Hello, syzbot found the following issue on: HEAD commit: 5a77386984b5 Merge tag 'drm-fixes-2022-09-30-1' of git://a.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=132b8504880000 kernel config: https://syzkaller.appspot.com/x/.config?x=a1992c90769e07 dashboard link: https://syzkaller.appspot.com/bug?extid=223c7461c58c58a4cb10 compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 Unfortunately, I don't have any reproducer for this issue yet. IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+223c7461c58c58a4cb10@xxxxxxxxxxxxxxxxxxxxxxxxx ====================================================== WARNING: possible circular locking dependency detected 6.0.0-rc7-syzkaller-00162-g5a77386984b5 #0 Not tainted ------------------------------------------------------ syz-executor.0/4926 is trying to acquire lock: ffffffff8c0be788 (zonelist_update_seq.seqcount){...-}-{0:0}, at: __alloc_pages+0x43d/0x510 mm/page_alloc.c:5562 but task is already holding lock: ffff88802624c958 (&port->lock){-.-.}-{2:2}, at: tty_insert_flip_string_and_push_buffer+0x2b/0x160 drivers/tty/tty_buffer.c:628 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (&port->lock){-.-.}-{2:2}: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:162 tty_port_tty_get+0x1f/0x100 drivers/tty/tty_port.c:327 tty_port_default_wakeup+0x11/0x40 drivers/tty/tty_port.c:68 serial8250_tx_chars+0x4f6/0xd90 drivers/tty/serial/8250/8250_port.c:1851 serial8250_handle_irq.part.0+0x440/0x820 drivers/tty/serial/8250/8250_port.c:1938 serial8250_handle_irq drivers/tty/serial/8250/8250_port.c:1911 [inline] serial8250_default_handle_irq+0xb2/0x220 drivers/tty/serial/8250/8250_port.c:1958 serial8250_interrupt+0xf8/0x200 drivers/tty/serial/8250/8250_core.c:126 __handle_irq_event_percpu+0x227/0x870 kernel/irq/handle.c:158 handle_irq_event_percpu kernel/irq/handle.c:193 [inline] handle_irq_event+0xa7/0x1e0 kernel/irq/handle.c:210 handle_edge_irq+0x25f/0xd00 kernel/irq/chip.c:819 generic_handle_irq_desc include/linux/irqdesc.h:158 [inline] handle_irq arch/x86/kernel/irq.c:231 [inline] __common_interrupt+0x9d/0x210 arch/x86/kernel/irq.c:250 common_interrupt+0xa4/0xc0 arch/x86/kernel/irq.c:240 asm_common_interrupt+0x22/0x40 arch/x86/include/asm/idtentry.h:640 native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline] arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline] default_idle+0xb/0x10 arch/x86/kernel/process.c:730 default_idle_call+0x80/0xc0 kernel/sched/idle.c:109 cpuidle_idle_call kernel/sched/idle.c:191 [inline] do_idle+0x401/0x590 kernel/sched/idle.c:303 cpu_startup_entry+0x14/0x20 kernel/sched/idle.c:400 start_secondary+0x21d/0x2b0 arch/x86/kernel/smpboot.c:262 secondary_startup_64_no_verify+0xce/0xdb -> #2 (&port_lock_key){-.-.}-{2:2}: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:162 serial8250_console_write+0x975/0xfe0 drivers/tty/serial/8250/8250_port.c:3380 call_console_driver kernel/printk/printk.c:1945 [inline] console_emit_next_record.constprop.0+0x3de/0x840 kernel/printk/printk.c:2732 console_flush_all kernel/printk/printk.c:2794 [inline] console_unlock+0x37a/0x5a0 kernel/printk/printk.c:2861 vprintk_emit+0x1b9/0x5f0 kernel/printk/printk.c:2271 vprintk+0x80/0x90 kernel/printk/printk_safe.c:50 _printk+0xba/0xed kernel/printk/printk.c:2292 register_console kernel/printk/printk.c:3212 [inline] register_console+0x482/0x840 kernel/printk/printk.c:3104 univ8250_console_init+0x3a/0x46 drivers/tty/serial/8250/8250_core.c:681 console_init+0x3b7/0x57e kernel/printk/printk.c:3308 start_kernel+0x2fa/0x48f init/main.c:1066 secondary_startup_64_no_verify+0xce/0xdb -> #1 (console_owner){-...