syzbot
INFO: rcu detected stall in sys_statfs
Status:
upstream: reported on 2026/07/28 07:22
Reported-by: syzbot+58dd23a42567ad1b734b@syzkaller.appspotmail.com
First crash: 2d15h, last: 2d15h
Sample crash report:
bridge0: received packet on veth1 with own address as source address (addr:aa:aa:aa:aa:aa:18, vlan:0)
bridge0: received packet on veth0 with own address as source address (addr:aa:aa:aa:aa:aa:19, vlan:0)
bridge0: received packet on veth0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P8803/1:b..l
rcu: (detected by 0, t=10502 jiffies, g=45053, q=145 ncpus=1)
task:modprobe state:R running task stack:24360 pid:8803 ppid:35 flags:0x00004002
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5382 [inline]
__schedule+0x15ae/0x4660 kernel/sched/core.c:6701
preempt_schedule_irq+0xbf/0x150 kernel/sched/core.c:7011
irqentry_exit+0x67/0x70 kernel/entry/common.c:438
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:get_current arch/x86/include/asm/current.h:41 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x8/0x60 kernel/kcov.c:215
Code: 00 00 f3 0f 1e fa 53 48 89 fb e8 13 00 00 00 48 8b 3d 0c 0a 05 0d 48 89 de 5b e9 c3 ac 57 00 cc cc cc f3 0f 1e fa 48 8b 04 24 <65> 48 8b 0d 60 43 7c 7e 65 8b 15 61 43 7c 7e 81 e2 00 01 ff 00 74
RSP: 0018:ffffc90003597790 EFLAGS: 00000202
RAX: ffffffff81eae1ab RBX: ffffffff81eae022 RCX: 0000000000000000
RDX: ffff888079b69e00 RSI: 0000000000000001 RDI: 0000000000000000
RBP: 0000000000000001 R08: dffffc0000000000 R09: 1ffffffff223d6a0
R10: dffffc0000000000 R11: fffffbfff223d6a1 R12: dffffc0000000000
R13: 0000000000000060 R14: 000000000001d3f8 R15: ffff888018540000
lookup_page_ext mm/page_ext.c:240 [inline]
page_ext_get+0x1ab/0x2b0 mm/page_ext.c:509
__page_table_check_zero+0x138/0x4b0 mm/page_table_check.c:148
prep_new_page mm/page_alloc.c:1589 [inline]
get_page_from_freelist+0x2181/0x22a0 mm/page_alloc.c:3221
__alloc_pages+0x1f0/0x460 mm/page_alloc.c:4501
alloc_slab_page+0x5d/0x180 mm/slub.c:1881
allocate_slab mm/slub.c:2028 [inline]
new_slab+0x87/0x2d0 mm/slub.c:2081
___slab_alloc+0xc5c/0x12f0 mm/slub.c:3253
__slab_alloc mm/slub.c:3339 [inline]
__slab_alloc_node mm/slub.c:3392 [inline]
slab_alloc_node mm/slub.c:3485 [inline]
slab_alloc mm/slub.c:3503 [inline]
__kmem_cache_alloc_lru mm/slub.c:3510 [inline]
kmem_cache_alloc+0x109/0x2c0 mm/slub.c:3519
getname_flags+0xbb/0x500 fs/namei.c:140
user_path_at_empty+0x2c/0x60 fs/namei.c:2916
user_path_at include/linux/namei.h:57 [inline]
user_statfs+0xa6/0x190 fs/statfs.c:103
__do_sys_statfs fs/statfs.c:195 [inline]
__se_sys_statfs fs/statfs.c:192 [inline]
__x64_sys_statfs+0x121/0x270 fs/statfs.c:192
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7faa83f01487
RSP: 002b:00007fff4198acd8 EFLAGS: 00000246 ORIG_RAX: 0000000000000089
RAX: ffffffffffffffda RBX: 00007faa83dd8305 RCX: 00007faa83f01487
RDX: 0000000000000000 RSI: 00007fff4198ad60 RDI: 00007faa83dd8305
RBP: 00007fff4198ad60 R08: 00007faa840e3af8 R09: 0000000000000000
R10: 00007fff4198ab10 R11: 0000000000000246 R12: 00007fff4198aee8
R13: 00007fff4198af10 R14: 00007faa83ddf4d0 R15: 0000000000000000
</TASK>
rcu: rcu_preempt kthread starved for 10502 jiffies! g45053 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
