syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	1-...!: (1 ticks this GP) idle=3f24/1/0x4000000000000000 softirq=224419/224419 fqs=0
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P22708/1:b..l P14225/1:b..l
rcu: 	(detected by 0, t=10502 jiffies, g=213257, q=1369 ncpus=2)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 14246 Comm: syz.7.5495 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:hlock_class kernel/locking/lockdep.c:234 [inline]
RIP: 0010:mark_lock+0x3c/0x190 kernel/locking/lockdep.c:4731
Code: 00 03 00 83 f9 01 bb 09 00 00 00 83 db 00 83 fa 08 0f 45 da bd 01 00 00 00 89 d9 d3 e5 25 ff 1f 00 00 48 0f a3 05 64 06 d9 11 <73> 10 48 69 c0 c8 00 00 00 48 8d 88 30 e3 17 93 eb 48 83 3d eb 95
RSP: 0018:ffffc90000a08a78 EFLAGS: 00000047
RAX: 0000000000000000 RBX: 0000000000000008 RCX: 0000000000000008
RDX: 0000000000000008 RSI: ffff888060ece618 RDI: ffff888060ecdac0
RBP: 0000000000000100 R08: 0000000000000000 R09: ffffffff849486db
R10: ffffc90000a08ca0 R11: fffff52000141196 R12: 0000000000000002
R13: 0000000000000002 R14: ffff888060ece618 R15: 0000000000000000
FS:  00007f2a0b8e36c0(0000) GS:ffff88812622d000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00002000001ca030 CR3: 0000000028f5c000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 3a810b1eb6134bdc DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 mark_usage kernel/locking/lockdep.c:4674 [inline]
 __lock_acquire+0x6a8/0xd20 kernel/locking/lockdep.c:5191
 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
 _raw_spin_lock_irqsave+0xa7/0xf0 kernel/locking/spinlock.c:162
 debug_object_activate+0xbb/0x420 lib/debugobjects.c:818
 debug_hrtimer_activate kernel/time/hrtimer.c:438 [inline]
 debug_activate kernel/time/hrtimer.c:477 [inline]
 enqueue_hrtimer+0x30/0x3a0 kernel/time/hrtimer.c:1081
 __run_hrtimer kernel/time/hrtimer.c:1794 [inline]
 __hrtimer_run_queues+0x656/0xc60 kernel/time/hrtimer.c:1841
 hrtimer_interrupt+0x45b/0xaa0 kernel/time/hrtimer.c:1903
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1041 [inline]
 __sysvec_apic_timer_interrupt+0x10b/0x410 arch/x86/kernel/apic/apic.c:1058
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1052 [inline]
 sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1052
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:sock_recvmsg_nosec+0x136/0x1c0 net/socket.c:-1
Code: 57 28 4c 89 f7 4c 89 fe 8b 4c 24 04 e8 43 a9 ae 00 e9 73 ff ff ff e8 19 3b a2 f8 80 7c 1d 00 00 74 08 4c 89 e7 e8 0a 0d 08 f9 <41> bd 90 00 00 00 4d 03 2c 24 4c 89 e8 48 c1 e8 03 80 3c 18 00 74
RSP: 0018:ffffc9000f327880 EFLAGS: 00000246
RAX: ffffffff891e4237 RBX: dffffc0000000000 RCX: 0000000000080000
RDX: ffffc9001b8de000 RSI: 000000000007ffff RDI: 0000000000080000
RBP: 1ffff1100ee68f1c R08: ffffc9000f3279bf R09: 0000000000000000
R10: ffffc9000f327940 R11: fffff52001e64f38 R12: ffff8880773478e0
R13: ffffffff8c79dad0 R14: ffff8880773478c0 R15: ffffc9000f327ce0
 ____sys_recvmsg+0x3aa/0x460 net/socket.c:2848
 ___sys_recvmsg+0x1b5/0x510 net/socket.c:2892
 do_recvmmsg+0x307/0x770 net/socket.c:2987
 __sys_recvmmsg net/socket.c:3061 [inline]
 __do_sys_recvmmsg net/socket.c:3084 [inline]
 __se_sys_recvmmsg net/socket.c:3077 [inline]
 __x64_sys_recvmmsg+0x190/0x240 net/socket.c:3077
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f2a0a98f749
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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f2a0b8e3038 EFLAGS: 00000246 ORIG_RAX: 000000000000012b
RAX: ffffffffffffffda RBX: 00007f2a0abe6090 RCX: 00007f2a0a98f749
RDX: 0000000000010106 RSI: 00002000000000c0 RDI: 0000000000000004
RBP: 00007f2a0aa13f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000002 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f2a0abe6128 R14: 00007f2a0abe6090 R15: 00007f2a0ad0fa28
