syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-...!: (0 ticks this GP) idle=dbdc/1/0x4000000000000000 softirq=171973/171973 fqs=0
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P21620
rcu: 	(detected by 1, t=10506 jiffies, g=152973, q=470 ncpus=2)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 21620 Comm: syz-executor Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:_raw_spin_lock+0x32/0x40 kernel/locking/spinlock.c:159
Code: bf 01 00 00 00 e8 de be 47 f6 ff 74 24 08 48 8d 7b 18 45 31 c9 31 c9 41 b8 01 00 00 00 31 d2 31 f6 e8 b2 35 57 f6 48 89 df 58 <5b> e9 f8 86 57 f6 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90
RSP: 0018:ffffc90000007dc8 EFLAGS: 00000086
RAX: ffffffff899bb3e5 RBX: ffff8880551412a8 RCX: 0000000000000004
RDX: 0000000000000000 RSI: ffffffff8defba11 RDI: ffff8880551412a8
RBP: ffff88802d852000 R08: 000000001d03d2a9 R09: 0000000000000f32
R10: 0000000000000000 R11: 0000000000000001 R12: ffff888055141300
R13: ffff88804c2dd578 R14: dffffc0000000000 R15: ffff8880b8428650
FS:  0000555562b24500(0000) GS:ffff888124373000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f76349e8158 CR3: 000000008feaa000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 spin_lock include/linux/spinlock.h:342 [inline]
 advance_sched+0xe5/0xd20 net/sched/sch_taprio.c:930
 __run_hrtimer kernel/time/hrtimer.c:1930 [inline]
 __hrtimer_run_queues+0x470/0xa00 kernel/time/hrtimer.c:1994
 hrtimer_interrupt+0x3e5/0x940 kernel/time/hrtimer.c:2113
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline]
 __sysvec_apic_timer_interrupt+0x10b/0x460 arch/x86/kernel/apic/apic.c:1067
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1061 [inline]
 sysvec_apic_timer_interrupt+0x9e/0xc0 arch/x86/kernel/apic/apic.c:1061
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:finish_task_switch.isra.0+0x2d3/0x1010 kernel/sched/core.c:5245
Code: 2f 0a 00 00 41 c7 87 e0 0d 00 00 00 00 00 00 e9 0f 04 00 00 49 8d 7f 48 e8 2a fd b7 09 e8 65 92 3b 00 fb 48 8d bb a8 16 00 00 <48> b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 0f b6 04 02 84
RSP: 0018:ffffc900079e72f0 EFLAGS: 00000202
RAX: 0000000000399c91 RBX: ffff88804c2dca00 RCX: 0000000000000040
RDX: 0000000000000000 RSI: ffffffff8df20f3b RDI: ffff88804c2de0a8
RBP: ffffc900079e7348 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: ffffffff8e4955c0
R13: 0000000000000001 R14: ffffffff90d7dce4 R15: ffff8880b843b240
 context_switch kernel/sched/core.c:5391 [inline]
 __schedule+0x10f1/0x6820 kernel/sched/core.c:7189
 preempt_schedule_common+0x42/0xc0 kernel/sched/core.c:7370
 preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12
 __raw_spin_unlock include/linux/spinlock_api_smp.h:169 [inline]
 _raw_spin_unlock+0x3e/0x50 kernel/locking/spinlock.c:190
 spin_unlock include/linux/spinlock.h:390 [inline]
 copy_pte_range mm/memory.c:1331 [inline]
 copy_pmd_range mm/memory.c:1392 [inline]
 copy_pud_range mm/memory.c:1429 [inline]
 copy_p4d_range mm/memory.c:1453 [inline]
 copy_page_range+0x1c02/0x5b00 mm/memory.c:1539
 dup_mmap+0xd25/0x2180 mm/mmap.c:1840
 dup_mm kernel/fork.c:1534 [inline]
 copy_mm kernel/fork.c:1586 [inline]
 copy_process+0x6c63/0x7e00 kernel/fork.c:2264
 kernel_clone+0x12e/0x9c0 kernel/fork.c:2721
 __do_sys_clone+0xd9/0x120 kernel/fork.c:2862
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x10b/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f47169c5852
