rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 0-...!: (1 GPs behind) idle=2df/1/0x4000000000000000 softirq=257376/257377 fqs=1 (detected by 1, t=10502 jiffies, g=462553, q=134) Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 26900 Comm: syz-executor.3 Not tainted 5.15.0-rc1-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:lock_acquire kernel/locking/lockdep.c:5625 [inline] RIP: 0010:lock_acquire+0x19a/0x510 kernel/locking/lockdep.c:5590 Code: 41 89 e8 44 89 e1 44 89 ea 65 ff 05 00 93 a6 7e 48 81 64 24 08 00 02 00 00 44 89 fe 6a 00 4c 89 f7 6a 00 ff b4 24 f8 00 00 00 74 24 18 41 0f 94 c1 45 0f b6 c9 e8 d5 96 ff ff 48 c7 c7 c0 fb RSP: 0018:ffffc90000007a50 EFLAGS: 00000046 RAX: 0000000000000000 RBX: 1ffff92000000f4f RCX: 0000000000000002 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8b97fe20 RBP: 0000000000000000 R08: 0000000000000000 R09: ffff8880b9c32a0b R10: ffffed1017386541 R11: 0000000000000000 R12: 0000000000000002 R13: 0000000000000000 R14: ffffffff8b97fe20 R15: 0000000000000000 FS: 00007fd5405d0700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b2eb25000 CR3: 000000007dec5000 CR4: 00000000001506f0 Call Trace: rcu_lock_acquire include/linux/rcupdate.h:267 [inline] rcu_read_lock include/linux/rcupdate.h:687 [inline] advance_sched+0x4a5/0x9a0 net/sched/sch_taprio.c:763 __run_hrtimer kernel/time/hrtimer.c:1685 [inline] __hrtimer_run_queues+0x609/0xe50 kernel/time/hrtimer.c:1749 hrtimer_interrupt+0x31c/0x790 kernel/time/hrtimer.c:1811 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1086 [inline] __sysvec_apic_timer_interrupt+0x146/0x530 arch/x86/kernel/apic/apic.c:1103 sysvec_apic_timer_interrupt+0x40/0xc0 arch/x86/kernel/apic/apic.c:1097 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638 RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline] RIP: 0010:_raw_spin_unlock_irqrestore+0x38/0x70 kernel/locking/spinlock.c:194 Code: 74 24 10 e8 ba ec 23 f8 48 89 ef e8 02 63 24 f8 81 e3 00 02 00 00 75 25 9c 58 f6 c4 02 75 2d 48 85 db 74 01 fb bf 01 00 00 00 b3 23 18 f8 65 8b 05 ac 7d ca 76 85 c0 74 0a 5b 5d c3 e8 10 c5 RSP: 0018:ffffc90000007e48 EFLAGS: 00000206 RAX: 0000000000000006 RBX: 0000000000000200 RCX: 1ffffffff1fa0e8a RDX: 0000000000000000 RSI: 0000000000000102 RDI: 0000000000000001 RBP: ffff8880b9c223c0 R08: 0000000000000001 R09: ffffffff8fcfa947 R10: 0000000000000001 R11: 0000000000000000 R12: 0000025bc147bfa2 R13: ffff8880b9c22640 R14: ffff8880b9c223c0 R15: ffffffff853655e0 __run_hrtimer kernel/time/hrtimer.c:1681 [inline] __hrtimer_run_queues+0x51a/0xe50 kernel/time/hrtimer.c:1749 hrtimer_run_softirq+0x17b/0x360 kernel/time/hrtimer.c:1766 __do_softirq+0x29b/0x9c2 kernel/softirq.c:558 do_softirq.part.0+0xde/0x130 kernel/softirq.c:459 do_softirq kernel/softirq.c:451 [inline] __local_bh_enable_ip+0x102/0x120 kernel/softirq.c:383 spin_unlock_bh include/linux/spinlock.h:408 [inline] taprio_change+0x290f/0x4160 net/sched/sch_taprio.c:1609 taprio_init+0x52e/0x670 net/sched/sch_taprio.c:1727 qdisc_create+0x475/0x1320 