rcu: INFO: rcu_preempt self-detected stall on CPU rcu: 1-...!: (1 GPs behind) idle=dc2/1/0x4000000000000002 softirq=10557/10568 fqs=35 (t=10501 jiffies g=5981 q=55) rcu: rcu_preempt kthread starved for 10432 jiffies! g5981 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0 rcu: RCU grace-period kthread stack dump: rcu_preempt R running task 29048 10 2 0x80004000 Call Trace: context_switch kernel/sched/core.c:3385 [inline] __schedule+0x9a0/0xcc0 kernel/sched/core.c:4081 schedule+0x181/0x210 kernel/sched/core.c:4155 schedule_timeout+0x14f/0x240 kernel/time/timer.c:1895 rcu_gp_fqs_loop kernel/rcu/tree.c:1661 [inline] rcu_gp_kthread+0xed8/0x1770 kernel/rcu/tree.c:1821 kthread+0x332/0x350 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 NMI backtrace for cpu 1 CPU: 1 PID: 8132 Comm: syz-executor.0 Not tainted 5.4.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1fb/0x318 lib/dump_stack.c:118 nmi_cpu_backtrace+0xaf/0x1a0 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x174/0x290 lib/nmi_backtrace.c:62 arch_trigger_cpumask_backtrace+0x10/0x20 arch/x86/kernel/apic/hw_nmi.c:38 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline] rcu_dump_cpu_stacks+0x15a/0x220 kernel/rcu/tree_stall.h:254 print_cpu_stall kernel/rcu/tree_stall.h:455 [inline] check_cpu_stall kernel/rcu/tree_stall.h:529 [inline] rcu_pending kernel/rcu/tree.c:2827 [inline] rcu_sched_clock_irq+0xe25/0x1ad0 kernel/rcu/tree.c:2271 update_process_times+0x12d/0x180 kernel/time/timer.c:1726 tick_sched_handle kernel/time/tick-sched.c:167 [inline] tick_sched_timer+0x263/0x420 kernel/time/tick-sched.c:1310 __run_hrtimer kernel/time/hrtimer.c:1514 [inline] __hrtimer_run_queues+0x403/0x840 kernel/time/hrtimer.c:1576 hrtimer_interrupt+0x38c/0xda0 kernel/time/hrtimer.c:1638 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1110 [inline] smp_apic_timer_interrupt+0x109/0x280 arch/x86/kernel/apic/apic.c:1135 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829 RIP: 0010:__memcg_kmem_uncharge+0x0/0x2e0 mm/memcontrol.c:2909 Code: 00 eb 1b 83 3d 40 90 8c 07 00 74 12 48 81 c3 08 02 00 00 48 89 df 4c 89 f6 e8 dc 7d ff ff 5b 41 5e 5d c3 0f 1f 80 00 00 00 00 <55> 48 89 e5 41 57 41 56 41 55 41 54 53 50 89 f3 49 89 fc 48 b8 00 RSP: 0018:ffffc900020975f0 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13 RAX: ffffffff81486ea4 RBX: ffffea0002439440 RCX: 0000000000040000 RDX: ffffc900020b9000 RSI: 0000000000000000 RDI: ffffea0002439440 RBP: ffffc90002097630 R08: 000000000003a768 R09: ffffed10141f2a87 R10: ffffed10141f2a87 R11: 0000000000000000 R12: ffff8880987c0e20 R13: dffffc0000000000 R14: 1ffff110130f81c4 R15: ffff8880a0f95428 release_task_stack kernel/fork.c:440 [inline] put_task_stack+0xa3/0x130 kernel/fork.c:451 finish_task_switch+0x3f1/0x550 kernel/sched/core.c:3256 context_switch kernel/sched/core.c:3388 [inline] __schedule+0x9a8/0xcc0 kernel/sched/core.c:4081 preempt_schedule_common kernel/sched/core.c:4236 [inline] preempt_schedule+0xdb/0x120 kernel/sched/core.c:4261 ___preempt_schedule+0x16/0x18 arch/x86/entry/thunk_64.S:50 __raw_write_unlock include/linux/rwlock_api_smp.h:220 [inline] _raw_write_unlock+0x3a/0x40 kernel/locking/spinlock.c:327 ext4_es_insert_delayed_block+0x3e2/0x490 fs/ext4/extents_status.c:1999 ext4_insert_delayed_block fs/ext4/inode.c:1657 [inline] ext4_da_map_blocks fs/ext4/inode.c:1748 [inline] ext4_da_get_block_prep+0x90f/0x1250 fs/ext4/inode.c:1812 ext4_block_write_begin+0x80c/0x13e0 fs/ext4/inode.c:1055 ext4_da_write_begin+0x70e/0xf70 fs/ext4/inode.c:2996 generic_perform_write+0x25d/0x4e0 mm/filemap.c:3309 ext4_buffered_write_iter+0x467/0x5f0 fs/ext4/file.c:252 ext4_file_write_iter+0x546/0x1f50 include/linux/fs.h:796 call_write_iter include/linux/fs.h:1902 [inline] new_sync_write fs/read_write.c:483 [inline] __vfs_write+0x5a1/0x740 fs/read_write.c:496 vfs_write+0x275/0x590 fs/read_write.c:558 ksys_write+0x117/0x220 fs/read_write.c:611 __do_sys_write fs/read_write.c:623 [inline] __se_sys_write fs/read_write.c:620 [inline] __x64_sys_write+0x7b/0x90 fs/read_write.c:620 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45a679 Code: ad b6 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 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007fd4c8aedc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045a679 RDX: 000000007c774aac RSI: 0000000020000040 RDI: 0000000000000003 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007fd4c8aee6d4 R13: 00000000004cba7c R14: 00000000004e5650 R15: 00000000ffffffff