syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-...0: (2 GPs behind) idle=d06c/0/0x1 softirq=15720/15720 fqs=1146
rcu: 	         hardirqs   softirqs   csw/system
rcu: 	 number:        0          0            0
rcu: 	cputime:        0          0            0   ==> 52500(ms)
rcu: 	(detected by 1, t=10503 jiffies, g=9177, q=296 ncpus=2)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.16.0-rc5-syzkaller-00266-g3f31a806a62e #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:its_return_thunk+0x0/0x10 arch/x86/lib/retpoline.S:412
Code: cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc <c3> cc 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 e9 5b bc a0 f5 cc
RSP: 0018:ffffc90000007d40 EFLAGS: 00000086
RAX: 0000000000000000 RBX: ffffffff8e5c4dc0 RCX: ffffc90000007d54
RDX: 0000000000000000 RSI: ffffffff8de0d97d RDI: ffffffff8c158f60
RBP: ffff888069ff4800 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: ffffffff899ade5c
R13: 0000000000000006 R14: ffffffff8e297780 R15: 0000000000000001
FS:  0000000000000000(0000) GS:ffff888124713000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fe065a7cb30 CR3: 00000000341e3000 CR4: 00000000003526f0
Call Trace:
 <IRQ>
 lockdep_recursion_finish kernel/locking/lockdep.c:473 [inline]
 lock_release+0x153/0x2f0 kernel/locking/lockdep.c:5894
 rcu_lock_release include/linux/rcupdate.h:341 [inline]
 rcu_read_unlock include/linux/rcupdate.h:871 [inline]
 advance_sched+0x6f1/0xc80 net/sched/sch_taprio.c:987
 __run_hrtimer kernel/time/hrtimer.c:1761 [inline]
 __hrtimer_run_queues+0x1ff/0xad0 kernel/time/hrtimer.c:1825
 hrtimer_interrupt+0x397/0x8e0 kernel/time/hrtimer.c:1887
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1039 [inline]
 __sysvec_apic_timer_interrupt+0x10b/0x3f0 arch/x86/kernel/apic/apic.c:1056
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline]
 sysvec_apic_timer_interrupt+0x9f/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:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:82
Code: cb 6b 02 e9 83 fb 02 00 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d e3 b8 21 00 fb f4 <c3> cc cc cc cc 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 90 90 90
RSP: 0018:ffffffff8e207e08 EFLAGS: 000002c6
RAX: 00000000000c4913 RBX: 0000000000000000 RCX: ffffffff8b885c99
RDX: 0000000000000000 RSI: ffffffff8de32e47 RDI: ffffffff8c158f60
RBP: fffffbfff1c52ef0 R08: 0000000000000001 R09: ffffed1017086645
R10: ffff8880b843322b R11: 0000000000000001 R12: 0000000000000000
R13: ffffffff8e297780 R14: ffffffff90a98650 R15: 0000000000000000
 arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline]
 default_idle+0x13/0x20 arch/x86/kernel/process.c:749
 default_idle_call+0x6d/0xb0 kernel/sched/idle.c:117
 cpuidle_idle_call kernel/sched/idle.c:185 [inline]
 do_idle+0x391/0x510 kernel/sched/idle.c:325
 cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:423
 rest_init+0x16b/0x2b0 init/main.c:745
 start_kernel+0x3ee/0x4d0 init/main.c:1102
 x86_64_start_reservations+0x18/0x30 arch/x86/kernel/head64.c:307
 x86_64_start_kernel+0x130/0x190 arch/x86/kernel/head64.c:288
 common_startup_64+0x13e/0x148
 </TASK>
rcu: rcu_preempt kthread starved for 4775 jiffies! g9177 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:27272 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5397 [inline]
 __schedule+0x116a/0x5de0 kernel/sched/core.c:6786
 __schedule_loop kernel/sched/core.c:6864 [inline]
 schedule+0xe7/0x3a0 kernel/sched/core.c:6879
 schedule_timeout+0x123/0x290 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x1ea/0xb00 kernel/rcu/tree.c:2054
 rcu_gp_kthread+0x270/0x380 kernel/rcu/tree.c:2256
 kthread+0x3c5/0x780 kernel/kthread.c:464
 ret_from_fork+0x5d7/0x6f0 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: 1 UID: 0 PID: 5497 Comm: dhcpcd Not tainted 6.16.0-rc5-syzkaller-00266-g3f31a806a62e #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:__sanitizer_cov_trace_const_cmp4+0xc/0x20 kernel/kcov.c:314
Code: 00 e9 58 fe ff ff 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 48 8b 0c 24 89 f2 89 fe <bf> 05 00 00 00 e9 2a fe ff ff 66 2e 0f 1f 84 00 00 00 00 00 90 90
RSP: 0018:ffffc90003537748 EFLAGS: 00000202
RAX: 0000000000000001 RBX: ffff8880b84421e0 RCX: ffffffff81afd49d
RDX: 0000000000000001 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000001 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: dffffc0000000000
R13: 0000000000000003 R14: ffffed101708843d R15: ffff8880b853b580
FS:  00007f292fbc3740(0000) GS:ffff888124813000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffce21ee000 CR3: 0000000033193000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 csd_lock_wait kernel/smp.c:340 [inline]
 smp_call_function_many_cond+0xd9d/0x1510 kernel/smp.c:885
 on_each_cpu_cond_mask+0x40/0x90 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+0x4a0/0x1790 arch/x86/mm/tlb.c:1451
 dup_mmap+0xfa2/0x21d0 mm/mmap.c:1877
 dup_mm kernel/fork.c:1477 [inline]
 copy_mm kernel/fork.c:1529 [inline]
 copy_process+0x4081/0x7650 kernel/fork.c:2169
 kernel_clone+0xfc/0x960 kernel/fork.c:2599
 __do_sys_clone+0xce/0x120 kernel/fork.c:2742
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f292fc97636
Code: 89 df e8 6d e8 f6 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 52 89 c5 85 c0 75 31 64 48 8b 04 25 10 00 00
RSP: 002b:00007fff3fbc8ac0 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 00007fff3fbc8ac8 RCX: 00007f292fc97636
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011
RBP: 00007fff3fbe9010 R08: 0000000000000000 R09: 0000000000000001
R10: 00007f292fbc3a10 R11: 0000000000000246 R12: 00007fff3fbc8c00
R13: 0000000000000000 R14: 0000000000000000 R15: 000055c1170b7ac0
 </TASK>