rcu: INFO: rcu_preempt self-detected stall on CPU rcu: 0-...!: (10507 ticks this GP) idle=96a/1/0x4000000000000000 softirq=158854/158856 fqs=0 (t=10501 jiffies g=297601 q=1) rcu: rcu_preempt kthread starved for 10501 jiffies! g297601 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1 rcu: Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior. rcu: RCU grace-period kthread stack dump: task:rcu_preempt state:R running task stack:29000 pid: 11 ppid: 2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:3774 [inline] __schedule+0x893/0x2130 kernel/sched/core.c:4523 schedule+0xcf/0x270 kernel/sched/core.c:4601 schedule_timeout+0x148/0x250 kernel/time/timer.c:1871 rcu_gp_fqs_loop kernel/rcu/tree.c:1925 [inline] rcu_gp_kthread+0xb4c/0x1c90 kernel/rcu/tree.c:2099 kthread+0x3af/0x4a0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296 NMI backtrace for cpu 0 CPU: 0 PID: 28245 Comm: syz-executor.3 Not tainted 5.10.0-rc2-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+0x107/0x163 lib/dump_stack.c:118 nmi_cpu_backtrace.cold+0x44/0xd7 lib/nmi_backtrace.c:105 nmi_trigger_cpumask_backtrace+0x1b3/0x230 lib/nmi_backtrace.c:62 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline] rcu_dump_cpu_stacks+0x1e3/0x21e kernel/rcu/tree_stall.h:318 print_cpu_stall kernel/rcu/tree_stall.h:551 [inline] check_cpu_stall kernel/rcu/tree_stall.h:625 [inline] rcu_pending kernel/rcu/tree.c:3694 [inline] rcu_sched_clock_irq.cold+0x4db/0xded kernel/rcu/tree.c:2567 update_process_times+0x77/0xd0 kernel/time/timer.c:1709 tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:176 tick_sched_timer+0x1d1/0x2a0 kernel/time/tick-sched.c:1328 __run_hrtimer kernel/time/hrtimer.c:1519 [inline] __hrtimer_run_queues+0x1ce/0xea0 kernel/time/hrtimer.c:1583 hrtimer_interrupt+0x334/0x940 kernel/time/hrtimer.c:1645 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1080 [inline] __sysvec_apic_timer_interrupt+0x146/0x540 arch/x86/kernel/apic/apic.c:1097 run_sysvec_on_irqstack_cond arch/x86/include/asm/irq_stack.h:91 [inline] sysvec_apic_timer_interrupt+0x48/0x100 arch/x86/kernel/apic/apic.c:1091 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:631 RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline] RIP: 0010:_raw_spin_unlock_irqrestore+0x25/0x50 kernel/locking/spinlock.c:191 Code: f8 5d c3 66 90 55 48 89 fd 48 83 c7 18 53 48 89 f3 48 8b 74 24 10 e8 1a 59 6f f8 48 89 ef e8 82 19 70 f8 f6 c7 02 75 1a 53 9d 01 00 00 00 e8 d1 6b 64 f8 65 8b 05 ba 26 1b 77 85 c0 74 0a 5b RSP: 0018:ffffc90000007a10 EFLAGS: 00000a06 RAX: 0000000000ce491c RBX: 0000000000000a06 RCX: ffffffff81559817 RDX: 0000000000000000 RSI: 0000000000000302 RDI: 0000000000000000 RBP: ffffffff8f140be0 R08: 0000000000000001 R09: ffffffff8ebad737 R10: fffffbfff1d75ae6 R11: 0000000000000000 R12: 000000000000000c R13: 000000000000000c R14: dead000000000100 R15: dffffc0000000000 __debug_check_no_obj_freed lib/debugobjects.c:997 [inline] debug_check_no_obj_freed+0x20c/0x420 lib/debugobjects.c:1018 slab_free_hook mm/slub.c:1536 [inline] slab_free_freelist_hook+0x107/0x150 mm/slub.c:1577 slab_free mm/slub.c:3142 [inline] kmem_cache_free+0x82/0x350 mm/slub.c:3158 kfree_skbmem+0xef/0x1b0 net/core/skbuff.c:622 __kfree_skb net/core/skbuff.c:679 [inline] kfree_skb net/core/skbuff.c:696 [inline] kfree_skb+0x140/0x3f0 net/core/skbuff.c:690 kfree_skb_list+0x3f/0x60 net/core/skbuff.c:705 __dev_xmit_skb net/core/dev.c:3809 [inline] __dev_queue_xmit+0x14fa/0x2da0 net/core/dev.c:4108 mrp_queue_xmit net/802/mrp.c:351 [inline] mrp_join_timer+0x8a/0xc0 net/802/mrp.c:595 call_timer_fn+0x1a5/0x6b0 kernel/time/timer.c:1410 expire_timers kernel/time/timer.c:1455 [inline] __run_timers.part.0+0x67c/0xa50 kernel/time/timer.c:1747 __run_timers kernel/time/timer.c:1728 [inline] run_timer_softirq+0xb3/0x1d0 kernel/time/timer.c:1760 __do_softirq+0x2a0/0x9f6 kernel/softirq.c:298 asm_call_irq_on_stack+0xf/0x20 __run_on_irqstack arch/x86/include/asm/irq_stack.h:26 [inline] run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:77 [inline] do_softirq_own_stack+0xaa/0xd0 arch/x86/kernel/irq_64.c:77 invoke_softirq kernel/softirq.c:393 [inline] __irq_exit_rcu kernel/softirq.c:423 [inline] irq_exit_rcu+0x132/0x200 kernel/softirq.c:435 sysvec_apic_timer_interrupt+0x4d/0x100 arch/x86/kernel/apic/apic.c:1091 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:631 RIP: 0010:map_id_up+0x3c/0x2f0 kernel/user_namespace.c:354 Code: 00 00 00 00 00 fc ff df 48 83 ec 70 48 8d 44 24 10 48 89 3c 24 48 c7 44 24 10 b3 8a b5 41 48 c1 e8 03 48 89 44 24 08 48 01 d8 <48> c7 44 24 18 5e 01 c6 8a 48 c7 44 24 20 00 59 6c 81 c7 00 f1 f1 RSP: 0018:ffffc900170af0e0 EFLAGS: 00000286 RAX: fffff52002e15e1e RBX: dffffc0000000000 RCX: ffffc9000f248000 RDX: 0000000000040000 RSI: 0000000000000000 RDI: ffffffff8b1fe940 RBP: ffffffff8b1fe940 R08: 0000000000000001 R09: ffff888068840057 R10: ffffed100d10800a R11: 0000000000000000 R12: 0000000000000000 R13: ffffc900170af320 R14: ffffffff8b1fe940 R15: ffffc900170af320 from_kuid+0x85/0xc0 kernel/user_namespace.c:408 i_uid_read include/linux/fs.h:1559 [inline] ext4_do_update_inode fs/ext4/inode.c:5042 [inline] ext4_mark_iloc_dirty+0x65b/0x36e0 fs/ext4/inode.c:5711 __ext4_mark_inode_dirty+0x21d/0x8a0 fs/ext4/inode.c:5905 ext4_dirty_inode+0xf3/0x130 fs/ext4/inode.c:5941 __mark_inode_dirty+0x888/0x1190 fs/fs-writeback.c:2260 mark_inode_dirty_sync include/linux/fs.h:2172 [inline] dquot_free_space include/linux/quotaops.h:382 [inline] dquot_free_block include/linux/quotaops.h:392 [inline] ext4_free_blocks+0x189c/0x1de0 fs/ext4/mballoc.c:5493 ext4_remove_blocks fs/ext4/extents.c:2498 [inline] ext4_ext_rm_leaf fs/ext4/extents.c:2664 [inline] ext4_ext_remove_space+0x1f9e/0x4260 fs/ext4/extents.c:2912 ext4_ext_truncate+0x1dc/0x240 fs/ext4/extents.c:4373 ext4_truncate+0xe86/0x1420 fs/ext4/inode.c:4253 ext4_setattr+0x133c/0x1ff0 fs/ext4/inode.c:5492 notify_change+0xb60/0x10a0 fs/attr.c:336 do_truncate+0x134/0x1f0 fs/open.c:64 handle_truncate fs/namei.c:2910 [inline] do_open fs/namei.c:3256 [inline] path_openat+0x2054/0x2730 fs/namei.c:3369 do_filp_open+0x17e/0x3c0 fs/namei.c:3396 do_sys_openat2+0x16d/0x420 fs/open.c:1168 do_sys_open fs/open.c:1184 [inline] __do_sys_creat fs/open.c:1258 [inline] __se_sys_creat fs/open.c:1252 [inline] __x64_sys_creat+0xc9/0x120 fs/open.c:1252 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45deb9 Code: 0d b4 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 db b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f1d15439c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000055 RAX: ffffffffffffffda RBX: 0000000000002a00 RCX: 000000000045deb9 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000240 RBP: 000000000118bf58 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118bf2c R13: 000000000169fb7f R14: 00007f1d1543a9c0 R15: 000000000118bf2c