rcu: INFO: rcu_preempt self-detected stall on CPU rcu: 0-....: (1 GPs behind) idle=a26/1/0x4000000000000002 softirq=11533/11539 fqs=2741 (t=10500 jiffies g=6425 q=475) rcu: rcu_preempt kthread starved for 5002 jiffies! g6425 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1 rcu: RCU grace-period kthread stack dump: rcu_preempt R running task 29032 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 0 CPU: 0 PID: 8190 Comm: syz-executor.1 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:check_kcov_mode kernel/kcov.c:79 [inline] RIP: 0010:__sanitizer_cov_trace_pc+0x22/0x50 kernel/kcov.c:102 Code: 64 02 3b 00 5b 5d c3 cc 48 8b 04 24 65 48 8b 0c 25 c0 1d 02 00 65 8b 15 b8 81 8b 7e f7 c2 00 01 1f 00 75 2c 8b 91 80 13 00 00 <83> fa 02 75 21 48 8b 91 88 13 00 00 48 8b 32 48 8d 7e 01 8b 89 84 RSP: 0018:ffffc900020573f0 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13 RAX: ffffffff81487326 RBX: ffffea00026bf180 RCX: ffff8880971202c0 RDX: 0000000000000000 RSI: 00000000fffffffc RDI: ffffea00026bf180 RBP: ffffc90002057418 R08: dffffc0000000000 R09: fffffbfff120248a R10: fffffbfff120248a R11: 0000000000000000 R12: ffff888091ed0e20 R13: dffffc0000000000 R14: 00000000fffffffc R15: ffff888098de9628 free_thread_stack+0x168/0x590 kernel/fork.c:280 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_irq+0xc1/0x140 kernel/sched/core.c:4338 retint_kernel+0x1b/0x2b RIP: 0010:on_stack arch/x86/include/asm/stacktrace.h:43 [inline] RIP: 0010:update_stack_state+0x168/0x530 arch/x86/kernel/unwind_frame.c:224 Code: e1 80 e1 07 80 c1 03 38 c1 7c 60 4c 89 e7 e8 ff dd 7c 00 eb 56 0f 1f 00 66 2e 0f 1f 84 00 00 00 00 00 48 8b 45 c0 80 3c 18 00 <74> 08 4c 89 ff e8 fe dd 7c 00 4d 8b 2f 48 8b 85 58 ff ff ff 80 3c RSP: 0018:ffffc90002057670 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13 RAX: 1ffff9200040aefb RBX: dffffc0000000000 RCX: ffffc900020577f8 RDX: ffffc900020578c0 RSI: 1ffff9200040aefc RDI: ffffc900020577d0 RBP: ffffc90002057718 R08: ffffffff81659cc5 R09: ffffc900020577d0 R10: fffff5200040af06 R11: 0000000000000000 R12: ffffc900020577d0 R13: ffffc900020578b0 R14: ffffc900020577e8 R15: ffffc900020577d8 unwind_next_frame+0x3f1/0x7a0 arch/x86/kernel/unwind_frame.c:311 arch_stack_walk+0xb4/0xe0 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0xb6/0x150 kernel/stacktrace.c:123 save_stack mm/kasan/common.c:71 [inline] set_track mm/kasan/common.c:79 [inline] __kasan_kmalloc+0x11c/0x1b0 mm/kasan/common.c:512 kasan_slab_alloc+0xf/0x20 mm/kasan/common.c:520 slab_post_alloc_hook mm/slab.h:584 [inline] slab_alloc mm/slab.c:3320 [inline] kmem_cache_alloc+0x1f5/0x2e0 mm/slab.c:3484 ext4_alloc_inode+0x1f/0x560 fs/ext4/super.c:1073 alloc_inode fs/inode.c:230 [inline] new_inode_pseudo+0x68/0x240 fs/inode.c:919 new_inode+0x28/0x1c0 fs/inode.c:948 __ext4_new_inode+0x43d/0x56a0 fs/ext4/ialloc.c:824 ext4_symlink+0x52a/0xf60 fs/ext4/namei.c:3275 vfs_symlink+0x36f/0x4f0 fs/namei.c:4123 do_symlinkat+0x187/0x3f0 fs/namei.c:4150 __do_sys_symlink fs/namei.c:4169 [inline] __se_sys_symlink fs/namei.c:4167 [inline] __x64_sys_symlink+0x60/0x70 fs/namei.c:4167 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45a3a7 Code: 0f 1f 00 b8 5c 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 6d b9 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 b8 58 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 4d b9 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007ffdd157d928 EFLAGS: 00000206 ORIG_RAX: 0000000000000058 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000045a3a7 RDX: 00007ffdd157d9c7 RSI: 00000000004c00d3 RDI: 00007ffdd157d9b0 RBP: 0000000000000000 R08: 0000000000000220 R09: 0000000000000017 R10: 0000000000000075 R11: 0000000000000206 R12: 0000000000000001 R13: 00007ffdd157d960 R14: 0000000000000000 R15: 00007ffdd157d970