syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	1-...!: (8 ticks this GP) idle=fe74/1/0x4000000000000000 softirq=48967/48967 fqs=6
rcu: 	(detected by 0, t=10502 jiffies, g=44929, q=86 ncpus=2)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 12772 Comm: syz.5.1976 Not tainted 6.16.0-rc3-syzkaller-00233-g35e261cd95dd #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:__lock_acquire+0xcb0/0xd20 kernel/locking/lockdep.c:5273
Code: f8 ad 8d e8 32 59 89 ff 48 89 df e8 ba 2d 89 ff e8 25 2c 89 ff e8 50 b9 94 ff e8 cb 8e 03 00 45 31 ff 44 89 f8 48 83 c4 30 5b <41> 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc cc 89 05 83 46 03 12 e9
RSP: 0018:ffffc90000a08b68 EFLAGS: 00000086
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 4bddbc75e6dc3a00
RDX: 0000000000000000 RSI: ffff88802946a940 RDI: ffff888029469e00
RBP: 0000000000000001 R08: 0000000000000000 R09: ffffffff897f71a4
R10: dffffc0000000000 R11: ffffffff897f70e0 R12: 0000000000000c94
R13: ffff88802946a8f0 R14: ffff88802946a940 R15: 0000000000000001
FS:  00007f64f0f826c0(0000) GS:ffff888125d84000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c2a792a CR3: 000000002fcd2000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5871
 __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]
 advance_sched+0xc4/0xc90 net/sched/sch_taprio.c:924
 __run_hrtimer kernel/time/hrtimer.c:1761 [inline]
 __hrtimer_run_queues+0x529/0xc60 kernel/time/hrtimer.c:1825
 hrtimer_interrupt+0x45b/0xaa0 kernel/time/hrtimer.c:1887
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1039 [inline]
 __sysvec_apic_timer_interrupt+0x10b/0x410 arch/x86/kernel/apic/apic.c:1056
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline]
 sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1050
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:lockdep_enabled kernel/locking/lockdep.c:124 [inline]
RIP: 0010:lock_release+0x81/0x3e0 kernel/locking/lockdep.c:5884
Code: 84 ad 02 00 00 83 3d 1d df 01 0e 00 0f 84 44 02 00 00 65 8b 05 20 ce fb 10 85 c0 0f 85 35 02 00 00 65 4c 8b 3c 25 08 c0 99 92 <41> 83 bf ec 0a 00 00 00 0f 85 1e 02 00 00 49 81 3e 40 73 5d 93 0f
RSP: 0018:ffffc9000fa97758 EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffffffff8209e3cf RCX: 4bddbc75e6dc3a00
RDX: ffffc9001c8b3000 RSI: ffffffff8be1bb60 RDI: ffffffff8be1bb20
RBP: ffffc9000fa979a8 R08: ffffffff8f9fdff7 R09: 1ffffffff1f3fbfe
R10: dffffc0000000000 R11: fffffbfff1f3fbff R12: ffffffff8b94c5b8
R13: ffffffff8209e3cf R14: ffffffff8e13ee60 R15: ffff888029469e00
 rcu_lock_release include/linux/rcupdate.h:341 [inline]
 rcu_read_unlock include/linux/rcupdate.h:871 [inline]
 do_fault_around mm/memory.c:5551 [inline]
 do_read_fault mm/memory.c:5581 [inline]
 do_fault mm/memory.c:5724 [inline]
 do_pte_missing mm/memory.c:4251 [inline]
 handle_pte_fault mm/memory.c:6069 [inline]
 __handle_mm_fault+0x374e/0x5620 mm/memory.c:6212
 handle_mm_fault+0x2d5/0x7f0 mm/memory.c:6381
 faultin_page mm/gup.c:1186 [inline]
 __get_user_pages+0x1af4/0x30b0 mm/gup.c:1488
 populate_vma_page_range+0x26b/0x340 mm/gup.c:1926
 __mm_populate+0x24c/0x380 mm/gup.c:2029
 mm_populate include/linux/mm.h:3348 [inline]
 vm_mmap_pgoff+0x3f0/0x4c0 mm/util.c:584
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f64f018e929
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:00007f64f0f82038 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007f64f03b5fa0 RCX: 00007f64f018e929
RDX: b635773f06ebbeee RSI: 0000000000b36000 RDI: 0000200000000000
