======================================================== WARNING: possible irq lock inversion dependency detected 6.11.0-syzkaller-11993-g3efc57369a0c #0 Not tainted -------------------------------------------------------- kworker/u8:8/2958 just changed the state of lock: ffff88804cf74e10 (&ppp->rlock){+.-.}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:356 [inline] ffff88804cf74e10 (&ppp->rlock){+.-.}-{2:2}, at: ppp_do_recv+0x38/0x26b0 drivers/net/ppp/ppp_generic.c:2210 but this lock took another, SOFTIRQ-unsafe lock in the past: (&pch->downl){+.+.}-{2:2} and interrupts could create inverse lock ordering between them. other info that might help us debug this: Possible interrupt unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&pch->downl); local_irq_disable(); lock(&ppp->rlock); lock(&pch->downl); lock(&ppp->rlock); *** DEADLOCK *** 5 locks held by kworker/u8:8/2958: #0: ffff88801ac89148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3204 [inline] #0: ffff88801ac89148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x93b/0x1850 kernel/workqueue.c:3310 #1: ffffc90009cd7d00 ((work_completion)(&buf->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3205 [inline] #1: ffffc90009cd7d00 ((work_completion)(&buf->work)){+.+.}-{0:0}, at: process_scheduled_works+0x976/0x1850 kernel/workqueue.c:3310 #2: ffff8880541d80b8 (&buf->lock){+.+.}-{3:3}, at: flush_to_ldisc+0x38/0x860 drivers/tty/tty_buffer.c:467 #3: ffff8880496d30a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref+0x1c/0x80 drivers/tty/tty_ldisc.c:263 #4: ffff88803109a248 (&pch->upl){++.-}-{2:2}, at: ppp_input+0x3dc/0xa10 drivers/net/ppp/ppp_generic.c:2307 the shortest dependencies between 2nd lock and 1st lock: -> (&pch->downl){+.+.}-{2:2} { HARDIRQ-ON-W at: lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5822 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline] _raw_spin_lock_bh+0x35/0x50 kernel/locking/spinlock.c:178 spin_lock_bh include/linux/spinlock.h:356 [inline] ppp_unregister_channel+0x7c/0x300 drivers/net/ppp/ppp_generic.c:2992 pppox_unbind_sock+0x5c/0xb0 drivers/net/ppp/pppox.c:58 pppol2tp_release+0x99/0x230 net/l2tp/l2tp_ppp.c:436 __sock_release net/socket.c:658 [inline] sock_close+0xbc/0x240 net/socket.c:1426 __fput+0x23f/0x880 fs/file_table.c:431 task_work_run+0x24f/0x310 kernel/task_work.c:228 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] exit_to_user_mode_loop kernel/entry/common.c:114 [inline] exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline] __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline] syscall_exit_to_user_mode+0x168/0x370 kernel/entry/common.c:218 do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89 entry_SYSCALL_64_after_hwframe+0x77/0x7f SOFTIRQ-ON-W at: lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5822 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline] _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154 spin_lock include/linux/spinlock.h:351 [inline] ppp_channel_bridge_input drivers/net/ppp/ppp_generic.c:2272 [inline] ppp_input+0x18b/0xa10 drivers/net/ppp/ppp_generic.c:2304 pppoe_rcv_core+0x117/0x310 drivers/net/ppp/pppoe.c:379 sk_backlog_rcv include/net/sock.h:1113 [inline] __release_sock+0x243/0x350 net/core/sock.c:3072 release_sock+0x61/0x1f0 net/core/sock.c:3626 pppoe_sendmsg+0xd5/0x750 drivers/net/ppp/pppoe.c:903 sock_sendmsg_nosec net/socket.c:729 [inline] __sock_sendmsg+0x221/0x270 net/socket.c:744 ____sys_sendmsg+0x52a/0x7e0 net/socket.c:2602 ___sys_sendmsg net/socket.c:2656 [inline] __sys_sendmmsg+0x3ab/0x730 net/socket.c:2742 __do_sys_sendmmsg net/socket.c:2771 [inline] __se_sys_sendmmsg net/socket.c:2768 [inline] __x64_sys_sendmmsg+0xa0/0xb0 net/socket.c:2768 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f INITIAL USE at: lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5822 