+0xa3/0x1e0
> [  302.447990][ T6181]        __handle_irq_event_percpu+0x200/0x620
> [  302.448001][ T6181]        handle_irq_event+0x83/0x1e0
> [  302.448010][ T6181]        handle_edge_irq+0x245/0xbe0
> [  302.448017][ T6181]        __common_interrupt+0xce/0x1e0
> [  302.448056][ T6181]        common_interrupt+0x9f/0xc0
> [  302.448065][ T6181]        asm_common_interrupt+0x1e/0x40
> [  302.448074][ T6181]        acpi_idle_enter+0x42d/0x790
> [  302.448112][ T6181]        cpuidle_enter_state+0x517/0xed0
> [  302.448149][ T6181]        cpuidle_enter+0x59/0x90
> [  302.448157][ T6181]        do_idle+0x3d2/0x640
> [  302.448177][ T6181]        cpu_startup_entry+0x15/0x20
> [  302.448186][ T6181]        rest_init+0x24f/0x270
> [  302.448194][ T6181]        start_kernel+0x0/0x56e
> [  302.448224][ T6181]        start_kernel+0x4bf/0x56e
> [  302.448232][ T6181]        secondary_startup_64_no_verify+0xc4/0xcb
> [  302.448247][ T6181]
> [  302.448247][ T6181] -> #1 (&port_lock_key){-.-.}-{2:2}:
> [  302.448262][ T6181]        lock_acquire+0x1a7/0x400
> [  302.448275][ T6181]        _raw_spin_lock_irqsave+0xd1/0x120
> [  302.448289][ T6181]        serial8250_console_write+0x19c/0xf60
> [  302.448304][ T6181]        console_unlock+0xa98/0x1150
> [  302.448319][ T6181]        vprintk_emit+0xd1/0x1e0
> [  302.448334][ T6181]        _printk+0xcf/0x10f
> [  302.448349][ T6181]        register_console+0x6e2/0x9c0
> [  302.448362][ T6181]        univ8250_console_init+0x41/0x43
> [  302.448390][ T6181]        console_init+0x5d/0xa8
> [  302.448406][ T6181]        start_kernel+0x328/0x56e
> [  302.448421][ T6181]        secondary_startup_64_no_verify+0xc4/0xcb
> [  302.448440][ T6181]
> [  302.448440][ T6181] -> #0 (console_owner){....}-{0:0}:
> [  302.448462][ T6181]        validate_chain+0x185c/0x65c0
> [  302.448479][ T6181]        __lock_acquire+0x129a/0x1f80
> [  302.448492][ T6181]        lock_acquire+0x1a7/0x400
> [  302.448500][ T6181]        console_lock_spinning_enable+0x52/0x60
> [  302.448509][ T6181]        console_unlock+0x7f4/0x1150
> [  302.448518][ T6181]        vprintk_emit+0xd1/0x1e0
> [  302.448526][ T6181]        _printk+0xcf/0x10f
> [  302.448534][ T6181]        should_fail+0x366/0x4b0
> [  302.448544][ T6181]        should_failslab+0x5/0x20
> [  302.448554][ T6181]        __kmalloc+0x8b/0x370
> [  302.448562][ T6181]        __tty_buffer_request_room+0x1f0/0x540
> [  302.448572][ T6181]        tty_insert_flip_string_fixed_flag+0x91/0x2c0
> [  302.448582][ T6181]        pty_write+0xe9/0x170
> [  302.448589][ T6181]        n_tty_write+0x665/0x13b0
> [  302.448597][ T6181]        file_tty_write+0x5a5/0x960
> [  302.448605][ T6181]        vfs_write+0xa22/0xd40
> [  302.448613][ T6181]        ksys_write+0x19b/0x2c0
> [  302.448620][ T6181]        do_syscall_64+0x2b/0x70
> [  302.448628][ T6181]        entry_SYSCALL_64_after_hwframe+0x44/0xae
> [  302.448637][ T6181]
