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MIME-Version: 1.0 X-Received: by 2002:a6b:2bcd:: with SMTP id r196mr7593948ior.73.1561211705795; Sat, 22 Jun 2019 06:55:05 -0700 (PDT) Date: Sat, 22 Jun 2019 06:55:05 -0700 In-Reply-To: <0000000000009ad686058bc12956@google.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <00000000000024ae6f058be9ed51@google.com> Subject: Re: possible deadlock in console_trylock_spinning From: syzbot To: gregkh@linuxfoundation.org, jslaby@suse.com, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8"; format=flowed; delsp=yes Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org syzbot has found a reproducer for the following crash on: HEAD commit: abf02e29 Merge tag 'pm-5.2-rc6' of git://git.kernel.org/pu.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=11834c41a00000 kernel config: https://syzkaller.appspot.com/x/.config?x=28ec3437a5394ee0 dashboard link: https://syzkaller.appspot.com/bug?extid=fc1da0f1a577d15b64fc compiler: clang version 9.0.0 (/home/glider/llvm/clang 80fee25776c2fb61e74c1ecb1a523375c2500b69) syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1357add6a00000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1611ac89a00000 IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+fc1da0f1a577d15b64fc@syzkaller.appspotmail.com ====================================================== WARNING: possible circular locking dependency detected 5.2.0-rc5+ #4 Not tainted ------------------------------------------------------ syz-executor155/8057 is trying to acquire lock: 000000009bd46550 (console_owner){-.-.}, at: console_trylock_spinning+0x12f/0x390 kernel/printk/printk.c:1718 but task is already holding lock: 0000000056678186 (&(&port->lock)->rlock){-.-.}, at: pty_write+0xbd/0x190 drivers/tty/pty.c:120 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&(&port->lock)->rlock){-.-.}: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xa1/0xc0 kernel/locking/spinlock.c:159 tty_port_tty_get drivers/tty/tty_port.c:287 [inline] tty_port_default_wakeup+0x20/0xa0 drivers/tty/tty_port.c:47 tty_port_tty_wakeup+0x5a/0x70 drivers/tty/tty_port.c:387 uart_write_wakeup+0x48/0x60 drivers/tty/serial/serial_core.c:103 serial8250_tx_chars+0x623/0x830 drivers/tty/serial/8250/8250_port.c:1806 serial8250_handle_irq+0x255/0x390 drivers/tty/serial/8250/8250_port.c:1879 serial8250_default_handle_irq+0xc5/0x1d0 drivers/tty/serial/8250/8250_port.c:1895 serial8250_interrupt+0xad/0x190 drivers/tty/serial/8250/8250_core.c:125 __handle_irq_event_percpu+0x113/0x560 kernel/irq/handle.c:149 handle_irq_event_percpu kernel/irq/handle.c:189 [inline] handle_irq_event+0x10a/0x2f0 kernel/irq/handle.c:206 handle_edge_irq+0x29f/0xca0 kernel/irq/chip.c:822 generic_handle_irq_desc include/linux/irqdesc.h:156 [inline] handle_irq+0x3e/0x50 arch/x86/kernel/irq_64.c:34 do_IRQ+0xc4/0x1a0 arch/x86/kernel/irq.c:247 ret_from_intr+0x0/0x1e native_safe_halt+0xe/0x10 arch/x86/include/asm/irqflags.h:60 arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:571 default_idle_call kernel/sched/idle.c:94 [inline] cpuidle_idle_call kernel/sched/idle.c:154 [inline] do_idle+0x18a/0x760 kernel/sched/idle.c:263 cpu_startup_entry+0x25/0x30 kernel/sched/idle.c:354 start_secondary+0x425/0x4c0 arch/x86/kernel/smpboot.c:265 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:243 -> #1 (&port_lock_key){-.-.