rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: (detected by 0, t=10502 jiffies, g=62365, q=16) rcu: All QSes seen, last rcu_preempt kthread activity 10501 (4295003350-4294992849), jiffies_till_next_fqs=1, root ->qsmask 0x0 syz-executor.2 R running task 26312 21578 7283 0x00004000 Call Trace: sched_show_task kernel/sched/core.c:5961 [inline] sched_show_task.cold+0x2e2/0x343 kernel/sched/core.c:5936 print_other_cpu_stall kernel/rcu/tree_stall.h:430 [inline] check_cpu_stall kernel/rcu/tree_stall.h:558 [inline] rcu_pending kernel/rcu/tree.c:3225 [inline] rcu_sched_clock_irq.cold+0xb9b/0xcfa kernel/rcu/tree.c:2296 update_process_times+0x25/0x60 kernel/time/timer.c:1727 tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:176 tick_sched_timer+0x4e/0x140 kernel/time/tick-sched.c:1320 __run_hrtimer kernel/time/hrtimer.c:1520 [inline] __hrtimer_run_queues+0x5ca/0xed0 kernel/time/hrtimer.c:1584 hrtimer_interrupt+0x312/0x770 kernel/time/hrtimer.c:1646 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1113 [inline] smp_apic_timer_interrupt+0x15b/0x600 arch/x86/kernel/apic/apic.c:1138 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829 RIP: 0010:write_comp_data+0x1e/0x70 kernel/kcov.c:208 Code: 48 89 11 c3 0f 1f 84 00 00 00 00 00 65 4c 8b 04 25 00 1f 02 00 65 8b 05 68 ea 8e 7e a9 00 01 1f 00 75 51 41 8b 80 d8 13 00 00 <83> f8 03 75 45 49 8b 80 e0 13 00 00 45 8b 80 dc 13 00 00 4c 8b 08 RSP: 0018:ffffc900018574c0 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13 RAX: 0000000000000002 RBX: 0000000000000316 RCX: ffffffff8395074d RDX: 000000000000002e RSI: 0000000000000000 RDI: 0000000000000007 RBP: 0000000000000011 R08: ffff88804be6a500 R09: ffffed1008da1aa0 R10: ffff888046d0d4ff R11: ffffed1008da1a9f R12: 00000000ffffffd0 R13: ffffea0000876540 R14: 0000000000000344 R15: 000000000000002e iov_iter_copy_from_user_atomic+0x2ad/0xc00 lib/iov_iter.c:999 generic_perform_write+0x277/0x4e0 mm/filemap.c:3310 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:1907 [inline] do_iter_readv_writev+0x5a8/0x850 fs/read_write.c:694 do_iter_write fs/read_write.c:999 [inline] do_iter_write+0x18b/0x600 fs/read_write.c:980 vfs_iter_write+0x70/0xa0 fs/read_write.c:1040 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+0x1b4/0x280 fs/splice.c:1080 do_sendfile+0x555/0xc50 fs/read_write.c:1521 __do_sys_sendfile64 fs/read_write.c:1576 [inline] __se_sys_sendfile64 fs/read_write.c:1568 [inline] __x64_sys_sendfile64+0x149/0x210 fs/read_write.c:1568 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295 entry_SYSCALL_64_after_hwframe+0x49/0xb3 RIP: 0033:0x45c889 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:00007f5f21538c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000028 RAX: ffffffffffffffda RBX: 00007f5f215396d4 RCX: 000000000045c889 RDX: 00000000200001c0 RSI: 0000000000000006 RDI: 0000000000000006 RBP: 000000000076c0e0 R08: 0000000000000000 R09: 0000000000000000 R10: 00008080fffffffe R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000000008d6 R14: 00000000004cb7ee R15: 000000000076c0ec rcu: rcu_preempt kthread starved for 10554 jiffies! g62365 f0x2 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1 rcu: RCU grace-period kthread stack dump: rcu_preempt R running task 28848 10 2 0x80004000 Call Trace: schedule+0xd0/0x2a0 kernel/sched/core.c:4163 schedule_timeout+0x35c/0x850 kernel/time/timer.c:1898 rcu_gp_fqs_loop kernel/rcu/tree.c:1674 [inline] rcu_gp_kthread+0x9bf/0x1960 kernel/rcu/tree.c:1836 kthread+0x388/0x470 kernel/kthread.c:268 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352