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline] _raw_spin_lock_bh+0x35/0x50 kernel/locking/spinlock.c:178 spin_lock_bh include/linux/spinlock.h:356 [inline] ppp_unregister_channel+0x7c/0x300 drivers/net/ppp/ppp_generic.c:2992 pppox_unbind_sock+0x5c/0xb0 drivers/net/ppp/pppox.c:58 pppol2tp_release+0x99/0x230 net/l2tp/l2tp_ppp.c:436 __sock_release net/socket.c:658 [inline] sock_close+0xbc/0x240 net/socket.c:1426 __fput+0x23f/0x880 fs/file_table.c:431 task_work_run+0x24f/0x310 kernel/task_work.c:228 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] exit_to_user_mode_loop kernel/entry/common.c:114 [inline] exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline] __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline] syscall_exit_to_user_mode+0x168/0x370 kernel/entry/common.c:218 do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89 entry_SYSCALL_64_after_hwframe+0x77/0x7f } ... key at: [] ppp_register_net_channel.__key.1+0x0/0x20 ... acquired at: lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5822 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline] _raw_spin_lock_bh+0x35/0x50 kernel/locking/spinlock.c:178 spin_lock_bh include/linux/spinlock.h:356 [inline] ppp_connect_channel+0x194/0x650 drivers/net/ppp/ppp_generic.c:3485 ppp_ioctl+0xdd4/0x1cd0 drivers/net/ppp/ppp_generic.c:761 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:907 [inline] __se_sys_ioctl+0xf9/0x170 fs/ioctl.c:893 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> (&ppp->rlock){+.-.}-{2:2} { HARDIRQ-ON-W at: lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5822 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline] _raw_spin_lock_bh+0x35/0x50 kernel/locking/spinlock.c:178 spin_lock_bh include/linux/spinlock.h:356 [inline] ppp_get_stats64+0x33/0x290 drivers/net/ppp/ppp_generic.c:1534 dev_get_stats+0xad/0xa00 net/core/dev.c:10937 rtnl_fill_stats+0x47/0x880 net/core/rtnetlink.c:1268 rtnl_fill_ifinfo+0x18da/0x2270 net/core/rtnetlink.c:1909 rtmsg_ifinfo_build_skb+0x18a/0x260 net/core/rtnetlink.c:4079 rtmsg_ifinfo_event net/core/rtnetlink.c:4112 [inline] rtmsg_ifinfo+0x91/0x1b0 net/core/rtnetlink.c:4121 register_netdevice+0x1774/0x1b00 net/core/dev.c:10534 ppp_unit_register drivers/net/ppp/ppp_generic.c:1219 [inline] ppp_dev_configure+0x883/0xb10 drivers/net/ppp/ppp_generic.c:1275 ppp_create_interface drivers/net/ppp/ppp_generic.c:3348 [inline] ppp_unattached_ioctl drivers/net/ppp/ppp_generic.c:1060 [inline] ppp_ioctl+0x797/0x1cd0 drivers/net/ppp/ppp_generic.c:733 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:907 [inline] __se_sys_ioctl+0xf9/0x170 fs/ioctl.c:893 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f IN-SOFTIRQ-W at: lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5822 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline] _raw_spin_lock_bh+0x35/0x50 kernel/locking/spinlock.c:178 spin_lock_bh include/linux/spinlock.h:356 [inline] ppp_do_recv+0x38/0x26b0 drivers/net/ppp/ppp_generic.c:2210 ppp_input+0x5de/0xa10 drivers/net/ppp/ppp_generic.c:2327 ppp_async_process+0x7f/0x150 drivers/net/ppp/ppp_async.c:495 tasklet_action_common+0x321/0x4d0 kernel/softirq.c:784 handle_softirqs+0x2c5/0x980 kernel/softirq.c:554 __do_softirq kernel/softirq.c:588 [inline] invoke_softirq kernel/softirq.c:428 [inline] __irq_exit_rcu+0xf4/0x1c0 kernel/softirq.c:637 irq_exit_rcu+0x9/0x30 kernel/softirq.c:649 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1037 [inline] sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1037 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 preempt_schedule_irq+0xf6/0x1c0 kernel/sched/core.c:6997 irqentry_exit+0x5e/0x90 kernel/entry/common.c:354 asm_sysvec_reschedule_ipi+0x1a/0x20 arch/x86/include/asm/idtentry.h:707 __tasklet_schedule_common+0x1fd/0x270 