}: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xa1/0xc0 kernel/locking/spinlock.c:159 serial8250_console_write+0x1d1/0xba0 drivers/tty/serial/8250/8250_port.c:3245 univ8250_console_write+0x50/0x70 drivers/tty/serial/8250/8250_core.c:586 call_console_drivers kernel/printk/printk.c:1779 [inline] console_unlock+0x95f/0xf20 kernel/printk/printk.c:2463 vprintk_emit+0x239/0x3a0 kernel/printk/printk.c:1986 vprintk_default+0x28/0x30 kernel/printk/printk.c:2013 vprintk_func+0x158/0x170 kernel/printk/printk_safe.c:386 printk+0xc4/0x11d kernel/printk/printk.c:2046 register_console+0xa81/0xe30 kernel/printk/printk.c:2788 univ8250_console_init+0x4b/0x4d drivers/tty/serial/8250/8250_core.c:681 console_init+0x56/0x9c kernel/printk/printk.c:2874 start_kernel+0x49e/0x860 init/main.c:688 x86_64_start_reservations+0x18/0x2e arch/x86/kernel/head64.c:470 x86_64_start_kernel+0x7a/0x7d arch/x86/kernel/head64.c:451 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:243 -> #0 (console_owner){-.-.}: lock_acquire+0x158/0x250 kernel/locking/lockdep.c:4303 console_trylock_spinning+0x14f/0x390 kernel/printk/printk.c:1735 vprintk_emit+0x21c/0x3a0 kernel/printk/printk.c:1985 vprintk_default+0x28/0x30 kernel/printk/printk.c:2013 vprintk_func+0x158/0x170 kernel/printk/printk_safe.c:386 printk+0xc4/0x11d kernel/printk/printk.c:2046 fail_dump lib/fault-inject.c:45 [inline] should_fail+0x5c5/0x860 lib/fault-inject.c:144 __should_fail_alloc_page mm/page_alloc.c:3278 [inline] should_fail_alloc_page+0x55/0x60 mm/page_alloc.c:3315 prepare_alloc_pages+0x283/0x460 mm/page_alloc.c:4598 __alloc_pages_nodemask+0x11c/0x790 mm/page_alloc.c:4645 __alloc_pages include/linux/gfp.h:473 [inline] __alloc_pages_node include/linux/gfp.h:486 [inline] kmem_getpages+0x46/0x480 mm/slab.c:1373 cache_grow_begin+0x7e/0x2c0 mm/slab.c:2606 cache_alloc_refill+0x311/0x3f0 mm/slab.c:2978 ____cache_alloc mm/slab.c:3061 [inline] __do_cache_alloc mm/slab.c:3283 [inline] slab_alloc mm/slab.c:3318 [inline] __do_kmalloc mm/slab.c:3658 [inline] __kmalloc+0x2e5/0x310 mm/slab.c:3669 kmalloc include/linux/slab.h:552 [inline] tty_buffer_alloc drivers/tty/tty_buffer.c:175 [inline] __tty_buffer_request_room+0x1ef/0x560 drivers/tty/tty_buffer.c:273 tty_insert_flip_string_fixed_flag+0xa4/0x2b0 drivers/tty/tty_buffer.c:318 tty_insert_flip_string include/linux/tty_flip.h:37 [inline] pty_write+0xe2/0x190 drivers/tty/pty.c:122 tty_put_char+0x115/0x180 drivers/tty/tty_io.c:3031 __process_echoes+0x19d/0x920 drivers/tty/n_tty.c:746 flush_echoes drivers/tty/n_tty.c:829 [inline] __receive_buf drivers/tty/n_tty.c:1648 [inline] n_tty_receive_buf_common+0x297f/0x3080 drivers/tty/n_tty.c:1742 n_tty_receive_buf+0x30/0x40 drivers/tty/n_tty.c:1771 tiocsti drivers/tty/tty_io.c:2195 [inline] tty_ioctl+0xd63/0x15d0 drivers/tty/tty_io.c:2571 do_vfs_ioctl+0x7d4/0x1890 fs/ioctl.c:46 ksys_ioctl fs/ioctl.c:713 [inline] __do_sys_ioctl fs/ioctl.c:720 [inline] __se_sys_ioctl fs/ioctl.c:718 [inline] __x64_sys_ioctl+0xe3/0x120 fs/ioctl.c:718 do_syscall_64+0xfe/0x140 arch/x86/entry/common.c:301 entry_SYSCALL_64_after_hwframe+0x49/0xbe other info that might help us debug this: Chain exists of: console_owner --> &port_lock_key --> &(&port->lock)->rlock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&(&port->lock)->rlock); lock(&port_lock_key); lock(&(&port->lock)->rlock); lock(console_owner); *** DEADLOCK *** 4 locks held by syz-executor155/8057: #0: 00000000537d947b (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:272 #1: 00000000edca1b1e (&o_tty->termios_rwsem/1){++++}, at: n_tty_receive_buf_common+0x8b/0x3080 drivers/tty/n_tty.c:1705 #2: 00000000e4a6cb09 (&ldata->output_lock){+.