============================= WARNING: suspicious RCU usage 4.14.105+ #29 Not tainted ----------------------------- net/ipv6/ip6_fib.c:1590 suspicious rcu_dereference_protected() usage! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 6 locks held by syz-executor.4/11298: #0: (&mm->mmap_sem){++++}, at: [] __do_page_fault+0x271/0xb80 arch/x86/mm/fault.c:1354 #1: (rcu_read_lock){....}, at: [] count_memcg_event_mm include/linux/memcontrol.h:651 [inline] #1: (rcu_read_lock){....}, at: [] handle_mm_fault+0xdd/0x6c9 mm/memory.c:4124 #2: (((&net->ipv6.ip6_fib_timer))){+.-.}, at: [] lockdep_copy_map include/linux/lockdep.h:174 [inline] #2: (((&net->ipv6.ip6_fib_timer))){+.-.}, at: [] call_timer_fn+0xc6/0x680 kernel/time/timer.c:1269 #3: (&(&net->ipv6.fib6_gc_lock)->rlock){+.-.}, at: [] spin_lock_bh include/linux/spinlock.h:322 [inline] #3: (&(&net->ipv6.fib6_gc_lock)->rlock){+.-.}, at: [] fib6_run_gc+0x93/0x2a0 net/ipv6/ip6_fib.c:1938 #4: (rcu_read_lock){....}, at: [] __fib6_clean_all+0x0/0x230 net/ipv6/ip6_fib.c:1823 #5: (&tb->tb6_lock){++--}, at: [] __fib6_clean_all+0xde/0x230 net/ipv6/ip6_fib.c:1837 stack backtrace: CPU: 0 PID: 11298 Comm: syz-executor.4 Not tainted 4.14.105+ #29 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0xb9/0x10e lib/dump_stack.c:53 fib6_del+0x8c2/0xbe0 net/ipv6/ip6_fib.c:1590 fib6_clean_node+0x270/0x440 net/ipv6/ip6_fib.c:1777 fib6_walk_continue+0x3a5/0x5f0 net/ipv6/ip6_fib.c:1703 fib6_walk+0x8d/0xe0 net/ipv6/ip6_fib.c:1748 fib6_clean_tree+0xd4/0x110 net/ipv6/ip6_fib.c:1822 __fib6_clean_all+0xf5/0x230 net/ipv6/ip6_fib.c:1838 fib6_clean_all net/ipv6/ip6_fib.c:1849 [inline] fib6_run_gc+0x104/0x2a0 net/ipv6/ip6_fib.c:1947 call_timer_fn+0x14a/0x680 kernel/time/timer.c:1279 expire_timers+0x216/0x4b0 kernel/time/timer.c:1318 __run_timers kernel/time/timer.c:1634 [inline] run_timer_softirq+0x1eb/0x5d0 kernel/time/timer.c:1647 __do_softirq+0x234/0x9ca kernel/softirq.c:288 invoke_softirq kernel/softirq.c:368 [inline] irq_exit+0x114/0x150 kernel/softirq.c:409 exiting_irq arch/x86/include/asm/apic.h:648 [inline] smp_apic_timer_interrupt+0x185/0x620 arch/x86/kernel/apic/apic.c:1064 apic_timer_interrupt+0x84/0x90 arch/x86/entry/entry_64.S:787 RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:778 [inline] RIP: 0010:lock_is_held_type+0xfb/0x150 kernel/locking/lockdep.c:4031 RSP: 0000:ffff8881d0f6fe10 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff10 RAX: 0000000000000007 RBX: 0000000000000246 RCX: 1ffffffff1682390 RDX: 0000000000000000 RSI: 00000000ffffffff RDI: 0000000000000246 RBP: ffff8881cbebaf00 R08: 0000000000000000 R09: 0000000000020025 R10: ffff8881cbebb758 R11: 0000000000000001 R12: 0000000000000000 R13: 00000000004db460 R14: ffff8881c895e420 R15: ffff88819cfbde00 lock_is_held include/linux/lockdep.h:437 [inline] task_css include/linux/cgroup.h:476 [inline] mem_cgroup_from_task+0x95/0x120 mm/memcontrol.c:706 count_memcg_event_mm include/linux/memcontrol.h:655 [inline] handle_mm_fault+0x162/0x6c9 mm/memory.c:4124 __do_page_fault+0x466/0xb80 arch/x86/mm/fault.c:1425 page_fault+0x42/0x50 arch/x86/entry/entry_64.S:1104 RIP: ab685b1f:0x7f60d0e7a9c0 RSP: 73bf08:000000000073bf00 EFLAGS: 0073bf0c EXT4-fs warning (device sda1): ext4_group_add:1607: No reserved GDT blocks, can't resize EXT4-fs warning (device sda1): ext4_group_add:1607: No reserved GDT blocks, can't resize EXT4-fs warning (device sda1): ext4_group_add:1607: No reserved GDT blocks, can't resize EXT4-fs warning (device sda1): ext4_group_add:1607: No reserved GDT blocks, can't resize EXT4-fs warning (device sda1): ext4_group_add:1607: No reserved GDT blocks, can't resize