Code: 89 e7 e8 71 8b f7 ff 45 31 c0 31 d2 31 f6 64 48 8b 04 25 10 00 00 00 bf 11 00 20 01 4c 8d 90 d0 02 00 00 b8 38 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 66 89 c5 85 c0 75 3b 64 48 8b 04 25 10 00 00
RSP: 002b:00007ffffebeb100 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 00007ffffebeb100 RCX: 00007f47169c5852
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011
RBP: 00007ffffebeb28c R08: 0000000000000000 R09: 0000000000000001
R10: 0000555562b247d0 R11: 0000000000000246 R12: 0000000000000001
R13: 00000000000927c0 R14: 00000000001e1d2a R15: 00007ffffebeb2e0
 </TASK>
task:syz-executor    state:R  running task     stack:22936 pid:21620 tgid:21620 ppid:21604  task_flags:0x400140 flags:0x00080010
Call Trace:
 <TASK>
 </TASK>
rcu: rcu_preempt kthread starved for 10506 jiffies! g152973 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->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:R  running task     stack:26712 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5388 [inline]
 __schedule+0x10e9/0x6820 kernel/sched/core.c:7189
 __schedule_loop kernel/sched/core.c:7268 [inline]
 schedule+0xdd/0x390 kernel/sched/core.c:7283
 schedule_timeout+0x127/0x280 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x1a9/0x900 kernel/rcu/tree.c:2095
 rcu_gp_kthread+0x179/0x230 kernel/rcu/tree.c:2297
 kthread+0x370/0x450 kernel/kthread.c:436
 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 1 UID: 0 PID: 12073 Comm: syz-executor Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline]
RIP: 0010:smp_call_function_many_cond+0x589/0x1700 kernel/smp.c:892
Code: b8 00 00 00 00 00 fc ff df 48 8b 54 24 08 49 89 d5 49 89 d4 49 c1 ed 03 41 83 e4 07 49 01 c5 41 83 c4 03 e8 79 83 0c 00 f3 90 <41> 0f b6 45 00 41 38 c4 7c 08 84 c0 0f 85 63 0f 00 00 8b 45 08 31
RSP: 0018:ffffc90003b77620 EFLAGS: 00000293
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff81fc0fcd
RDX: ffff888022bdca00 RSI: ffffffff81fc0fa7 RDI: ffff888022bdca00
RBP: ffff8880b8443320 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000003
R13: ffffed1017088665 R14: 0000000000000001 R15: ffff8880b853c5c0
FS:  00005555775f3500(0000) GS:ffff888124473000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fa2713456b8 CR3: 000000007a624000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 on_each_cpu_cond_mask+0x40/0x90 kernel/smp.c:1057
 __flush_tlb_multi arch/x86/include/asm/paravirt.h:46 [inline]
 flush_tlb_multi arch/x86/mm/tlb.c:1361 [inline]
 flush_tlb_mm_range+0x45f/0x16f0 arch/x86/mm/tlb.c:1451
 dup_mmap+0x12e8/0x2180 mm/mmap.c:1905
 dup_mm kernel/fork.c:1534 [inline]
 copy_mm kernel/fork.c:1586 [inline]
 copy_process+0x6c63/0x7e00 kernel/fork.c:2264
 kernel_clone+0x12e/0x9c0 kernel/fork.c:2721
 __do_sys_clone+0xd9/0x120 kernel/fork.c:2862
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x10b/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fa2705c5852
Code: 89 e7 e8 71 8b f7 ff 45 31 c0 31 d2 31 f6 64 48 8b 04 25 10 00 00 00 bf 11 00 20 01 4c 8d 90 d0 02 00 00 b8 38 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 66 89 c5 85 c0 75 3b 64 48 8b 04 25 10 00 00
RSP: 002b:00007ffcb295e360 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 00007ffcb295e360 RCX: 00007fa2705c5852
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011
RBP: 00007ffcb295e4ec R08: 0000000000000000 R09: 0000000000000001
R10: 00005555775f37d0 R11: 0000000000000246 R12: 0000000000000001
R13: 00000000000927c0 R14: 00000000001e1d9d R15: 00007ffcb295e540
 </TASK>