+.}, at: flush_echoes drivers/tty/n_tty.c:827 [inline] #2: 00000000e4a6cb09 (&ldata->output_lock){+.+.}, at: __receive_buf drivers/tty/n_tty.c:1648 [inline] #2: 00000000e4a6cb09 (&ldata->output_lock){+.+.}, at: n_tty_receive_buf_common+0x2940/0x3080 drivers/tty/n_tty.c:1742 #3: 0000000056678186 (&(&port->lock)->rlock){-.-.}, at: pty_write+0xbd/0x190 drivers/tty/pty.c:120 stack backtrace: CPU: 1 PID: 8057 Comm: syz-executor155 Not tainted 5.2.0-rc5+ #4 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1d8/0x2f8 lib/dump_stack.c:113 print_circular_bug+0xd34/0xf20 kernel/locking/lockdep.c:1564 check_prev_add kernel/locking/lockdep.c:2310 [inline] check_prevs_add kernel/locking/lockdep.c:2418 [inline] validate_chain+0x59d0/0x84f0 kernel/locking/lockdep.c:2800 __lock_acquire+0xcf7/0x1a40 kernel/locking/lockdep.c:3793 lock_acquire+0x158/0x250 kernel/locking/lockdep.c:4303 console_trylock_spinning+0x14f/0x390 kernel/printk/printk.c:1735 vprintk_emit+0x21c/0x3a0 kernel/printk/printk.c:1985 vprintk_default+0x28/0x30 kernel/printk/printk.c:2013 vprintk_func+0x158/0x170 kernel/printk/printk_safe.c:386 printk+0xc4/0x11d kernel/printk/printk.c:2046 fail_dump lib/fault-inject.c:45 [inline] should_fail+0x5c5/0x860 lib/fault-inject.c:144 __should_fail_alloc_page mm/page_alloc.c:3278 [inline] should_fail_alloc_page+0x55/0x60 mm/page_alloc.c:3315 prepare_alloc_pages+0x283/0x460 mm/page_alloc.c:4598 __alloc_pages_nodemask+0x11c/0x790 mm/page_alloc.c:4645 __alloc_pages include/linux/gfp.h:473 [inline] __alloc_pages_node include/linux/gfp.h:486 [inline] kmem_getpages+0x46/0x480 mm/slab.c:1373 cache_grow_begin+0x7e/0x2c0 mm/slab.c:2606 cache_alloc_refill+0x311/0x3f0 mm/slab.c:2978 ____cache_alloc mm/slab.c:3061 [inline] __do_cache_alloc mm/slab.c:3283 [inline] slab_alloc mm/slab.c:3318 [inline] __do_kmalloc mm/slab.c:3658 [inline] __kmalloc+0x2e5/0x310 mm/slab.c:3669 kmalloc include/linux/slab.h:552 [inline] tty_buffer_alloc drivers/tty/tty_buffer.c:175 [inline] __tty_buffer_request_room+0x1ef/0x560 drivers/tty/tty_buffer.c:273 tty_insert_flip_string_fixed_flag+0xa4/0x2b0 drivers/tty/tty_buffer.c:318 tty_insert_flip_string include/linux/tty_flip.h:37 [inline] pty_write+0xe2/0x190 drivers/tty/pty.c:122 tty_put_char+0x115/0x180 drivers/tty/tty_io.c:3031 __process_echoes+0x19d/0x920 drivers/tty/n_tty.c:746 flush_echoes drivers/tty/n_tty.c:829 [inline] __receive_buf drivers/tty/n_tty.c:1648 [inline] n_tty_receive_buf_common+0x297f/0x3080 drivers/tty/n_tty.c:1742 n_tty_receive_buf+0x30/0x40 drivers/tty/n_tty.c:1771 tiocsti drivers/tty/tty_io.c:2195 [inline] tty_ioctl+0xd63/0x15d0 drivers/tty/tty_io.c:2571 do_vfs_ioctl+0x7d4/0x1890 fs/ioctl.c:46 ksys_ioctl fs/ioctl.c:713 [inline] __do_sys_ioctl fs/ioctl.c:720 [inline] __se_sys_ioctl fs/ioctl.c:718 [inline] __x64_sys_ioctl+0xe3/0x120 fs/ioctl.c:718 do_syscall_64+0xfe/0x140 arch/x86/entry/common.c:301 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x441439 Code: e8 8c e8 ff ff 48 83 c4 18 c3 0f 1f 80 00 00 00 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 0f 83 eb 09 fc ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007ffeff301068 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000441439 RDX: 0000000020000040 RSI: 0000000000005412 RDI: 0000000000000004 RBP: 00007ffeff301080 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: ffffffffffffffff R13: 0000000000000005 R14: 0000000000000000 R15: 0000000000000000