net/sched/sch_api.c:1247 tc_modify_qdisc+0x4c8/0x1a60 net/sched/sch_api.c:1663 rtnetlink_rcv_msg+0x413/0xb80 net/core/rtnetlink.c:5572 netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2504 netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline] netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1340 netlink_sendmsg+0x86d/0xdb0 net/netlink/af_netlink.c:1929 sock_sendmsg_nosec net/socket.c:704 [inline] sock_sendmsg+0xcf/0x120 net/socket.c:724 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2409 ___sys_sendmsg+0xf3/0x170 net/socket.c:2463 __sys_sendmsg+0xf3/0x1c0 net/socket.c:2492 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7fd54307a739 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 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fd5405d0188 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007fd54317f038 RCX: 00007fd54307a739 RDX: 0000000000000000 RSI: 00000000200007c0 RDI: 0000000000000009 RBP: 00007fd5430d4cc4 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007fd54317f038 R13: 00007fd5436b2b1f R14: 00007fd5405d0300 R15: 0000000000022000 rcu: rcu_preempt kthread timer wakeup didn't happen for 10479 jiffies! g462553 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 rcu: Possible timer handling issue on cpu=1 timer-softirq=218765 rcu: rcu_preempt kthread starved for 10480 jiffies! g462553 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:28696 pid: 14 ppid: 2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:4940 [inline] __schedule+0x940/0x26f0 kernel/sched/core.c:6287 schedule+0xd3/0x270 kernel/sched/core.c:6366 schedule_timeout+0x14a/0x2a0 kernel/time/timer.c:1881 rcu_gp_fqs_loop+0x186/0x800 kernel/rcu/tree.c:1957 rcu_gp_kthread+0x1de/0x320 kernel/rcu/tree.c:2130 kthread+0x3e5/0x4d0 kernel/kthread.c:319 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 rcu: Stack dump where RCU GP kthread last ran: NMI backtrace for cpu 1 CPU: 1 PID: 8635 Comm: kworker/u4:3 Not tainted 5.15.0-rc1-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: writeback wb_workfn (flush-8:0) Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 nmi_cpu_backtrace.cold+0x47/0x144 lib/nmi_backtrace.c:105 nmi_trigger_cpumask_backtrace+0x1ae/0x220 lib/nmi_backtrace.c:62 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline] rcu_check_gp_kthread_starvation.cold+0x1fb/0x200 kernel/rcu/tree_stall.h:481 print_other_cpu_stall kernel/rcu/tree_stall.h:586 [inline] check_cpu_stall kernel/rcu/tree_stall.h:729 [inline] rcu_pending kernel/rcu/tree.c:3880 [inline] rcu_sched_clock_irq+0x2125/0x2200 kernel/rcu/tree.c:2599 update_process_times+0x16d/0x200 kernel/time/timer.c:1785 tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:226 tick_sched_timer+0x1b0/0x2d0 kernel/time/tick-sched.c:1421 __run_hrtimer kernel/time/hrtimer.c:1685 [inline] __hrtimer_run_queues+0x1c0/0xe50 kernel/time/hrtimer.c:1749 hrtimer_interrupt+0x31c/0x790 kernel/time/hrtimer.c:1811 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1086 [inline] __sysvec_apic_timer_interrupt+0x146/0x530 arch/x86/kernel/apic/apic.c:1103 sysvec_apic_timer_interrupt+0x8e/0xc0 arch/x86/kernel/apic/apic.c:1097 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638 RIP: 0010:write_comp_data kernel/kcov.c:218 [inline] RIP: 0010:__sanitizer_cov_trace_const_cmp4+0x17/0x70 kernel/kcov.c:284 Code: 30 f0 4c 89 54 d8 20 48 89 10 5b c3 0f 1f 80 00 00 00 00 41 89 f8 bf 03 00 00 00 4c 8b 14 24 89 f1 65 48 8b 34 25 40 f0 01 00 54 f0 ff ff 84 c0 74 4b 48 8b 86 20 15 00 00 8b b6 1c 15 00 00 RSP: 0018:ffffc9001779ecb8 EFLAGS: 00000202 RAX: 0000000000000001 RBX: ffff8880b9c39ce0 RCX: 0000000000000001 RDX: ffff88803897b900 RSI: ffff88803897b900 RDI: 0000000000000003 RBP: 0000000000000003 R08: 0000000000000000 R09: 0000000000000000 R10: ffffffff816ac5c6 R11: 0000000000000000 R12: ffffed101738739d R13: 0000000000000000 R14: ffff8880b9c39ce8 R15: 0000000000000001 csd_lock_wait kernel/smp.c:440 [inline] smp_call_function_many_cond+0x476/0xc20 kernel/smp.c:969 on_each_cpu_cond_mask+0x56/0xa0 kernel/smp.c:1135 __flush_tlb_multi arch/x86/include/asm/paravirt.h:87 [inline] flush_tlb_multi arch/x86/mm/tlb.c:927 [inline] flush_tlb_mm_range+0x1d8/0x230 arch/x86/mm/tlb.c:1013 flush_tlb_page arch/x86/include/asm/tlbflush.h:239 [inline] ptep_clear_flush+0x12b/0x160 mm/pgtable-generic.c:97 page_mkclean_one+0x4ce/0x8c0 mm/rmap.c:935 rmap_walk_file+0x3a5/0x6e0 mm/rmap.c:2352 rmap_walk+0x10d/0x190 mm/rmap.c:2370 page_mkclean+0x222/0x2c0 mm/rmap.c:1003 clear_page_dirty_for_io+0x325/0xa70 mm/page-writeback.c:2727 mpage_submit_page+0x80/0x2a0 fs/ext4/inode.c:2086 mpage_process_page_bufs+0x681/0x7a0 fs/ext4/inode.c:2220 mpage_prepare_extent_to_map+0x945/0xe50 fs/ext4/inode.c:2632 ext4_writepages+0x928/0x3ba0 fs/ext4/inode.c:2760 do_writepages+0x1ab/0x7b0 mm/page-writeback.c:2364 __writeback_single_inode+0x126/0xff0 fs/fs-writeback.c:1616 writeback_sb_inodes+0x53d/0xf00 fs/fs-writeback.c:1881 __writeback_inodes_wb+0xc6/0x280 fs/fs-writeback.c:1950 wb_writeback+0x7f8/0xc30 fs/fs-writeback.c:2055 wb_check_old_data_flush fs/fs-writeback.c:2155 [inline] wb_do_writeback fs/fs-writeback.c:2208 [inline] wb_workfn+0x8cf/0x12d0 fs/fs-writeback.c:2237 process_one_work+0x9bf/0x16b0 kernel/workqueue.c:2297 worker_thread+0x658/0x11f0 kernel/workqueue.c:2444 kthread+0x3e5/0x4d0 kernel/kthread.c:319 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 ---------------- Code disassembly (best guess): 0: 41 89 e8 mov %ebp,%r8d 3: 44 89 e1 mov %r12d,%ecx 6: 44 89 ea mov %r13d,%edx 9: 65 ff 05 00 93 a6 7e incl %gs:0x7ea69300(%rip) # 0x7ea69310 10: 48 81 64 24 08 00 02 andq $0x200,0x8(%rsp) 17: 00 00 19: 44 89 fe mov %r15d,%esi 1c: 6a 00 pushq $0x0 1e: 4c 89 f7 mov %r14,%rdi 21: 6a 00 pushq $0x0 23: ff b4 24 f8 00 00 00 pushq 0xf8(%rsp) * 2a: ff 74 24 18 pushq 0x18(%rsp) <-- trapping instruction 2e: 41 0f 94 c1 sete %r9b 32: 45 0f b6 c9 movzbl %r9b,%r9d 36: e8 d5 96 ff ff callq 0xffff9710 3b: 48 rex.W 3c: c7 .byte 0xc7 3d: c7 .byte 0xc7 3e: c0 .byte 0xc0 3f: fb sti