=============================
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: [<ffffffff88eb4671>] __do_page_fault+0x271/0xb80 arch/x86/mm/fault.c:1354
#1: (rcu_read_lock){....}, at: [<ffffffff892d383d>] count_memcg_event_mm include/linux/memcontrol.h:651 [inline]
#1: (rcu_read_lock){....}, at: [<ffffffff892d383d>] handle_mm_fault+0xdd/0x6c9 mm/memory.c:4124
#2: (((&net->ipv6.ip6_fib_timer))){+.-.}, at: [<ffffffff890639c6>] lockdep_copy_map include/linux/lockdep.h:174 [inline]
#2: (((&net->ipv6.ip6_fib_timer))){+.-.}, at: [<ffffffff890639c6>] call_timer_fn+0xc6/0x680 kernel/time/timer.c:1269
#3: (&(&net->ipv6.fib6_gc_lock)->rlock){+.-.}, at: [<ffffffff8a4edc13>] spin_lock_bh include/linux/spinlock.h:322 [inline]
#3: (&(&net->ipv6.fib6_gc_lock)->rlock){+.-.}, at: [<ffffffff8a4edc13>] fib6_run_gc+0x93/0x2a0 net/ipv6/ip6_fib.c:1938
#4: (rcu_read_lock){....}, at: [<ffffffff8a4e51b0>] __fib6_clean_all+0x0/0x230 net/ipv6/ip6_fib.c:1823
#5: (&tb->tb6_lock){++--}, at: [<ffffffff8a4e528e>] __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:
<IRQ>
__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
</IRQ>
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