Freezing user space processes ------------[ cut here ]------------ ====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.3.7/5815 is trying to acquire lock: ffffffff8eaf4160 (console_owner){....}-{0:0}, at: console_trylock_spinning kernel/printk/printk.c:2026 [inline] ffffffff8eaf4160 (console_owner){....}-{0:0}, at: vprintk_emit+0x4c0/0x6b0 kernel/printk/printk.c:2478 but task is already holding lock: ffff888033778a90 (&p->pi_lock){-.-.}-{2:2}, at: task_call_func+0x8b/0x380 kernel/sched/core.c:4476 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (&p->pi_lock){-.-.}-{2:2}: lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:132 [inline] _raw_spin_lock_irqsave+0x3a/0x60 kernel/locking/spinlock.c:166 class_raw_spinlock_irqsave_constructor include/linux/spinlock.h:571 [inline] try_to_wake_up+0xbd/0x1c90 kernel/sched/core.c:4292 __wake_up_common+0x135/0x1f0 kernel/sched/wait.c:108 __wake_up_common_lock kernel/sched/wait.c:125 [inline] __wake_up+0x31/0x60 kernel/sched/wait.c:146 tty_port_default_wakeup+0x47/0x60 drivers/tty/tty_port.c:67 serial8250_tx_chars+0x68f/0x860 drivers/tty/serial/8250/8250_port.c:1723 serial8250_handle_irq_locked+0x770/0x9a0 drivers/tty/serial/8250/8250_port.c:1837 serial8250_handle_irq.part.0+0xb4/0x530 drivers/tty/serial/8250/8250_port.c:1853 serial8250_handle_irq drivers/tty/serial/8250/8250_port.c:1849 [inline] serial8250_default_handle_irq+0xc2/0x280 drivers/tty/serial/8250/8250_port.c:1867 serial8250_interrupt+0xf8/0x1b0 drivers/tty/serial/8250/8250_core.c:86 __handle_irq_event_percpu+0x232/0x880 kernel/irq/handle.c:209 handle_irq_event_percpu kernel/irq/handle.c:246 [inline] handle_irq_event+0xab/0x1e0 kernel/irq/handle.c:263 handle_edge_irq+0x34c/0x950 kernel/irq/chip.c:859 generic_handle_irq_desc include/linux/irqdesc.h:188 [inline] handle_irq arch/x86/kernel/irq.c:209 [inline] call_irq_handler arch/x86/kernel/irq.c:265 [inline] __common_interrupt+0xd8/0x2f0 arch/x86/kernel/irq.c:280 common_interrupt+0x60/0xe0 arch/x86/kernel/irq.c:273 asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:665 stack_access_ok+0xdc/0x1d0 arch/x86/kernel/unwind_orc.c:414 deref_stack_reg arch/x86/kernel/unwind_orc.c:419 [inline] unwind_next_frame+0x1551/0x2090 arch/x86/kernel/unwind_orc.c:677 arch_stack_walk+0x94/0xf0 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122 kasan_save_stack+0x30/0x50 mm/kasan/common.c:57 kasan_save_track+0x14/0x30 mm/kasan/common.c:78 kasan_save_free_info+0x3b/0x70 mm/kasan/generic.c:584 poison_slab_object mm/kasan/common.c:253 [inline] __kasan_slab_free+0x5f/0x80 mm/kasan/common.c:285 kasan_slab_free include/linux/kasan.h:235 [inline] slab_free_hook mm/slub.c:2677 [inline] slab_free_after_rcu_debug+0xdf/0x170 mm/slub.c:6439 rcu_do_batch kernel/rcu/tree.c:2645 [inline] rcu_core+0x5a2/0x10d0 kernel/rcu/tree.c:2897 handle_softirqs+0x1ea/0x9b0 kernel/softirq.c:622 do_softirq kernel/softirq.c:523 [inline] do_softirq+0xac/0xe0 kernel/softirq.c:510 __local_bh_enable_ip+0xf8/0x120 kernel/softirq.c:450 local_bh_enable include/linux/bottom_half.h:33 [inline] __alloc_skb+0x5db/0x710 