kernel/softirq.c:733 tasklet_schedule include/linux/interrupt.h:719 [inline] ppp_asynctty_receive+0x1ea6/0x2000 drivers/net/ppp/ppp_async.c:345 tty_ldisc_receive_buf+0x11f/0x170 drivers/tty/tty_buffer.c:391 tty_port_default_receive_buf+0x6d/0xa0 drivers/tty/tty_port.c:37 receive_buf drivers/tty/tty_buffer.c:445 [inline] flush_to_ldisc+0x328/0x860 drivers/tty/tty_buffer.c:495 process_one_work kernel/workqueue.c:3229 [inline] process_scheduled_works+0xa63/0x1850 kernel/workqueue.c:3310 worker_thread+0x870/0xd30 kernel/workqueue.c:3391 kthread+0x2f0/0x390 kernel/kthread.c:389 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 INITIAL USE at: lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5822 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline] _raw_spin_lock_bh+0x35/0x50 kernel/locking/spinlock.c:178 spin_lock_bh include/linux/spinlock.h:356 [inline] ppp_get_stats64+0x33/0x290 drivers/net/ppp/ppp_generic.c:1534 dev_get_stats+0xad/0xa00 net/core/dev.c:10937 rtnl_fill_stats+0x47/0x880 net/core/rtnetlink.c:1268 rtnl_fill_ifinfo+0x18da/0x2270 net/core/rtnetlink.c:1909 rtmsg_ifinfo_build_skb+0x18a/0x260 net/core/rtnetlink.c:4079 rtmsg_ifinfo_event net/core/rtnetlink.c:4112 [inline] rtmsg_ifinfo+0x91/0x1b0 net/core/rtnetlink.c:4121 register_netdevice+0x1774/0x1b00 net/core/dev.c:10534 ppp_unit_register drivers/net/ppp/ppp_generic.c:1219 [inline] ppp_dev_configure+0x883/0xb10 drivers/net/ppp/ppp_generic.c:1275 ppp_create_interface drivers/net/ppp/ppp_generic.c:3348 [inline] ppp_unattached_ioctl drivers/net/ppp/ppp_generic.c:1060 [inline] ppp_ioctl+0x797/0x1cd0 drivers/net/ppp/ppp_generic.c:733 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:907 [inline] __se_sys_ioctl+0xf9/0x170 fs/ioctl.c:893 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f } ... key at: [] ppp_dev_configure.__key+0x0/0x20 ... acquired at: mark_lock+0x223/0x360 kernel/locking/lockdep.c:4722 __lock_acquire+0xbf9/0x2050 kernel/locking/lockdep.c:5153 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5822 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline] _raw_spin_lock_bh+0x35/0x50 kernel/locking/spinlock.c:178 spin_lock_bh include/linux/spinlock.h:356 [inline] ppp_do_recv+0x38/0x26b0 drivers/net/ppp/ppp_generic.c:2210 ppp_input+0x5de/0xa10 drivers/net/ppp/ppp_generic.c:2327 ppp_async_process+0x7f/0x150 drivers/net/ppp/ppp_async.c:495 tasklet_action_common+0x321/0x4d0 kernel/softirq.c:784 handle_softirqs+0x2c5/0x980 kernel/softirq.c:554 __do_softirq kernel/softirq.c:588 [inline] invoke_softirq kernel/softirq.c:428 [inline] __irq_exit_rcu+0xf4/0x1c0 kernel/softirq.c:637 irq_exit_rcu+0x9/0x30 kernel/softirq.c:649 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1037 [inline] sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1037 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 preempt_schedule_irq+0xf6/0x1c0 kernel/sched/core.c:6997 irqentry_exit+0x5e/0x90 kernel/entry/common.c:354 asm_sysvec_reschedule_ipi+0x1a/0x20 arch/x86/include/asm/idtentry.h:707 __tasklet_schedule_common+0x1fd/0x270 kernel/softirq.c:733 tasklet_schedule include/linux/interrupt.h:719 [inline] ppp_asynctty_receive+0x1ea6/0x2000 drivers/net/ppp/ppp_async.c:345 tty_ldisc_receive_buf+0x11f/0x170 drivers/tty/tty_buffer.c:391 tty_port_default_receive_buf+0x6d/0xa0 drivers/tty/tty_port.c:37 receive_buf drivers/tty/tty_buffer.c:445 [inline] flush_to_ldisc+0x328/0x860 drivers/tty/tty_buffer.c:495 process_one_work kernel/workqueue.c:3229 [inline] process_scheduled_works+0xa63/0x1850 kernel/workqueue.c:3310 worker_thread+0x870/0xd30 kernel/workqueue.c:3391 kthread+0x2f0/0x390 kernel/kthread.c:389 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 stack backtrace: CPU: 0 UID: 0 PID: 2958 Comm: kworker/u8:8 Not tainted 6.11.0-syzkaller-11993-g3efc57369a0c #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 Workqueue: events_unbound flush_to_ldisc Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120 print_irq_inversion_bug+0x33d/0x390 kernel/locking/lockdep.c:4118 mark_lock_irq+0x80c/0xc20 kernel/locking/lockdep.c:4287 mark_lock+0x223/0x360 kernel/locking/lockdep.c:4722 __lock_acquire+0xbf9/0x2050 kernel/locking/lockdep.c:5153 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5822 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline] _raw_spin_lock_bh+0x35/0x50 kernel/locking/spinlock.c:178 spin_lock_bh include/linux/spinlock.h:356 [inline] ppp_do_recv+0x38/0x26b0 drivers/net/ppp/ppp_generic.c:2210 ppp_input+0x5de/0xa10 drivers/net/ppp/ppp_generic.c:2327 ppp_async_process+0x7f/0x150 drivers/net/ppp/ppp_async.c:495 tasklet_action_common+0x321/0x4d0 kernel/softirq.c:784 handle_softirqs+0x2c5/0x980 kernel/softirq.c:554 __do_softirq kernel/softirq.c:588 [inline] invoke_softirq kernel/softirq.c:428 [inline] __irq_exit_rcu+0xf4/0x1c0 kernel/softirq.c:637 irq_exit_rcu+0x9/0x30 kernel/softirq.c:649 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1037 [inline] sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1037 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:preempt_schedule_irq+0xf6/0x1c0 kernel/sched/core.c:6997 Code: 89 f5 49 c1 ed 03 eb 0d 48 f7 03 08 00 00 00 0f 84 8b 00 00 00 bf 01 00 00 00 e8 85 d9 95 f5 e8 70 51 cf f5 fb bf 01 00 00 00 85 ac ff ff 43 80 7c 3d 00 00 74 08 4c 89 f7 e8 35 41 31 f6 48 RSP: 0018:ffffc90009cd7740 EFLAGS: 00000286 RAX: e6de269ca7146a00 RBX: 1ffff9200139aef0 RCX: ffffffff8170b7ea RDX: dffffc0000000000 RSI: ffffffff8c0acac0 RDI: 0000000000000001 RBP: ffffc90009cd7800 R08: ffffffff9427585f R09: 1ffffffff284eb0b R10: dffffc0000000000 R11: fffffbfff284eb0c R12: 1ffff9200139aee8 R13: 1ffff9200139aeec R14: ffffc90009cd7760 R15: dffffc0000000000 irqentry_exit+0x5e/0x90 kernel/entry/common.c:354 asm_sysvec_reschedule_ipi+0x1a/0x20 arch/x86/include/asm/idtentry.h:707 RIP: 0010:__tasklet_schedule_common+0x1fd/0x270 kernel/softirq.c:733 Code: 40 42 80 3c 33 00 74 08 4c 89 ff e8 0d fe a6 00 f6 44 24 41 02 75 4f 41 f7 c5 00 02 00 00 74 01 fb 48 c7 44 24 20 0e 36 e0 45 <4b> c7 04 26 00 00 00 00 66 43 c7 44 26 09 00 00 43 c6 44 26 0b 00 RSP: 0018:ffffc90009cd78c0 EFLAGS: 00000206 RAX: e6de269ca7146a00 RBX: 1ffff9200139af20 RCX: ffffffff8170b7ea RDX: dffffc0000000000 RSI: ffffffff8c0acac0 RDI: ffffffff8c60f5a0 RBP: ffffc90009cd7998 R08: ffffffff9427585f R09: 1ffffffff284eb0b R10: dffffc0000000000 R11: fffffbfff284eb0c R12: 1ffff9200139af1c R13: 0000000000000246 R14: dffffc0000000000 R15: ffffc90009cd7900 tasklet_schedule include/linux/interrupt.h:719 [inline] ppp_asynctty_receive+0x1ea6/0x2000 drivers/net/ppp/ppp_async.c:345 tty_ldisc_receive_buf+0x11f/0x170 drivers/tty/tty_buffer.c:391 tty_port_default_receive_buf+0x6d/0xa0 drivers/tty/tty_port.c:37 receive_buf drivers/tty/tty_buffer.c:445 [inline] flush_to_ldisc+0x328/0x860 drivers/tty/tty_buffer.c:495 process_one_work kernel/workqueue.c:3229 [inline] process_scheduled_works+0xa63/0x1850 kernel/workqueue.c:3310 worker_thread+0x870/0xd30 kernel/workqueue.c:3391 kthread+0x2f0/0x390 kernel/kthread.c:389 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 vkms_vblank_simulate: vblank timer overrun ---------------- Code disassembly (best guess): 0: 89 f5 mov %esi,%ebp 2: 49 c1 ed 03 shr $0x3,%r13 6: eb 0d jmp 0x15 8: 48 f7 03 08 00 00 00 testq $0x8,(%rbx) f: 0f 84 8b 00 00 00 je 0xa0 15: bf 01 00 00 00 mov $0x1,%edi 1a: e8 85 d9 95 f5 call 0xf595d9a4 1f: e8 70 51 cf f5 call 0xf5cf5194 24: fb sti 25: bf 01 00 00 00 mov $0x1,%edi * 2a: e8 85 ac ff ff call 0xffffacb4 <-- trapping instruction 2f: 43 80 7c 3d 00 00 cmpb $0x0,0x0(%r13,%r15,1) 35: 74 08 je 0x3f 37: 4c 89 f7 mov %r14,%rdi 3a: e8 35 41 31 f6 call 0xf6314174 3f: 48 rex.W