> [  302.448637][ T6181] other info that might help us debug this:
> [  302.448637][ T6181]
> [  302.448640][ T6181] Chain exists of:
> [  302.448640][ T6181]   console_owner --> &port_lock_key --> &port->lock
> [  302.448640][ T6181]
> [  302.448653][ T6181]  Possible unsafe locking scenario:
> [  302.448653][ T6181]
> [  302.448655][ T6181]        CPU0                    CPU1
> [  302.448657][ T6181]        ----                    ----
> [  302.448659][ T6181]   lock(&port->lock);
> [  302.448664][ T6181]                                lock(&port_lock_key);
> [  302.448670][ T6181]                                lock(&port->lock);
> [  302.448675][ T6181]   lock(console_owner);
> [  302.448680][ T6181]
> [  302.448680][ T6181]  *** DEADLOCK ***
> [  302.448680][ T6181]
> [  302.448682][ T6181] 6 locks held by syz-executor.5/6181:
> [  302.448687][ T6181]  #0: ffff88804d6c2098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70
> [  302.448709][ T6181]  #1: ffff88804d6c2130 (&tty->atomic_write_lock){+.+.}-{3:3}, at: file_tty_write+0x26e/0x960
> [  302.448731][ T6181]  #2: ffff88804d6c22e8 (&tty->termios_rwsem){++++}-{3:3}, at: n_tty_write+0x244/0x13b0
> [  302.448752][ T6181]  #3: ffffc90010d81378 (&ldata->output_lock){+.+.}-{3:3}, at: n_tty_write+0x61a/0x13b0
> [  302.448774][ T6181]  #4: ffff88801b67f958 (&port->lock){-.-.}-{2:2}, at: pty_write+0xc5/0x170
> [  302.448793][ T6181]  #5: ffffffff8c9f71a0 (console_lock){+.+.}-{0:0}, at: vprintk_emit+0xb8/0x1e0
> [  302.448813][ T6181]
> [  302.448813][ T6181] stack backtrace:
> [  302.448817][ T6181] CPU: 0 PID: 6181 Comm: syz-executor.5 Not tainted 5.18.0-rc7-syzkaller-00048-gf993aed406ea #0
> [  302.448827][ T6181] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> [  302.448832][ T6181] Call Trace:
> [  302.448836][ T6181]  <TASK>
> [  302.448840][ T6181]  dump_stack_lvl+0x1e3/0x2cb
> [  302.448853][ T6181]  ? bfq_pos_tree_add_move+0x436/0x436
> [  302.448866][ T6181]  ? print_circular_bug+0x13e/0x1c0
> [  302.448876][ T6181]  check_noncircular+0x2f7/0x3b0
> [  302.448887][ T6181]  ? add_chain_block+0x850/0x850
> [  302.448897][ T6181]  ? lockdep_lock+0x11d/0x2a0
> [  302.448910][ T6181]  validate_chain+0x185c/0x65c0
> [  302.448924][ T6181]  ? vsnprintf+0x1ce0/0x1ce0
> [  302.448934][ T6181]  ? reacquire_held_locks+0x680/0x680
> [  302.448943][ T6181]  ? memset+0x1f/0x40
> [  302.448980][ T6181]  ? vsnprintf+0x1fa/0x1ce0
> [  302.448990][ T6181]  ? memcpy+0x3c/0x60
> [  302.448999][ T6181]  ? vsnprintf+0x1c02/0x1ce0
> [  302.449009][ T6181]  ? reacquire_held_locks+0x680/0x680
> [  302.449030][ T6181]  ? sprintf+0xd6/0x120
> [  302.449040][ T6181]  ? _prb_read_valid+0xbb9/0xbd0
> [  302.449051][ T6181]  ? mark_lock+0x98/0x350
> [  302.449061][ T6181]  __lock_acquire+0x129a/0x1f80
> [  302.449081][ T6181]  lock_acquire+0x1a7/0x400
> [  302.449094][ T6181]  ? console_lock_spinning_enable+0x2d/0x60
> [  302.449113][ T6181]  ? read_lock_is_recursive+0x10/0x10
