syzbot has found a reproducer for the following issue on: HEAD commit: 65aca32efdcb Merge tag 'mm-hotfixes-stable-2023-03-24-17-0.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=17b21b0ec80000 kernel config: https://syzkaller.appspot.com/x/.config?x=8ef27c4ff127cda5 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 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1591ba51c80000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12ac6789c80000 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 6.3.0-rc3-syzkaller-00317-g65aca32efdcb #0 Not tainted ------------------------------------------------------ syz-executor930/5168 is trying to acquire lock: ffffffff8c8e11e8 (zonelist_update_seq.seqcount){...-}-{0:0}, at: __alloc_pages+0x408/0x4a0 mm/page_alloc.c:5605 but task is already holding lock: ffff888014325958 (&port->lock){-...}-{2:2}, at: tty_insert_flip_string_and_push_buffer+0x2f/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+0x3d/0x60 kernel/locking/spinlock.c:162 tty_port_tty_get+0x21/0xf0 drivers/tty/tty_port.c:327 tty_port_default_wakeup+0x15/0x40 drivers/tty/tty_port.c:68 serial8250_tx_chars+0x53e/0xdf0 drivers/tty/serial/8250/8250_port.c:1865 serial8250_handle_irq.part.0+0x460/0x870 drivers/tty/serial/8250/8250_port.c:1955 serial8250_handle_irq drivers/tty/serial/8250/8250_port.c:1928 [inline] serial8250_default_handle_irq+0xb6/0x230 drivers/tty/serial/8250/8250_port.c:1975 serial8250_interrupt+0xfc/0x200 drivers/tty/serial/8250/8250_core.c:127 __handle_irq_event_percpu+0x22b/0x730 kernel/irq/handle.c:158 handle_irq_event_percpu kernel/irq/handle.c:193 [inline] handle_irq_event+0xab/0x1e0 kernel/irq/handle.c:210 handle_edge_irq+0x263/0xd00 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+0xa1/0x220 arch/x86/kernel/irq.c:250 common_interrupt+0xa8/0xd0 arch/x86/kernel/irq.c:240 asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:636 native_safe_halt arch/x86/include/asm/irqflags.h:48 [inline] arch_safe_halt arch/x86/include/asm/irqflags.h:86 [inline] default_idle+0xf/0x20 arch/x86/kernel/process.c:703 default_idle_call+0x67/0xa0 kernel/sched/idle.c:97 cpuidle_idle_call kernel/sched/idle.c:170 [inline] do_idle+0x31e/0x3e0 kernel/sched/idle.c:282 cpu_startup_entry+0x18/0x20 kernel/sched/idle.c:379 start_secondary+0x221/0x2b0 arch/x86/kernel/smpboot.c:264 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+0x3d/0x60 kernel/locking/spinlock.c:162 serial8250_console_write+0x4ba/0x1010 drivers/tty/serial/8250/8250_port.c:3401 console_emit_next_record kernel/printk/printk.c:2886 [inline] console_flush_all+0x49c/0xcc0 kernel/printk/printk.c:2942 console_unlock+0xb8/0x1f0 kernel/printk/printk.c:3016 vprintk_emit+0x1bd/0x600 kernel/printk/printk.c:2316 vprintk+0x84/0xa0 kernel/printk/printk_safe.c:50 _printk+0xbf/0xf0 kernel/printk/printk.c:2337 register_console+0x7ef/0x10e0 kernel/printk/printk.c:3467 univ8250_console_init+0x38/0x50 drivers/tty/serial/8250/8250_core.c:688 console_init+0xba/0x5c0 kernel/printk/printk.c:3610 start_kernel+0x273/0x4d0 init/main.c:1081 secondary_startup_64_no_verify+0xce/0xdb -> #1 (console_owner){....