rcu: INFO: rcu_preempt self-detected stall on CPU rcu: 1-...!: (10344 ticks this GP) idle=fa6/1/0x4000000000000000 softirq=113906/113940 fqs=1 (t=10500 jiffies g=208293 q=1713) rcu: rcu_preempt kthread starved for 10497 jiffies! g208293 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:28888 pid: 13 ppid: 2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:4313 [inline] __schedule+0x90c/0x21a0 kernel/sched/core.c:5064 schedule+0xcf/0x270 kernel/sched/core.c:5143 schedule_timeout+0x148/0x250 kernel/time/timer.c:1878 rcu_gp_fqs_loop kernel/rcu/tree.c:1940 [inline] rcu_gp_kthread+0xbbe/0x1d70 kernel/rcu/tree.c:2113 kthread+0x3b1/0x4a0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296 NMI backtrace for cpu 1 CPU: 1 PID: 8822 Comm: syz-executor.2 Not tainted 5.11.0-rc3-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:79 [inline] dump_stack+0x107/0x163 lib/dump_stack.c:120 nmi_cpu_backtrace.cold+0x44/0xd7 lib/nmi_backtrace.c:105 nmi_trigger_cpumask_backtrace+0x1b3/0x230 lib/nmi_backtrace.c:62 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline] rcu_dump_cpu_stacks+0x1f4/0x230 kernel/rcu/tree_stall.h:337 print_cpu_stall kernel/rcu/tree_stall.h:569 [inline] check_cpu_stall kernel/rcu/tree_stall.h:643 [inline] rcu_pending kernel/rcu/tree.c:3751 [inline] rcu_sched_clock_irq.cold+0x48e/0xedf kernel/rcu/tree.c:2580 update_process_times+0x16d/0x200 kernel/time/timer.c:1782 tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:226 tick_sched_timer+0x1b0/0x2d0 kernel/time/tick-sched.c:1369 __run_hrtimer kernel/time/hrtimer.c:1519 [inline] __hrtimer_run_queues+0x1c0/0xe40 kernel/time/hrtimer.c:1583 hrtimer_interrupt+0x334/0x940 kernel/time/hrtimer.c:1645 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1085 [inline] __sysvec_apic_timer_interrupt+0x146/0x540 arch/x86/kernel/apic/apic.c:1102 run_sysvec_on_irqstack_cond arch/x86/include/asm/irq_stack.h:91 [inline] sysvec_apic_timer_interrupt+0x48/0x100 arch/x86/kernel/apic/apic.c:1096 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:628 RIP: 0010:virtnet_poll_tx+0x56/0x370 drivers/net/virtio_net.c:1509 Code: 3c 02 00 0f 85 fd 02 00 00 49 8b 9c 24 48 fd ff ff 48 b8 00 00 00 00 00 fc ff df 48 8d 7b 20 48 89 fa 48 c1 ea 03 80 3c 02 00 <0f> 85 cc 02 00 00 48 b8 00 00 00 00 00 fc ff df 48 8b 6b 20 48 8d RSP: 0018:ffffc90000db0e40 EFLAGS: 00000246 RAX: dffffc0000000000 RBX: ffff888144911400 RCX: 0000000000000100 RDX: 1ffff11028922284 RSI: ffffffff84b0faea RDI: ffff888144911420 RBP: ffff88814499c6f8 R08: 0000000000000000 R09: 0000000000000001 R10: ffffffff86f8a9f4 R11: 0000000000000000 R12: ffff88814499c6f8 R13: ffff88814499c440 R14: dffffc0000000000 R15: ffff88814499c708 napi_poll net/core/dev.c:6805 [inline] net_rx_action+0x461/0xe10 net/core/dev.c:6888 __do_softirq+0x2bc/0xa29 kernel/softirq.c:343 asm_call_irq_on_stack+0xf/0x20 __run_on_irqstack arch/x86/include/asm/irq_stack.h:26 [inline] run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:77 [inline] do_softirq_own_stack+0xaa/0xd0 arch/x86/kernel/irq_64.c:77 invoke_softirq kernel/softirq.c:226 [inline] __irq_exit_rcu kernel/softirq.c:420 [inline] irq_exit_rcu+0x134/0x200 kernel/softirq.c:432 sysvec_apic_timer_interrupt+0x4d/0x100 arch/x86/kernel/apic/apic.c:1096 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:628 RIP: 0010:mb_find_extent+0x3e/0xb30 fs/ext4/mballoc.c:1527 Code: df 55 48 89 cd 53 48 89 fb 4c 8d 7b 34 48 81 ec b0 00 00 00 48 8d 44 24 50 89 54 24 04 48 c7 44 24 50 b3 8a b5 41 48 c1 e8 03 <48> 89 44 24 20 4c 01 e0 48 c7 44 24 58 a4 a7 cb 8a 48 c7 44 24 60 RSP: 0018:ffffc900027e7128 EFLAGS: 00010a02 RAX: 1ffff920004fce2f RBX: ffffc900027e7418 RCX: ffffc900027e7290 RDX: 0000000000000460 RSI: 0000000000000281 RDI: ffffc900027e7418 RBP: ffffc900027e7290 R08: 0000000000000281 R09: 0000000000000001 R10: ffffffff820ab2d4 R11: 0000000000000001 R12: dffffc0000000000 R13: 0000000000000281 R14: 0000000000000281 R15: ffffc900027e744c ext4_mb_complex_scan_group+0x323/0x9e0 fs/ext4/mballoc.c:2006 ext4_mb_regular_allocator+0xc1e/0x2180 fs/ext4/mballoc.c:2417 ext4_mb_new_blocks+0x246a/0x51a0 fs/ext4/mballoc.c:4975 ext4_ext_map_blocks+0x20da/0x5fb0 fs/ext4/extents.c:4238 ext4_map_blocks+0x653/0x17d0 fs/ext4/inode.c:637 ext4_alloc_file_blocks.isra.0+0x2fd/0xaf0 fs/ext4/extents.c:4426 ext4_zero_range fs/ext4/extents.c:4537 [inline] ext4_fallocate+0x15c2/0x3fe0 fs/ext4/extents.c:4674 vfs_fallocate+0x48d/0xd70 fs/open.c:309 ioctl_preallocate+0x18e/0x200 fs/ioctl.c:494 file_ioctl fs/ioctl.c:539 [inline] do_vfs_ioctl+0xe16/0x1090 fs/ioctl.c:732 __do_sys_ioctl fs/ioctl.c:751 [inline] __se_sys_ioctl fs/ioctl.c:739 [inline] __x64_sys_ioctl+0x108/0x200 fs/ioctl.c:739 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45e219 Code: 0d b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 db b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f1063029c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045e219 RDX: 0000000020000040 RSI: 0000000040305839 RDI: 0000000000000004 RBP: 000000000119bfc0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000119bf8c R13: 00000000016afb5f R14: 00007f106302a9c0 R15: 000000000119bf8c