rcu: INFO: rcu_preempt self-detected stall on CPU rcu: 0-...!: (10495 ticks this GP) idle=072/1/0x4000000000000002 softirq=24713/24713 fqs=14 (t=10500 jiffies g=34277 q=328) rcu: rcu_preempt kthread starved for 10471 jiffies! g34277 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1 rcu: RCU grace-period kthread stack dump: rcu_preempt R running task 29112 10 2 0x80004000 Call Trace: schedule+0xd0/0x2a0 kernel/sched/core.c:4152 schedule_timeout+0x36b/0x860 kernel/time/timer.c:1898 rcu_gp_fqs_loop kernel/rcu/tree.c:1680 [inline] rcu_gp_kthread+0xc7a/0x1a10 kernel/rcu/tree.c:1848 kthread+0x357/0x430 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 NMI backtrace for cpu 0 CPU: 0 PID: 15808 Comm: syz-executor.1 Not tainted 5.6.0-rc3-next-20200228-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+0x188/0x20d lib/dump_stack.c:118 nmi_cpu_backtrace.cold+0x70/0xb1 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x231/0x27e lib/nmi_backtrace.c:62 trigger_single_cpu_backtrace include/linux/nmi.h:165 [inline] rcu_dump_cpu_stacks+0x19e/0x1e8 kernel/rcu/tree_stall.h:254 print_cpu_stall kernel/rcu/tree_stall.h:475 [inline] check_cpu_stall kernel/rcu/tree_stall.h:549 [inline] rcu_pending kernel/rcu/tree.c:3237 [inline] rcu_sched_clock_irq.cold+0x560/0xcfa kernel/rcu/tree.c:2308 update_process_times+0x25/0x60 kernel/time/timer.c:1727 tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:171 tick_sched_timer+0x4e/0x140 kernel/time/tick-sched.c:1314 __run_hrtimer kernel/time/hrtimer.c:1517 [inline] __hrtimer_run_queues+0x32c/0xdd0 kernel/time/hrtimer.c:1579 hrtimer_interrupt+0x312/0x770 kernel/time/hrtimer.c:1641 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1119 [inline] smp_apic_timer_interrupt+0x15b/0x600 arch/x86/kernel/apic/apic.c:1144 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829 RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:752 [inline] RIP: 0010:lock_acquire+0x209/0x420 kernel/locking/lockdep.c:4723 Code: 9c 08 00 00 00 00 00 00 48 c1 e8 03 80 3c 10 00 0f 85 de 01 00 00 48 83 3d 8b c4 3a 08 00 0f 84 5a 01 00 00 48 8b 3c 24 57 9d <0f> 1f 44 00 00 48 83 c4 18 5b 5d 41 5c 41 5d 41 5e 41 5f c3 65 8b RSP: 0018:ffffc90001c3f120 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff13 RAX: 1ffffffff1327907 RBX: ffff888093a10300 RCX: 1ffff92000387e0d RDX: dffffc0000000000 RSI: 0000000000000000 RDI: 0000000000000286 RBP: ffffffff89812758 R08: 0000000000000001 R09: fffffbfff1852709 R10: ffff888093a10bf0 R11: ffffffff8c293847 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151 spin_lock include/linux/spinlock.h:338 [inline] find_inode_nowait+0x69/0x190 fs/inode.c:1441 ext4_update_other_inodes_time fs/ext4/inode.c:4909 [inline] ext4_do_update_inode fs/ext4/inode.c:5035 [inline] ext4_mark_iloc_dirty+0x21e8/0x2d70 fs/ext4/inode.c:5590 ext4_mark_inode_dirty+0x225/0x900 fs/ext4/inode.c:5783 ext4_dirty_inode+0xe7/0x120 fs/ext4/inode.c:5814 __mark_inode_dirty+0x65e/0x1350 fs/fs-writeback.c:2258 mark_inode_dirty include/linux/fs.h:2183 [inline] generic_write_end+0x2f4/0x3d0 fs/buffer.c:2236 ext4_da_write_end+0x217/0xbd0 fs/ext4/inode.c:3092 generic_perform_write+0x2c0/0x4e0 mm/filemap.c:3304 ext4_buffered_write_iter+0x1f7/0x450 fs/ext4/file.c:270 ext4_file_write_iter+0x1ec/0x13f0 fs/ext4/file.c:642 call_write_iter include/linux/fs.h:1901 [inline] do_iter_readv_writev+0x59c/0x840 fs/read_write.c:693 do_iter_write fs/read_write.c:998 [inline] do_iter_write+0x185/0x600 fs/read_write.c:979 vfs_iter_write+0x70/0xa0 fs/read_write.c:1039 iter_file_splice_write+0x684/0xb00 fs/splice.c:760 do_splice_from fs/splice.c:863 [inline] direct_splice_actor+0x115/0x160 fs/splice.c:1037 splice_direct_to_actor+0x38c/0x980 fs/splice.c:992 do_splice_direct+0x1a8/0x270 fs/splice.c:1080 do_sendfile+0x549/0xc40 fs/read_write.c:1520 __do_sys_sendfile64 fs/read_write.c:1575 [inline] __se_sys_sendfile64 fs/read_write.c:1567 [inline] __x64_sys_sendfile64+0x149/0x210 fs/read_write.c:1567 do_syscall_64+0xf6/0x790 arch/x86/entry/common.c:295 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45c4a9 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:00007f664cc4fc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000028 RAX: ffffffffffffffda RBX: 00007f664cc506d4 RCX: 000000000045c4a9 RDX: 00000000200001c0 RSI: 0000000000000003 RDI: 0000000000000003 RBP: 000000000076bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 00008080fffffffe R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000000008d1 R14: 00000000004cb3b0 R15: 000000000076bf2c