}-{0:0}: console_lock_spinning_enable kernel/printk/printk.c:1867 [inline] console_emit_next_record kernel/printk/printk.c:2880 [inline] console_flush_all+0x472/0xcc0 kernel/printk/printk.c:2942 console_unlock+0xb8/0x1f0 kernel/printk/printk.c:3016 vprintk_emit+0x1bd/0x600 kernel/printk/printk.c:2316 vprintk+0x84/0xa0 kernel/printk/printk_safe.c:50 _printk+0xbf/0xf0 kernel/printk/printk.c:2337 build_zonelists+0x357/0x560 mm/page_alloc.c:6543 __build_all_zonelists+0x122/0x180 mm/page_alloc.c:6656 build_all_zonelists_init+0x1c/0x190 mm/page_alloc.c:6681 build_all_zonelists+0x4a/0x150 mm/page_alloc.c:6714 start_kernel+0xb7/0x4d0 init/main.c:975 secondary_startup_64_no_verify+0xce/0xdb -> #0 (zonelist_update_seq.seqcount){...-}-{0:0}: check_prev_add kernel/locking/lockdep.c:3098 [inline] check_prevs_add kernel/locking/lockdep.c:3217 [inline] validate_chain kernel/locking/lockdep.c:3832 [inline] __lock_acquire+0x2ec7/0x5d40 kernel/locking/lockdep.c:5056 lock_acquire kernel/locking/lockdep.c:5669 [inline] lock_acquire+0x1af/0x520 kernel/locking/lockdep.c:5634 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:4765 [inline] __alloc_pages_slowpath.constprop.0+0x15a/0x2170 mm/page_alloc.c:5086 __alloc_pages+0x408/0x4a0 mm/page_alloc.c:5605 __alloc_pages_node include/linux/gfp.h:237 [inline] kmem_getpages mm/slab.c:1360 [inline] cache_grow_begin+0x9b/0x3b0 mm/slab.c:2570 cache_alloc_refill+0x27f/0x380 mm/slab.c:2943 ____cache_alloc mm/slab.c:3019 [inline] ____cache_alloc mm/slab.c:3002 [inline] __do_cache_alloc mm/slab.c:3202 [inline] slab_alloc_node mm/slab.c:3250 [inline] __kmem_cache_alloc_node+0x360/0x3f0 mm/slab.c:3541 __do_kmalloc_node mm/slab_common.c:966 [inline] __kmalloc+0x4e/0x190 mm/slab_common.c:980 kmalloc include/linux/slab.h:584 [inline] tty_buffer_alloc+0x275/0x2f0 drivers/tty/tty_buffer.c:180 __tty_buffer_request_room+0x15b/0x2d0 drivers/tty/tty_buffer.c:278 tty_insert_flip_string_fixed_flag+0x90/0x250 drivers/tty/tty_buffer.c:327 tty_insert_flip_string include/linux/tty_flip.h:41 [inline] tty_insert_flip_string_and_push_buffer+0x42/0x160 drivers/tty/tty_buffer.c:629 pty_write+0xda/0x100 drivers/tty/pty.c:118 ppp_async_push+0x5cb/0x1660 drivers/net/ppp/ppp_async.c:670 ppp_async_send+0xe2/0x110 drivers/net/ppp/ppp_async.c:638 __ppp_channel_push+0xe3/0x230 drivers/net/ppp/ppp_generic.c:2150 ppp_channel_push+0x1c2/0x250 drivers/net/ppp/ppp_generic.c:2177 ppp_write+0x22b/0x2d0 drivers/net/ppp/ppp_generic.c:523 do_loop_readv_writev fs/read_write.c:759 [inline] do_loop_readv_writev fs/read_write.c:743 [inline] do_iter_write+0x4ef/0x700 fs/read_write.c:863 vfs_writev+0x1aa/0x670 fs/read_write.c:934 do_pwritev fs/read_write.c:1031 [inline] __do_sys_pwritev fs/read_write.c:1078 [inline] __se_sys_pwritev fs/read_write.c:1073 [inline] __x64_sys_pwritev+0x22f/0x310 fs/read_write.c:1073 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x39/0xb0 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 *** 4 locks held by syz-executor930/5168: #0: ffff888000630a48 (&pch->upl){.+..}-{2:2}, at: ppp_channel_push+0x28/0x250 drivers/net/ppp/ppp_generic.c:2171 #1: ffff8880006309e0 (&pch->downl){+...}-{2:2}, at: spin_lock include/linux/spinlock.h:350 [inline] #1: ffff8880006309e0 (&pch->downl){+...}-{2:2}, at: __ppp_channel_push+0x2a/0x230 drivers/net/ppp/ppp_generic.c:2146 #2: ffff8880283b8030 (&ap->xmit_lock){+...