syzbot

RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffffffffffff R11: 0000000000000246 R12: 0000000000000014
R13: 0000000000000459 R14: 00000000006f98f8 R15: 0000000000000003
INFO: rcu_sched self-detected stall on CPU
	1-...!: (124998 ticks this GP) idle=cfa/1/4611686018427387906 softirq=61323/61323 fqs=6 
	 (t=125000 jiffies g=28045 c=28044 q=59)
rcu_sched kthread starved for 124976 jiffies! g28045 c28044 f0x0 RCU_GP_WAIT_FQS(3) ->state=0x0 ->cpu=0
RCU grace-period kthread stack dump:
rcu_sched       R  running task    23768     9      2 0x80000000
Call Trace:
 context_switch kernel/sched/core.c:2848 [inline]
 __schedule+0x801/0x1e30 kernel/sched/core.c:3490
 schedule+0xef/0x430 kernel/sched/core.c:3549
 schedule_timeout+0x138/0x240 kernel/time/timer.c:1801
 rcu_gp_kthread+0x6b5/0x1940 kernel/rcu/tree.c:2231
 kthread+0x345/0x410 kernel/kthread.c:238
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:411
NMI backtrace for cpu 1
CPU: 1 PID: 13448 Comm: syz-executor4 Not tainted 4.16.0+ #4
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1b9/0x294 lib/dump_stack.c:113
 nmi_cpu_backtrace.cold.4+0x19/0xce lib/nmi_backtrace.c:103
 nmi_trigger_cpumask_backtrace+0x151/0x192 lib/nmi_backtrace.c:62
 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 trigger_single_cpu_backtrace include/linux/nmi.h:156 [inline]
 rcu_dump_cpu_stacks+0x175/0x1c2 kernel/rcu/tree.c:1376
 print_cpu_stall kernel/rcu/tree.c:1525 [inline]
 check_cpu_stall.isra.61.cold.80+0x36c/0x59a kernel/rcu/tree.c:1593
 __rcu_pending kernel/rcu/tree.c:3356 [inline]
 rcu_pending kernel/rcu/tree.c:3401 [inline]
 rcu_check_callbacks+0x21b/0xad0 kernel/rcu/tree.c:2763
 update_process_times+0x2d/0x70 kernel/time/timer.c:1636
 tick_sched_handle+0x9f/0x180 kernel/time/tick-sched.c:173
 tick_sched_timer+0x45/0x130 kernel/time/tick-sched.c:1283
 __run_hrtimer kernel/time/hrtimer.c:1386 [inline]
 __hrtimer_run_queues+0x3e3/0x10a0 kernel/time/hrtimer.c:1448
 hrtimer_interrupt+0x286/0x650 kernel/time/hrtimer.c:1506
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1025 [inline]
 smp_apic_timer_interrupt+0x15d/0x710 arch/x86/kernel/apic/apic.c:1050
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:862
 </IRQ>
RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:783 [inline]
RIP: 0010:kmem_cache_free+0xb3/0x2d0 mm/slab.c:3757
RSP: 0000:ffff880184eeee50 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13
RAX: 0000000000000007 RBX: ffff88017b505200 RCX: 1ffff10035934de0
RDX: 0000000000000000 RSI: ffff8801ac9a6ee0 RDI: 0000000000000282
RBP: ffff880184eeee70 R08: ffff8801ac9a6eb8 R09: 0000000000000006
R10: ffff8801ac9a6680 R11: 0000000000000000 R12: ffff8801d42273c0
R13: 0000000000000282 R14: ffffffff8212f9be R15: ffff8801ac9a6680
 jbd2_free_handle include/linux/jbd2.h:1426 [inline]
 jbd2_journal_stop+0x42e/0x15a0 fs/jbd2/transaction.c:1781
 __ext4_journal_stop+0xde/0x1f0 fs/ext4/ext4_jbd2.c:103
 ext4_da_write_end+0x4e1/0xc30 fs/ext4/inode.c:3181
 generic_perform_write+0x4c9/0x6a0 mm/filemap.c:3151
 __generic_file_write_iter+0x3be/0x5e0 mm/filemap.c:3265
 ext4_file_write_iter+0x6dc/0x12e0 fs/ext4/file.c:266
 call_write_iter include/linux/fs.h:1784 [inline]
 do_iter_readv_writev+0x6a0/0x970 fs/read_write.c:680
 do_iter_write+0x185/0x5f0 fs/read_write.c:959
 vfs_iter_write+0x77/0xb0 fs/read_write.c:972
 iter_file_splice_write+0x8cb/0xff0 fs/splice.c:749
 do_splice_from fs/splice.c:851 [inline]
 direct_splice_actor+0x128/0x190 fs/splice.c:1018
 splice_direct_to_actor+0x310/0x8d0 fs/splice.c:973
 do_splice_direct+0x2cc/0x400 fs/splice.c:1061
 do_sendfile+0x60f/0xe00 fs/read_write.c:1440
 SYSC_sendfile64 fs/read_write.c:1495 [inline]
 SyS_sendfile64+0xdf/0x190 fs/read_write.c:1487
 do_syscall_64+0x29e/0x9d0 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x455319
RSP: 002b:00007f22daf79c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f22daf7a6d4 RCX: 0000000000455319
RDX: 0000000020000040 RSI: 0000000000000017 RDI: 0000000000000017
RBP: 000000000072bf58 R08: 0000000000000000 R09: 0000000000000000
R10: 7527fb3200000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000004c6 R14: 00000000006fa330 R15: 0000000000000001