 </TASK>
task:syz.8.5491      state:R  running task     stack:24936 pid:14225 tgid:14225 ppid:27827  task_flags:0x400040 flags:0x00080003
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5325 [inline]
 __schedule+0x1798/0x4cc0 kernel/sched/core.c:6929
 preempt_schedule_common+0x83/0xd0 kernel/sched/core.c:7113
 preempt_schedule+0xae/0xc0 kernel/sched/core.c:7137
 preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12
 __raw_spin_unlock include/linux/spinlock_api_smp.h:143 [inline]
 _raw_spin_unlock+0x3f/0x50 kernel/locking/spinlock.c:186
 spin_unlock include/linux/spinlock.h:391 [inline]
 insert_page+0x189/0x2c0 mm/memory.c:2333
 kcov_mmap+0xc2/0x120 kernel/kcov.c:506
 vfs_mmap include/linux/fs.h:2465 [inline]
 mmap_file mm/internal.h:167 [inline]
 __mmap_new_file_vma mm/vma.c:2413 [inline]
 __mmap_new_vma mm/vma.c:2476 [inline]
 __mmap_region mm/vma.c:2670 [inline]
 mmap_region+0x18b4/0x2110 mm/vma.c:2740
 do_mmap+0xc45/0x10d0 mm/mmap.c:558
 vm_mmap_pgoff+0x2a6/0x4d0 mm/util.c:581
 ksys_mmap_pgoff+0x51f/0x760 mm/mmap.c:604
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f44c7d8f783
RSP: 002b:00007f44c810fae8 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007f44c7fe6308 RCX: 00007f44c7d8f783
RDX: 0000000000000003 RSI: 0000000000400000 RDI: 00007f44c5bf6000
RBP: 00007f44c7fe6270 R08: 00000000000000db R09: 0000000000000000
R10: 0000000000000011 R11: 0000000000000246 R12: 0000000000000003
R13: 00007f44c7fe6270 R14: 0000000000000ef4 R15: 0000000000000003
 </TASK>
task:udevd           state:R  running task     stack:24328 pid:22708 tgid:22708 ppid:5200   task_flags:0x400140 flags:0x00080001
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5325 [inline]
 __schedule+0x1798/0x4cc0 kernel/sched/core.c:6929
 preempt_schedule_common+0x83/0xd0 kernel/sched/core.c:7113
 preempt_schedule+0xae/0xc0 kernel/sched/core.c:7137
 preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12
 __raw_spin_unlock include/linux/spinlock_api_smp.h:143 [inline]
 _raw_spin_unlock+0x3f/0x50 kernel/locking/spinlock.c:186
 spin_unlock include/linux/spinlock.h:391 [inline]
 wp_page_copy mm/memory.c:3781 [inline]
 do_wp_page+0x1d1d/0x5800 mm/memory.c:4141
 handle_pte_fault mm/memory.c:6211 [inline]
 __handle_mm_fault+0x1033/0x5400 mm/memory.c:6336
 handle_mm_fault+0x40a/0x8e0 mm/memory.c:6505
 do_user_addr_fault+0xa7c/0x1380 arch/x86/mm/fault.c:1336
 handle_page_fault arch/x86/mm/fault.c:1476 [inline]
 exc_page_fault+0x82/0x100 arch/x86/mm/fault.c:1532
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618
RIP: 0033:0x7fcc0a4b5b69
RSP: 002b:00007ffe9b49b020 EFLAGS: 00010202
RAX: 00007fcc0a5f2260 RBX: 0000000000007f30 RCX: 000056343438af00
RDX: 000056343438af00 RSI: 00007fcc0a5f2260 RDI: 000056343438af00
RBP: 00007fcc0a5f1ac0 R08: 0000000000007f30 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000563434386540
R13: 00007fcc0a5f1ac0 R14: 0000000000007f30 R15: 00007fcc0a5f1ac0
 </TASK>
rcu: rcu_preempt kthread timer wakeup didn't happen for 10501 jiffies! g213257 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=1 timer-softirq=131246
rcu: rcu_preempt kthread starved for 10502 jiffies! g213257 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=1
rcu: 	Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt     state:I stack:27224 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5325 [inline]
 __schedule+0x1798/0x4cc0 kernel/sched/core.c:6929
 __schedule_loop kernel/sched/core.c:7011 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:7026
 schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x301/0x1540 kernel/rcu/tree.c:2083
 rcu_gp_kthread+0x99/0x390 kernel/rcu/tree.c:2285
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>