net/core/skbuff.c:699 alloc_skb include/linux/skbuff.h:1384 [inline] alloc_skb_with_frags+0xdd/0x760 net/core/skbuff.c:6775 sock_alloc_send_pskb+0x801/0x980 net/core/sock.c:3013 unix_dgram_sendmsg+0x3c7/0x1810 net/unix/af_unix.c:2137 sock_sendmsg_nosec net/socket.c:775 [inline] __sock_sendmsg net/socket.c:790 [inline] __sys_sendto+0x48b/0x4e0 net/socket.c:2252 __do_sys_sendto net/socket.c:2259 [inline] __se_sys_sendto net/socket.c:2255 [inline] __x64_sys_sendto+0xe0/0x1c0 net/socket.c:2255 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #2 (&tty->write_wait){-.-.}-{3:3}: lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:132 [inline] _raw_spin_lock_irqsave+0x3a/0x60 kernel/locking/spinlock.c:166 __wake_up_common_lock kernel/sched/wait.c:124 [inline] __wake_up+0x1c/0x60 kernel/sched/wait.c:146 tty_port_default_wakeup+0x47/0x60 drivers/tty/tty_port.c:67 serial8250_tx_chars+0x68f/0x860 drivers/tty/serial/8250/8250_port.c:1723 serial8250_handle_irq_locked+0x770/0x9a0 drivers/tty/serial/8250/8250_port.c:1837 serial8250_handle_irq.part.0+0xb4/0x530 drivers/tty/serial/8250/8250_port.c:1853 serial8250_handle_irq drivers/tty/serial/8250/8250_port.c:1849 [inline] serial8250_default_handle_irq+0xc2/0x280 drivers/tty/serial/8250/8250_port.c:1867 serial8250_interrupt+0xf8/0x1b0 drivers/tty/serial/8250/8250_core.c:86 __handle_irq_event_percpu+0x232/0x880 kernel/irq/handle.c:209 handle_irq_event_percpu kernel/irq/handle.c:246 [inline] handle_irq_event+0xab/0x1e0 kernel/irq/handle.c:263 handle_edge_irq+0x34c/0x950 kernel/irq/chip.c:859 generic_handle_irq_desc include/linux/irqdesc.h:188 [inline] handle_irq arch/x86/kernel/irq.c:209 [inline] call_irq_handler arch/x86/kernel/irq.c:265 [inline] __common_interrupt+0xd8/0x2f0 arch/x86/kernel/irq.c:280 common_interrupt+0xb9/0xe0 arch/x86/kernel/irq.c:273 asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:665 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:178 [inline] _raw_spin_unlock_irqrestore+0x31/0x80 kernel/locking/spinlock.c:198 spin_unlock_irqrestore include/linux/spinlock.h:408 [inline] uart_port_unlock_irqrestore include/linux/serial_core.h:790 [inline] uart_port_unlock_deref drivers/tty/serial/serial_core.c:91 [inline] uart_port_unlock_deref drivers/tty/serial/serial_core.c:88 [inline] uart_write+0x29d/0xb20 drivers/tty/serial/serial_core.c:630 process_output_block drivers/tty/n_tty.c:557 [inline] n_tty_write+0x431/0x1160 drivers/tty/n_tty.c:2366 iterate_tty_write drivers/tty/tty_io.c:1006 [inline] file_tty_write.isra.0+0x4d2/0x890 drivers/tty/tty_io.c:1081 tty_write drivers/tty/tty_io.c:1102 [inline] redirected_tty_write drivers/tty/tty_io.c:1125 [inline] redirected_tty_write+0xd4/0x120 drivers/tty/tty_io.c:1105 new_sync_write fs/read_write.c:595 [inline] vfs_write+0x6ac/0x1050 fs/read_write.c:687 ksys_write+0x12a/0x250 fs/read_write.c:739 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #1 (&port_lock_key){-.-.