syzbot

rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	0-....: (10499 ticks this GP) idle=50a/1/0x4000000000000002 softirq=11941/11941 fqs=2755 
	(t=10501 jiffies g=6377 q=182)
rcu: rcu_preempt kthread starved for 4992 jiffies! g6377 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1
rcu: RCU grace-period kthread stack dump:
rcu_preempt     R  running task    28984    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: 8353 Comm: syz-executor.0 Not tainted 5.5.0-rc5-syzkaller #0
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+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:1517 [inline]
 __hrtimer_run_queues+0x403/0x840 kernel/time/hrtimer.c:1579
 hrtimer_interrupt+0x38c/0xda0 kernel/time/hrtimer.c:1641
 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
 </IRQ>
RIP: 0010:__memcg_kmem_uncharge+0x12f/0x1a0 mm/memcontrol.c:2924
Code: 5f 7c 48 89 d8 48 c1 e8 03 42 8a 04 28 84 c0 75 3b f6 03 01 75 10 49 83 c7 10 4c 89 ff 48 8b 75 d0 e8 f5 90 00 00 48 83 c4 08 <5b> 41 5c 41 5d 41 5e 41 5f 5d c3 44 89 e1 80 e1 07 80 c1 03 38 c1
RSP: 0018:ffffc900026778a0 EFLAGS: 00000296 ORIG_RAX: ffffffffffffff13
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffea00025d2340
RBP: ffffc900026778c8 R08: dffffc0000000000 R09: fffffbfff124248a
R10: fffffbfff124248a R11: 0000000000000000 R12: ffffea00025d2340
R13: 1ffffd40004ba46f R14: ffffea00025d2378 R15: 0000000000000000
 memcg_kmem_uncharge include/linux/memcontrol.h:1402 [inline]
 free_thread_stack+0x12e/0x590 kernel/fork.c:284
 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:arch_local_irq_restore arch/x86/include/asm/paravirt.h:752 [inline]
RIP: 0010:kfree+0x1a3/0x200 mm/slab.c:3758
Code: 48 83 3d 07 04 78 07 00 74 68 4c 89 f7 57 9d 0f 1f 44 00 00 eb 19 e8 3c d3 c9 ff 48 83 3d ec 03 78 07 00 74 51 4c 89 f7 57 9d <0f> 1f 44 00 00 5b 41 5c 41 5e 41 5f 5d c3 48 ff c9 48 89 c8 e9 c8
RSP: 0018:ffffc90002677b20 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff13
RAX: ffff888094da0e14 RBX: ffff8880aa4001c0 RCX: ffffffff815c1e17
RDX: 0000000000000000 RSI: 0000000000000008 RDI: 0000000000000286
RBP: ffffc90002677b40 R08: ffff888094da0dd8 R09: fffffbfff140cf2e
R10: fffffbfff140cf2e R11: 0000000000000000 R12: ffff8880a6929f40
R13: 0000000000000000 R14: 0000000000000286 R15: ffffffff835335a1
 security_inode_init_security+0x281/0x310 security/security.c:999
 ext4_init_security+0x34/0x40 fs/ext4/xattr_security.c:57
 __ext4_new_inode+0x44f5/0x56f0 fs/ext4/ialloc.c:1155
 ext4_symlink+0x52a/0xf60 fs/ext4/namei.c:3281
 vfs_symlink+0x36f/0x4f0 fs/namei.c:4131
 do_symlinkat+0x187/0x3f0 fs/namei.c:4158
 __do_sys_symlink fs/namei.c:4177 [inline]
 __se_sys_symlink fs/namei.c:4175 [inline]
 __x64_sys_symlink+0x60/0x70 fs/namei.c:4175
 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45ac77
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:00007ffdfb1bbdc8 EFLAGS: 00000202 ORIG_RAX: 0000000000000058
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000045ac77
RDX: 00007ffdfb1bbe67 RSI: 00000000004c0a21 RDI: 00007ffdfb1bbe50
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000017
R10: 0000000000000075 R11: 0000000000000202 R12: 0000000000000001
R13: 00007ffdfb1bbe00 R14: 0000000000000000 R15: 00007ffdfb1bbe10