}-{0:0}: console_lock_spinning_enable kernel/printk/printk.c:1808 [inline] console_emit_next_record.constprop.0+0x2dd/0x840 kernel/printk/printk.c:2729 console_flush_all kernel/printk/printk.c:2794 [inline] console_unlock+0x37a/0x5a0 kernel/printk/printk.c:2861 vprintk_emit+0x1b9/0x5f0 kernel/printk/printk.c:2271 vprintk+0x80/0x90 kernel/printk/printk_safe.c:50 _printk+0xba/0xed kernel/printk/printk.c:2292 build_zonelists.cold+0xe5/0x11f mm/page_alloc.c:6471 __build_all_zonelists+0x111/0x180 mm/page_alloc.c:6584 build_all_zonelists_init+0x2f/0x104 mm/page_alloc.c:6609 build_all_zonelists+0x11f/0x140 mm/page_alloc.c:6642 start_kernel+0xb9/0x48f init/main.c:960 secondary_startup_64_no_verify+0xce/0xdb -> #0 (zonelist_update_seq.seqcount){...-}-{0:0}: check_prev_add kernel/locking/lockdep.c:3095 [inline] check_prevs_add kernel/locking/lockdep.c:3214 [inline] validate_chain kernel/locking/lockdep.c:3829 [inline] __lock_acquire+0x2a43/0x56d0 kernel/locking/lockdep.c:5053 lock_acquire kernel/locking/lockdep.c:5666 [inline] lock_acquire+0x1ab/0x570 kernel/locking/lockdep.c:5631 seqcount_lockdep_reader_access include/linux/seqlock.h:102 [inline] read_seqbegin include/linux/seqlock.h:836 [inline] zonelist_iter_begin mm/page_alloc.c:4722 [inline] __alloc_pages_slowpath.constprop.0+0x1a5/0x2300 mm/page_alloc.c:5044 __alloc_pages+0x43d/0x510 mm/page_alloc.c:5562 __alloc_pages_node include/linux/gfp.h:243 [inline] kmem_getpages mm/slab.c:1363 [inline] cache_grow_begin+0x75/0x360 mm/slab.c:2569 cache_alloc_refill+0x27f/0x380 mm/slab.c:2942 ____cache_alloc mm/slab.c:3018 [inline] ____cache_alloc mm/slab.c:3001 [inline] __do_cache_alloc mm/slab.c:3246 [inline] slab_alloc mm/slab.c:3287 [inline] __do_kmalloc mm/slab.c:3684 [inline] __kmalloc+0x3a1/0x4a0 mm/slab.c:3695 kmalloc include/linux/slab.h:605 [inline] tty_buffer_alloc+0x27b/0x2f0 drivers/tty/tty_buffer.c:180 __tty_buffer_request_room+0x15f/0x2b0 drivers/tty/tty_buffer.c:278 tty_insert_flip_string_fixed_flag+0x8c/0x250 drivers/tty/tty_buffer.c:327 tty_insert_flip_string include/linux/tty_flip.h:41 [inline] tty_insert_flip_string_and_push_buffer+0x3e/0x160 drivers/tty/tty_buffer.c:629 pty_write+0xd6/0x100 drivers/tty/pty.c:118 process_output_block drivers/tty/n_tty.c:586 [inline] n_tty_write+0x4ca/0xfd0 drivers/tty/n_tty.c:2350 do_tty_write drivers/tty/tty_io.c:1024 [inline] file_tty_write.constprop.0+0x499/0x8f0 drivers/tty/tty_io.c:1095 call_write_iter include/linux/fs.h:2187 [inline] new_sync_write fs/read_write.c:491 [inline] vfs_write+0x9e9/0xdd0 fs/read_write.c:584 ksys_write+0x127/0x250 fs/read_write.c:637 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+0x63/0xcd other info that might help us debug this: Chain exists of: zonelist_update_seq.seqcount --> &port_lock_key --> &port->lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&port->lock); lock(&port_lock_key); lock(&port->lock); lock(zonelist_update_seq.seqcount); *** DEADLOCK *** 5 locks held by syz-executor.0/4926: #0: ffff88806b3c3098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:244 #1: ffff88806b3c3130 (&tty->atomic_write_lock){+.+.