}-{3:3}: lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:132 [inline] _raw_spin_lock_irqsave+0x3a/0x60 kernel/locking/spinlock.c:166 uart_port_lock_irqsave include/linux/serial_core.h:719 [inline] serial8250_console_write+0x177/0x1a50 drivers/tty/serial/8250/8250_port.c:3344 console_emit_next_record kernel/printk/printk.c:3183 [inline] console_flush_one_record+0x790/0xe50 kernel/printk/printk.c:3269 console_flush_all kernel/printk/printk.c:3343 [inline] __console_flush_and_unlock kernel/printk/printk.c:3373 [inline] console_unlock+0x103/0x260 kernel/printk/printk.c:3413 vprintk_emit+0x407/0x6b0 kernel/printk/printk.c:2479 _printk+0xcf/0x110 kernel/printk/printk.c:2504 register_console.cold+0xc0/0x248 kernel/printk/printk.c:4208 univ8250_console_init+0x6f/0x80 drivers/tty/serial/8250/8250_core.c:515 console_init+0x3d5/0x5b0 kernel/printk/printk.c:4407 start_kernel+0x314/0x490 init/main.c:1112 x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:310 x86_64_start_kernel+0x12b/0x130 arch/x86/kernel/head64.c:291 common_startup_64+0x13e/0x158 -> #0 (console_owner){....}-{0:0}: check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3165 check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x136c/0x1a40 kernel/locking/lockdep.c:5237 lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825 console_trylock_spinning kernel/printk/printk.c:2026 [inline] vprintk_emit+0x4d1/0x6b0 kernel/printk/printk.c:2478 _printk+0xcf/0x110 kernel/printk/printk.c:2504 __report_bug.cold+0x34/0x141 lib/bug.c:248 report_bug+0xb2/0x220 lib/bug.c:286 handle_bug+0x16a/0x2a0 arch/x86/kernel/traps.c:436 exc_invalid_op+0x17/0x50 arch/x86/kernel/traps.c:490 asm_exc_invalid_op+0x1a/0x20 arch/x86/include/asm/idtentry.h:593 __set_task_frozen+0x211/0x2e0 kernel/freezer.c:139 task_call_func+0x169/0x380 kernel/sched/core.c:4495 __freeze_task kernel/freezer.c:150 [inline] freeze_task+0x151/0x270 kernel/freezer.c:169 try_to_freeze_tasks+0x243/0x680 kernel/power/process.c:54 freeze_processes+0xf2/0x1f0 kernel/power/process.c:137 suspend_freeze_processes kernel/power/power.h:281 [inline] suspend_prepare kernel/power/suspend.c:387 [inline] enter_state kernel/power/suspend.c:609 [inline] pm_suspend kernel/power/suspend.c:644 [inline] pm_suspend+0x32c/0x7b0 kernel/power/suspend.c:636 state_store+0x101/0x240 kernel/power/main.c:819 kobj_attr_store+0x58/0x80 lib/kobject.c:840 sysfs_kf_write+0xf2/0x150 fs/sysfs/file.c:145 kernfs_fop_write_iter+0x3e0/0x5f0 fs/kernfs/file.c:345 new_sync_write fs/read_write.c:595 [inline] vfs_write+0x6ac/0x1050 fs/read_write.c:687 ksys_write+0x12a/0x250 fs/read_write.c:739 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f other info that might help us debug this: Chain exists of: console_owner --> &tty->write_wait --> &p->pi_lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&p->pi_lock); lock(&tty->write_wait); lock(&p->pi_lock); lock(console_owner); *** DEADLOCK *** 8 locks held by syz.3.7/5815: #0: ffff8880331950b0 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x2aa/0x380 fs/file.c:1259 #1: ffff88803606c450 (sb_writers#8){.+.+}-{0:0}, at: ksys_write+0x12a/0x250 fs/read_write.c:739 #2: ffff8880320df880 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x2c2/0x5f0 fs/kernfs/file.c:336 #3: ffff88802068e968 (kn->active#65){.