rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 1-...!: (0 ticks this GP) idle=c12/1/0x4000000000000000 softirq=38022/38023 fqs=0 (detected by 0, t=10502 jiffies, g=64065, q=10) Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 7021 Comm: syz-executor.2 Not tainted 5.8.0-rc3-next-20200703-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:debug_spin_unlock kernel/locking/spinlock_debug.c:100 [inline] RIP: 0010:do_raw_spin_unlock+0xe3/0x230 kernel/locking/spinlock_debug.c:138 Code: 65 08 48 b8 00 00 00 00 00 fc ff df 4c 89 e2 48 c1 ea 03 0f b6 04 02 84 c0 74 08 3c 03 0f 8e fc 00 00 00 65 8b 05 bd 65 a6 7e <39> 45 08 0f 85 b5 00 00 00 48 b8 00 00 00 00 00 fc ff df 4c 89 ea RSP: 0018:ffffc90000da8db0 EFLAGS: 00000046 RAX: 0000000000000001 RBX: 0000000000000082 RCX: ffffffff815b2d10 RDX: 1ffff11015ce4ee9 RSI: 0000000000000004 RDI: ffff8880ae727740 RBP: ffff8880ae727740 R08: 0000000000000000 R09: ffff8880ae727743 R10: ffffed1015ce4ee8 R11: 0000000000000000 R12: ffff8880ae727748 R13: ffff8880ae727750 R14: ffff8880a859c340 R15: dffffc0000000000 FS: 0000000001962940(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000b90004 CR3: 000000005955f000 CR4: 00000000001526e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:159 [inline] _raw_spin_unlock_irqrestore+0x1e/0xe0 kernel/locking/spinlock.c:191 __run_hrtimer kernel/time/hrtimer.c:1516 [inline] __hrtimer_run_queues+0x5d1/0xfc0 kernel/time/hrtimer.c:1584 hrtimer_interrupt+0x32a/0x930 kernel/time/hrtimer.c:1646 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1080 [inline] __sysvec_apic_timer_interrupt+0x142/0x5e0 arch/x86/kernel/apic/apic.c:1097 asm_call_on_stack+0xf/0x20 arch/x86/entry/entry_64.S:706 __run_on_irqstack arch/x86/include/asm/irq_stack.h:22 [inline] run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:48 [inline] sysvec_apic_timer_interrupt+0xe0/0x120 arch/x86/kernel/apic/apic.c:1091 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:596 RIP: 0010:mark_buffer_dirty_inode+0x79/0x3c0 fs/buffer.c:574 Code: ea 03 80 3c 02 00 0f 85 b5 02 00 00 48 b8 00 00 00 00 00 fc ff df 4c 8b 63 10 49 8d 7c 24 18 48 89 fa 48 c1 ea 03 80 3c 02 00 <0f> 85 87 02 00 00 48 89 df 4d 8b 6c 24 18 e8 44 f9 ff ff 48 8d bd RSP: 0018:ffffc90004a17900 EFLAGS: 00000246 RAX: dffffc0000000000 RBX: ffff8880493a12b8 RCX: ffffffff821b8dd4 RDX: 1ffffd40004d1c2b RSI: ffffffff81cde4f9 RDI: ffffea000268e158 RBP: ffff8880491fcb88 R08: 0000000000000000 R09: ffff8880493a12bf R10: 000000000fffffff R11: 0000000000000000 R12: ffffea000268e140 R13: 00000000000016b0 R14: ffff888088d2c000 R15: 0000000000000008 fat_free_clusters+0x34b/0x990 fs/fat/fatent.c:595 fat_free.isra.0+0x5e2/0x940 fs/fat/file.c:375 fat_truncate_blocks+0x122/0x199 fs/fat/file.c:393 fat_free_eofblocks fs/fat/inode.c:632 [inline] fat_evict_inode+0x1cc/0x260 fs/fat/inode.c:657 evict+0x2ed/0x750 fs/inode.c:576 dispose_list+0x117/0x1d0 fs/inode.c:611 evict_inodes+0x350/0x440 fs/inode.c:661 generic_shutdown_super+0xab/0x370 fs/super.c:463 kill_block_super+0x97/0xf0 fs/super.c:1455 deactivate_locked_super+0x110/0x1f0 fs/super.c:344 deactivate_super+0xad/0xd0 fs/super.c:375 cleanup_mnt+0x399/0x500 fs/namespace.c:1139 task_work_run+0xdd/0x190 kernel/task_work.c:135 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_usermode_loop arch/x86/entry/common.c:222 [inline] __prepare_exit_to_usermode+0x1e9/0x1f0 arch/x86/entry/common.c:252 do_syscall_64+0x6c/0xe0 arch/x86/entry/common.c:376 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45f557 Code: Bad RIP value. RSP: 002b:00007fff6fb563c8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 000000000045f557 RDX: 00000000004031d8 RSI: 0000000000000002 RDI: 00007fff6fb56470 RBP: 0000000000000489 R08: 0000000000000000 R09: 000000000000000b R10: 0000000000000005 R11: 0000000000000246 R12: 00007fff6fb57500 R13: 0000000001963940 R14: 0000000000000000 R15: 00007fff6fb57500 rcu: rcu_preempt kthread starved for 10502 jiffies! g64065 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: rcu_preempt R running task 29352 10 2 0x00004000 Call Trace: context_switch kernel/sched/core.c:3445 [inline] __schedule+0x8b4/0x1e80 kernel/sched/core.c:4169 schedule+0xd0/0x2a0 kernel/sched/core.c:4244 schedule_timeout+0x148/0x250 kernel/time/timer.c:1897 rcu_gp_fqs_loop kernel/rcu/tree.c:1870 [inline] rcu_gp_kthread+0xae5/0x1b50 kernel/rcu/tree.c:2040 kthread+0x3b5/0x4a0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294