}-{3:3}, at: tty_write_lock drivers/tty/tty_io.c:950 [inline] #1: ffff88806b3c3130 (&tty->atomic_write_lock){+.+.}-{3:3}, at: do_tty_write drivers/tty/tty_io.c:973 [inline] #1: ffff88806b3c3130 (&tty->atomic_write_lock){+.+.}-{3:3}, at: file_tty_write.constprop.0+0x296/0x8f0 drivers/tty/tty_io.c:1095 #2: ffff88806b3c32e8 (&o_tty->termios_rwsem/1){++++}-{3:3}, at: n_tty_write+0x1bf/0xfd0 drivers/tty/n_tty.c:2333 #3: ffffc90000cf4380 (&ldata->output_lock){+.+.}-{3:3}, at: process_output_block drivers/tty/n_tty.c:541 [inline] #3: ffffc90000cf4380 (&ldata->output_lock){+.+.}-{3:3}, at: n_tty_write+0x5f6/0xfd0 drivers/tty/n_tty.c:2350 #4: ffff88802624c958 (&port->lock){-.-.}-{2:2}, at: tty_insert_flip_string_and_push_buffer+0x2b/0x160 drivers/tty/tty_buffer.c:628 stack backtrace: CPU: 1 PID: 4926 Comm: syz-executor.0 Not tainted 6.0.0-rc7-syzkaller-00162-g5a77386984b5 #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014 Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2175 check_prev_add kernel/locking/lockdep.c:3095 [inline] check_prevs_add kernel/locking/lockdep.c:3214 [inline] validate_chain kernel/locking/lockdep.c:3829 [inline] __lock_acquire+0x2a43/0x56d0 kernel/locking/lockdep.c:5053 lock_acquire kernel/locking/lockdep.c:5666 [inline] lock_acquire+0x1ab/0x570 kernel/locking/lockdep.c:5631 seqcount_lockdep_reader_access include/linux/seqlock.h:102 [inline] read_seqbegin include/linux/seqlock.h:836 [inline] zonelist_iter_begin mm/page_alloc.c:4722 [inline] __alloc_pages_slowpath.constprop.0+0x1a5/0x2300 mm/page_alloc.c:5044 __alloc_pages+0x43d/0x510 mm/page_alloc.c:5562 __alloc_pages_node include/linux/gfp.h:243 [inline] kmem_getpages mm/slab.c:1363 [inline] cache_grow_begin+0x75/0x360 mm/slab.c:2569 cache_alloc_refill+0x27f/0x380 mm/slab.c:2942 ____cache_alloc mm/slab.c:3018 [inline] ____cache_alloc mm/slab.c:3001 [inline] __do_cache_alloc mm/slab.c:3246 [inline] slab_alloc mm/slab.c:3287 [inline] __do_kmalloc mm/slab.c:3684 [inline] __kmalloc+0x3a1/0x4a0 mm/slab.c:3695 kmalloc include/linux/slab.h:605 [inline] tty_buffer_alloc+0x27b/0x2f0 drivers/tty/tty_buffer.c:180 __tty_buffer_request_room+0x15f/0x2b0 drivers/tty/tty_buffer.c:278 tty_insert_flip_string_fixed_flag+0x8c/0x250 drivers/tty/tty_buffer.c:327 tty_insert_flip_string include/linux/tty_flip.h:41 [inline] tty_insert_flip_string_and_push_buffer+0x3e/0x160 drivers/tty/tty_buffer.c:629 pty_write+0xd6/0x100 drivers/tty/pty.c:118 process_output_block drivers/tty/n_tty.c:586 [inline] n_tty_write+0x4ca/0xfd0 drivers/tty/n_tty.c:2350 do_tty_write drivers/tty/tty_io.c:1024 [inline] file_tty_write.constprop.0+0x499/0x8f0 drivers/tty/tty_io.c:1095 call_write_iter include/linux/fs.h:2187 [inline] new_sync_write fs/read_write.c:491 [inline] vfs_write+0x9e9/0xdd0 fs/read_write.c:584 ksys_write+0x127/0x250 fs/read_write.c:637 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+0x63/0xcd RIP: 0033:0x7feffde8a5a9 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 RSP: 002b:00007feffcdfe168 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007feffdfabf80 RCX: 00007feffde8a5a9 RDX: 00000000fffffedf RSI: 0000000020000000 RDI: 0000000000000004 RBP: 00007feffdee5580 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fffc3837d3f R14: 00007feffcdfe300 R15: 0000000000022000 </TASK> --- This report is generated by a bot. 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