+.+}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:73 [inline] #3: ffff88802068e968 (kn->active#65){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x332/0x5f0 fs/kernfs/file.c:337 #4: ffffffff8ea9fc80 (system_transition_mutex){+.+.}-{4:4}, at: enter_state kernel/power/suspend.c:591 [inline] #4: ffffffff8ea9fc80 (system_transition_mutex){+.+.}-{4:4}, at: pm_suspend kernel/power/suspend.c:644 [inline] #4: ffffffff8ea9fc80 (system_transition_mutex){+.+.}-{4:4}, at: pm_suspend+0x586/0x7b0 kernel/power/suspend.c:636 #5: ffffffff8e80a098 (tasklist_lock){.+.+}-{3:3}, at: try_to_freeze_tasks+0x148/0x680 kernel/power/process.c:52 #6: ffffffff8ec181f8 (freezer_lock){....}-{3:3}, at: freeze_task+0x71/0x270 kernel/freezer.c:168 #7: ffff888033778a90 (&p->pi_lock){-.-.}-{2:2}, at: task_call_func+0x8b/0x380 kernel/sched/core.c:4476 stack backtrace: CPU: 0 UID: 0 PID: 5815 Comm: syz.3.7 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120 print_circular_bug.cold+0x178/0x1c7 kernel/locking/lockdep.c:2043 check_noncircular+0x146/0x160 kernel/locking/lockdep.c:2175 check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3165 check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x136c/0x1a40 kernel/locking/lockdep.c:5237 lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825 console_trylock_spinning kernel/printk/printk.c:2026 [inline] vprintk_emit+0x4d1/0x6b0 kernel/printk/printk.c:2478 _printk+0xcf/0x110 kernel/printk/printk.c:2504 __report_bug.cold+0x34/0x141 lib/bug.c:248 report_bug+0xb2/0x220 lib/bug.c:286 handle_bug+0x16a/0x2a0 arch/x86/kernel/traps.c:436 exc_invalid_op+0x17/0x50 arch/x86/kernel/traps.c:490 asm_exc_invalid_op+0x1a/0x20 arch/x86/include/asm/idtentry.h:593 RIP: 0010:__set_task_frozen+0x211/0x2e0 kernel/freezer.c:139 Code: 0f b6 04 02 84 c0 74 09 3c 03 7f 05 e8 d8 92 86 00 8b ab 98 0b 00 00 31 ff 89 ee e8 49 03 16 00 85 ed 74 09 e8 d0 08 16 00 90 <0f> 0b 90 e8 c7 08 16 00 4c 89 e2 48 b8 00 00 00 00 00 fc ff df 48 RSP: 0018:ffffc900050cf990 EFLAGS: 00010046 RAX: 0000000000080000 RBX: ffff888033778000 RCX: ffffc90006a0b000 RDX: 0000000000080000 RSI: ffffffff81f45c10 RDI: ffff88801ff04a80 RBP: 0000000000000003 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000003 R11: 0000000000000000 R12: ffff888033778018 R13: 0000000000000002 R14: dffffc0000000000 R15: ffff888033778a78 task_call_func+0x169/0x380 kernel/sched/core.c:4495 __freeze_task kernel/freezer.c:150 [inline] freeze_task+0x151/0x270 kernel/freezer.c:169 try_to_freeze_tasks+0x243/0x680 kernel/power/process.c:54 freeze_processes+0xf2/0x1f0 kernel/power/process.c:137 suspend_freeze_processes kernel/power/power.h:281 [inline] suspend_prepare kernel/power/suspend.c:387 [inline] enter_state kernel/power/suspend.c:609 [inline] pm_suspend kernel/power/suspend.c:644 [inline] pm_suspend+0x32c/0x7b0 kernel/power/suspend.c:636 state_store+0x101/0x240 kernel/power/main.c:819 kobj_attr_store+0x58/0x80 lib/kobject.c:840 sysfs_kf_write+0xf2/0x150 fs/sysfs/file.c:145 kernfs_fop_write_iter+0x3e0/0x5f0 