RBP: 00007f64f0210b39 R08: ffffffffffffffff R09: 0000000000000000
R10: 0000000000008031 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f64f03b5fa0 R15: 00007ffef58a4508
 </TASK>
rcu: rcu_preempt kthread starved for 10490 jiffies! g44929 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
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:27192 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5396 [inline]
 __schedule+0x16a2/0x4cb0 kernel/sched/core.c:6785
 __schedule_loop kernel/sched/core.c:6863 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:6878
 schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x301/0x1540 kernel/rcu/tree.c:2054
 rcu_gp_kthread+0x99/0x390 kernel/rcu/tree.c:2256
 kthread+0x70e/0x8a0 kernel/kthread.c:464
 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 UID: 0 PID: 12777 Comm: syz.0.1975 Not tainted 6.16.0-rc3-syzkaller-00233-g35e261cd95dd #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:csd_lock_wait kernel/smp.c:340 [inline]
RIP: 0010:smp_call_function_many_cond+0xf69/0x12d0 kernel/smp.c:885
Code: 00 45 8b 2f 44 89 ee 83 e6 01 31 ff e8 b0 79 0b 00 41 83 e5 01 49 bd 00 00 00 00 00 fc ff df 75 07 e8 5b 75 0b 00 eb 37 f3 90 <43> 0f b6 04 2c 84 c0 75 10 41 f7 07 01 00 00 00 74 1e e8 40 75 0b
RSP: 0018:ffffc9000dd77360 EFLAGS: 00000293
RAX: ffffffff81b4d830 RBX: ffff8880b863b040 RCX: ffff888025a5bc00
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc9000dd774c0 R08: ffffffff8f9fdff7 R09: 1ffffffff1f3fbfe
R10: dffffc0000000000 R11: fffffbfff1f3fbff R12: 1ffff110170e7f2d
R13: dffffc0000000000 R14: 0000000000000001 R15: ffff8880b873f968
FS:  0000000000000000(0000) GS:ffff888125c84000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005558b418b008 CR3: 000000000df38000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1052
 __flush_tlb_multi arch/x86/include/asm/paravirt.h:91 [inline]
 flush_tlb_multi arch/x86/mm/tlb.c:1361 [inline]
 flush_tlb_mm_range+0x6b1/0x12c0 arch/x86/mm/tlb.c:1451
 tlb_flush arch/x86/include/asm/tlb.h:23 [inline]
 tlb_flush_mmu_tlbonly include/asm-generic/tlb.h:490 [inline]
 tlb_flush_mmu+0x1a7/0x680 mm/mmu_gather.c:403
 tlb_finish_mmu+0xc3/0x1d0 mm/mmu_gather.c:497
 free_ldt_pgtables+0x17b/0x320 arch/x86/kernel/ldt.c:411
 arch_exit_mmap arch/x86/include/asm/mmu_context.h:234 [inline]
 exit_mmap+0x17c/0xb50 mm/mmap.c:1270
 __mmput+0x118/0x420 kernel/fork.c:1121
 exit_mm+0x1da/0x2c0 kernel/exit.c:581
 do_exit+0x648/0x22e0 kernel/exit.c:952
 do_group_exit+0x21c/0x2d0 kernel/exit.c:1105
 get_signal+0x125e/0x1310 kernel/signal.c:3034
 arch_do_signal_or_restart+0x9a/0x750 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop+0x75/0x110 kernel/entry/common.c:111
 exit_to_user_mode_prepare include/linux/entry-common.h:330 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:414 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:449 [inline]
 do_syscall_64+0x2bd/0x3b0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f60c4b8e929
Code: Unable to access opcode bytes at 0x7f60c4b8e8ff.
RSP: 002b:00007f60c29f60e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: 0000000000000001 RBX: 00007f60c4db5fa8 RCX: 00007f60c4b8e929
RDX: 00000000000f4240 RSI: 0000000000000081 RDI: 00007f60c4db5fac
RBP: 00007f60c4db5fa0 R08: 7fffffffffffffff R09: 0000000000000000
R10: 0000000000000030 R11: 0000000000000246 R12: 00007f60c4db5fac
R13: 0000000000000000 R14: 00007ffc1c49b010 R15: 00007ffc1c49b0f8
 </TASK>