> [  302.449130][ T6181]  ? console_lock_spinning_enable+0x2d/0x60
> [  302.449147][ T6181]  ? __lock_acquire+0x1f80/0x1f80
> [  302.449162][ T6181]  ? do_raw_spin_lock+0x148/0x360
> [  302.449183][ T6181]  ? _raw_spin_unlock+0x40/0x40
> [  302.449200][ T6181]  console_lock_spinning_enable+0x52/0x60
> [  302.449217][ T6181]  ? console_lock_spinning_enable+0x2d/0x60
> [  302.449238][ T6181]  console_unlock+0x7f4/0x1150
> [  302.449257][ T6181]  ? vprintk_emit+0xb8/0x1e0
> [  302.449273][ T6181]  ? console_trylock_spinning+0x450/0x450
> [  302.449288][ T6181]  ? vprintk_emit+0xb8/0x1e0
> [  302.449297][ T6181]  ? console_trylock+0x70/0x70
> [  302.449305][ T6181]  ? register_lock_class+0xfe/0x9d0
> [  302.449315][ T6181]  ? reacquire_held_locks+0x680/0x680
> [  302.449326][ T6181]  ? register_lock_class+0xfe/0x9d0
> [  302.449336][ T6181]  ? is_dynamic_key+0x1f0/0x1f0
> [  302.449345][ T6181]  vprintk_emit+0xd1/0x1e0
> [  302.449355][ T6181]  _printk+0xcf/0x10f
> [  302.449365][ T6181]  ? panic+0x76e/0x76e
> [  302.449382][ T6181]  should_fail+0x366/0x4b0
> [  302.449401][ T6181]  ? __tty_buffer_request_room+0x1f0/0x540
> [  302.449427][ T6181]  should_failslab+0x5/0x20
> [  302.449446][ T6181]  __kmalloc+0x8b/0x370
> [  302.449465][ T6181]  __tty_buffer_request_room+0x1f0/0x540
> [  302.449478][ T6181]  tty_insert_flip_string_fixed_flag+0x91/0x2c0
> [  302.449491][ T6181]  ? _raw_spin_unlock_irqrestore+0xd9/0x130
> [  302.449507][ T6181]  ? _raw_spin_unlock+0x40/0x40
> [  302.449524][ T6181]  pty_write+0xe9/0x170
> [  302.449540][ T6181]  n_tty_write+0x665/0x13b0
> [  302.449559][ T6181]  ? _copy_from_iter+0x429/0xec0
> [  302.449584][ T6181]  ? n_tty_read+0x1c90/0x1c90
> [  302.449599][ T6181]  ? wait_woken+0x1b0/0x1b0
> [  302.449621][ T6181]  ? check_heap_object+0x13c/0x310
> [  302.449633][ T6181]  ? 0xffffffff81000000
> [  302.449639][ T6181]  ? __check_object_size+0x15a/0x210
> [  302.449650][ T6181]  file_tty_write+0x5a5/0x960
> [  302.449660][ T6181]  ? n_tty_read+0x1c90/0x1c90
> [  302.449671][ T6181]  vfs_write+0xa22/0xd40
> [  302.449679][ T6181]  ? __lock_acquire+0x1f80/0x1f80
> [  302.449689][ T6181]  ? file_end_write+0x230/0x230
> [  302.449700][ T6181]  ? __fget_files+0x3d0/0x440
> [  302.449710][ T6181]  ? __fdget_pos+0x1d7/0x2e0
> [  302.449718][ T6181]  ? ksys_write+0x77/0x2c0
> [  302.449727][ T6181]  ksys_write+0x19b/0x2c0
> [  302.449736][ T6181]  ? print_irqtrace_events+0x220/0x220
> [  302.449745][ T6181]  ? __ia32_sys_read+0x80/0x80
> [  302.449754][ T6181]  ? syscall_enter_from_user_mode+0x2e/0x1a0
> [  302.449765][ T6181]  ? syscall_enter_from_user_mode+0x2e/0x1a0
> [  302.449775][ T6181]  do_syscall_64+0x2b/0x70
> [  302.449783][ T6181]  entry_SYSCALL_64_after_hwframe+0x44/0xae
> [  302.449793][ T6181] RIP: 0033:0x7f2630c890e9
> [  302.449801][ T6181] Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
> [  302.449809][ T6181] RSP: 002b:00007f2631df9168 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