fs/kernfs/file.c:345 new_sync_write fs/read_write.c:595 [inline] vfs_write+0x6ac/0x1050 fs/read_write.c:687 ksys_write+0x12a/0x250 fs/read_write.c:739 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fe82a59e019 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 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 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fe82b521028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007fe82a825fa0 RCX: 00007fe82a59e019 RDX: 0000000000000003 RSI: 0000200000000400 RDI: 0000000000000004 RBP: 00007fe82a63500c R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fe82a826038 R14: 00007fe82a825fa0 R15: 00007ffe01761138 debug_locks && p->lockdep_depth WARNING: kernel/freezer.c:139 at __set_task_frozen+0x211/0x2e0 kernel/freezer.c:139, CPU#0: syz.3.7/5815 Modules linked in: CPU: 0 UID: 0 PID: 5815 Comm: syz.3.7 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026 RIP: 0010:__set_task_frozen+0x211/0x2e0 kernel/freezer.c:139 Code: 0f b6 04 02 84 c0 74 09 3c 03 7f 05 e8 d8 92 86 00 8b ab 98 0b 00 00 31 ff 89 ee e8 49 03 16 00 85 ed 74 09 e8 d0 08 16 00 90 <0f> 0b 90 e8 c7 08 16 00 4c 89 e2 48 b8 00 00 00 00 00 fc ff df 48 RSP: 0018:ffffc900050cf990 EFLAGS: 00010046 RAX: 0000000000080000 RBX: ffff888033778000 RCX: ffffc90006a0b000 RDX: 0000000000080000 RSI: ffffffff81f45c10 RDI: ffff88801ff04a80 RBP: 0000000000000003 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000003 R11: 0000000000000000 R12: ffff888033778018 R13: 0000000000000002 R14: dffffc0000000000 R15: ffff888033778a78 FS: 00007fe82b5216c0(0000) GS:ffff888123dd8000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f92f2224d58 CR3: 000000007766b000 CR4: 00000000003526f0 Call Trace: task_call_func+0x169/0x380 kernel/sched/core.c:4495 __freeze_task kernel/freezer.c:150 [inline] freeze_task+0x151/0x270 kernel/freezer.c:169 try_to_freeze_tasks+0x243/0x680 kernel/power/process.c:54 freeze_processes+0xf2/0x1f0 kernel/power/process.c:137 suspend_freeze_processes kernel/power/power.h:281 [inline] suspend_prepare kernel/power/suspend.c:387 [inline] enter_state kernel/power/suspend.c:609 [inline] pm_suspend kernel/power/suspend.c:644 [inline] pm_suspend+0x32c/0x7b0 kernel/power/suspend.c:636 state_store+0x101/0x240 kernel/power/main.c:819 kobj_attr_store+0x58/0x80 lib/kobject.c:840 sysfs_kf_write+0xf2/0x150 fs/sysfs/file.c:145 kernfs_fop_write_iter+0x3e0/0x5f0 fs/kernfs/file.c:345 new_sync_write fs/read_write.c:595 [inline] vfs_write+0x6ac/0x1050 fs/read_write.c:687 ksys_write+0x12a/0x250 fs/read_write.c:739 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fe82a59e019 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 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 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fe82b521028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007fe82a825fa0 RCX: 00007fe82a59e019 RDX: 0000000000000003 RSI: 0000200000000400 RDI: 0000000000000004 RBP: 00007fe82a63500c R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fe82a826038 R14: 00007fe82a825fa0 R15: 00007ffe01761138