}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:355 [inline] #2: ffff8880283b8030 (&ap->xmit_lock){+...}-{2:2}, at: ppp_async_push+0xb2/0x1660 drivers/net/ppp/ppp_async.c:663 #3: ffff888014325958 (&port->lock){-...}-{2:2}, at: tty_insert_flip_string_and_push_buffer+0x2f/0x160 drivers/tty/tty_buffer.c:628 stack backtrace: CPU: 0 PID: 5168 Comm: syz-executor930 Not tainted 6.3.0-rc3-syzkaller-00317-g65aca32efdcb #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+0xd9/0x150 lib/dump_stack.c:106 check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2178 check_prev_add kernel/locking/lockdep.c:3098 [inline] check_prevs_add kernel/locking/lockdep.c:3217 [inline] validate_chain kernel/locking/lockdep.c:3832 [inline] __lock_acquire+0x2ec7/0x5d40 kernel/locking/lockdep.c:5056 lock_acquire kernel/locking/lockdep.c:5669 [inline] lock_acquire+0x1af/0x520 kernel/locking/lockdep.c:5634 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:4765 [inline] __alloc_pages_slowpath.constprop.0+0x15a/0x2170 mm/page_alloc.c:5086 __alloc_pages+0x408/0x4a0 mm/page_alloc.c:5605 __alloc_pages_node include/linux/gfp.h:237 [inline] kmem_getpages mm/slab.c:1360 [inline] cache_grow_begin+0x9b/0x3b0 mm/slab.c:2570 cache_alloc_refill+0x27f/0x380 mm/slab.c:2943 ____cache_alloc mm/slab.c:3019 [inline] ____cache_alloc mm/slab.c:3002 [inline] __do_cache_alloc mm/slab.c:3202 [inline] slab_alloc_node mm/slab.c:3250 [inline] __kmem_cache_alloc_node+0x360/0x3f0 mm/slab.c:3541 __do_kmalloc_node mm/slab_common.c:966 [inline] __kmalloc+0x4e/0x190 mm/slab_common.c:980 kmalloc include/linux/slab.h:584 [inline] tty_buffer_alloc+0x275/0x2f0 drivers/tty/tty_buffer.c:180 __tty_buffer_request_room+0x15b/0x2d0 drivers/tty/tty_buffer.c:278 tty_insert_flip_string_fixed_flag+0x90/0x250 drivers/tty/tty_buffer.c:327 tty_insert_flip_string include/linux/tty_flip.h:41 [inline] tty_insert_flip_string_and_push_buffer+0x42/0x160 drivers/tty/tty_buffer.c:629 pty_write+0xda/0x100 drivers/tty/pty.c:118 ppp_async_push+0x5cb/0x1660 drivers/net/ppp/ppp_async.c:670 ppp_async_send+0xe2/0x110 drivers/net/ppp/ppp_async.c:638 __ppp_channel_push+0xe3/0x230 drivers/net/ppp/ppp_generic.c:2150 ppp_channel_push+0x1c2/0x250 drivers/net/ppp/ppp_generic.c:2177 ppp_write+0x22b/0x2d0 drivers/net/ppp/ppp_generic.c:523 do_loop_readv_writev fs/read_write.c:759 [inline] do_loop_readv_writev fs/read_write.c:743 [inline] do_iter_write+0x4ef/0x700 fs/read_write.c:863 vfs_writev+0x1aa/0x670 fs/read_write.c:934 do_pwritev fs/read_write.c:1031 [inline] __do_sys_pwritev fs/read_write.c:1078 [inline] __se_sys_pwritev fs/read_write.c:1073 [inline] __x64_sys_pwritev+0x22f/0x310 fs/read_write.c:1073 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7f76be0b97d9 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 41 15 00 00 90 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 c0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fffcac24418 EFLAGS: 00000246 ORIG_RAX: 0000000000000128 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007f76be0b97d9 RDX: 0000000000000003 RSI: 0000000020000380 RDI: 0000000000000004 RBP: 0000000000000000 R08: 0000000000000004 R09: 000000000000000d R10: 00000000000000f1 R11: 0000000000000246 R12: 00007fffcac24430 R13: 00000000000f4240 R14: 0000000000000000 R15: 0000000000000000 </TASK>