> [  302.449819][ T6181] RAX: ffffffffffffffda RBX: 00007f2630d9bf60 RCX: 00007f2630c890e9
> [  302.449827][ T6181] RDX: 000000000000ff2e RSI: 00000000200000c0 RDI: 0000000000000004
> [  302.449833][ T6181] RBP: 00007f2631df91d0 R08: 0000000000000000 R09: 0000000000000000
> [  302.449839][ T6181] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
> [  302.449845][ T6181] R13: 00007ffe692c072f R14: 00007f2631df9300 R15: 0000000000022000
> [  302.449856][ T6181]  </TASK>
> [  303.425580][ T6181] CPU: 0 PID: 6181 Comm: syz-executor.5 Not tainted 5.18.0-rc7-syzkaller-00048-gf993aed406ea #0
> [  303.435966][ T6181] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> [  303.445999][ T6181] Call Trace:
> [  303.449261][ T6181]  <TASK>
> [  303.452173][ T6181]  dump_stack_lvl+0x1e3/0x2cb
> [  303.456838][ T6181]  ? bfq_pos_tree_add_move+0x436/0x436
> [  303.462275][ T6181]  ? panic+0x76e/0x76e
> [  303.466333][ T6181]  should_fail+0x384/0x4b0
> [  303.470756][ T6181]  ? __tty_buffer_request_room+0x1f0/0x540
> [  303.476557][ T6181]  should_failslab+0x5/0x20
> [  303.481042][ T6181]  __kmalloc+0x8b/0x370
> [  303.485179][ T6181]  __tty_buffer_request_room+0x1f0/0x540
> [  303.490801][ T6181]  tty_insert_flip_string_fixed_flag+0x91/0x2c0
> [  303.497028][ T6181]  ? _raw_spin_unlock_irqrestore+0xd9/0x130
> [  303.502902][ T6181]  ? _raw_spin_unlock+0x40/0x40
> [  303.507731][ T6181]  pty_write+0xe9/0x170
> [  303.511866][ T6181]  n_tty_write+0x665/0x13b0
> [  303.516353][ T6181]  ? _copy_from_iter+0x429/0xec0
> [  303.521277][ T6181]  ? n_tty_read+0x1c90/0x1c90
> [  303.525944][ T6181]  ? wait_woken+0x1b0/0x1b0
> [  303.530439][ T6181]  ? check_heap_object+0x13c/0x310
> [  303.535546][ T6181]  ? 0xffffffff81000000
> [  303.539687][ T6181]  ? __check_object_size+0x15a/0x210
> [  303.544962][ T6181]  file_tty_write+0x5a5/0x960
> [  303.549632][ T6181]  ? n_tty_read+0x1c90/0x1c90
> [  303.554294][ T6181]  vfs_write+0xa22/0xd40
> [  303.558519][ T6181]  ? __lock_acquire+0x1f80/0x1f80
> [  303.563524][ T6181]  ? file_end_write+0x230/0x230
> [  303.568357][ T6181]  ? __fget_files+0x3d0/0x440
> [  303.573016][ T6181]  ? __fdget_pos+0x1d7/0x2e0
> [  303.577588][ T6181]  ? ksys_write+0x77/0x2c0
> [  303.581995][ T6181]  ksys_write+0x19b/0x2c0
> [  303.586311][ T6181]  ? print_irqtrace_events+0x220/0x220
> [  303.591763][ T6181]  ? __ia32_sys_read+0x80/0x80
> [  303.596506][ T6181]  ? syscall_enter_from_user_mode+0x2e/0x1a0
> [  303.602470][ T6181]  ? syscall_enter_from_user_mode+0x2e/0x1a0
> [  303.608438][ T6181]  do_syscall_64+0x2b/0x70
> [  303.612834][ T6181]  entry_SYSCALL_64_after_hwframe+0x44/0xae
> [  303.618709][ T6181] RIP: 0033:0x7f2630c890e9
> [  303.623108][ T6181] Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
> [  303.642692][ T6181] RSP: 002b:00007f2631df9168 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
>
> --
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