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:27848 pid:17 ppid:2 flags:0x00004000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5382 [inline]
__schedule+0x15ae/0x4660 kernel/sched/core.c:6701
schedule+0xbd/0x170 kernel/sched/core.c:6775
schedule_timeout+0x188/0x2d0 kernel/time/timer.c:2168
rcu_gp_fqs_loop+0x30d/0x1590 kernel/rcu/tree.c:1667
rcu_gp_kthread+0x9d/0x3b0 kernel/rcu/tree.c:1866
kthread+0x2fa/0x390 kernel/kthread.c:388
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
</TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 PID: 8805 Comm: syz.5.751 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
RIP: 0010:check_kcov_mode kernel/kcov.c:182 [inline]
RIP: 0010:write_comp_data kernel/kcov.c:245 [inline]
RIP: 0010:__sanitizer_cov_trace_cmp8+0x2e/0x80 kernel/kcov.c:293
Code: 48 8b 04 24 65 48 8b 0d 50 41 7c 7e 65 8b 15 51 41 7c 7e 81 e2 00 01 ff 00 74 11 81 fa 00 01 00 00 75 57 83 b9 1c 16 00 00 00 <74> 4e 8b 91 f8 15 00 00 83 fa 03 75 43 48 8b 91 00 16 00 00 44 8b
RSP: 0018:ffffc90000007470 EFLAGS: 00000246
RAX: ffffffff813ba5b2 RBX: ffffffff81000000 RCX: ffff888079b68000
RDX: 0000000000000100 RSI: ffffffff8ac00000 RDI: ffffffff8914bc04
RBP: ffffc90000007500 R08: ffffc90000007610 R09: 000000000000000e
R10: 0000000000000004 R11: 0000000000000100 R12: ffffc900036174a0
R13: ffffc90000007548 R14: ffffffff8914bc04 R15: 0000000000000001
FS: 00007f2d45ffb6c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000e8a030 CR3: 000000004f7c8000 CR4: 00000000003506f0
Call Trace:
<IRQ>
unwind_next_frame+0x1e2/0x2990 arch/x86/kernel/unwind_orc.c:-1
arch_stack_walk+0x144/0x190 arch/x86/kernel/stacktrace.c:25
stack_trace_save+0xaa/0x100 kernel/stacktrace.c:122
kasan_save_stack mm/kasan/common.c:46 [inline]
kasan_set_track+0x4e/0x70 mm/kasan/common.c:53
kasan_save_free_info+0x28/0x40 mm/kasan/generic.c:522
____kasan_slab_free+0x126/0x1f0 mm/kasan/common.c:237
kasan_slab_free include/linux/kasan.h:164 [inline]
slab_free_hook mm/slub.c:1811 [inline]
slab_free_freelist_hook+0x130/0x1a0 mm/slub.c:1837
slab_free mm/slub.c:3830 [inline]
kmem_cache_free+0xf8/0x290 mm/slub.c:3852
kfree_skb include/linux/skbuff.h:1264 [inline]
ip6_mc_input+0xa17/0xc10 net/ipv6/ip6_input.c:589
NF_HOOK+0x32d/0x3b0 include/linux/netfilter.h:304
__netif_receive_skb_one_core net/core/dev.c:5646 [inline]
__netif_receive_skb+0xcc/0x290 net/core/dev.c:5760
process_backlog+0x380/0x710 net/core/dev.c:6088
__napi_poll+0xbb/0x460 net/core/dev.c:6650
napi_poll net/core/dev.c:6717 [inline]
net_rx_action+0x65f/0xcc0 net/core/dev.c:6853
handle_softirqs+0x27d/0x820 kernel/softirq.c:578
do_softirq+0xfa/0x1a0 kernel/softirq.c:479
</IRQ>
<TASK>
__local_bh_enable_ip+0x184/0x1c0 kernel/softirq.c:406
spin_unlock_bh include/linux/spinlock.h:396 [inline]
__skb_recv_udp+0x875/0x950 net/ipv4/udp.c:1738
udpv6_recvmsg+0x31c/0x15f0 net/ipv6/udp.c:355
inet6_recvmsg+0x134/0x650 net/ipv6/af_inet6.c:676
sock_recvmsg_nosec+0x82/0xd0 net/socket.c:1047
____sys_recvmsg+0x4d7/0x5d0 net/socket.c:2812
___sys_recvmsg+0x214/0x590 net/socket.c:2856
do_recvmmsg+0x377/0x810 net/socket.c:2950
__sys_recvmmsg net/socket.c:3029 [inline]
__do_sys_recvmmsg net/socket.c:3052 [inline]
__se_sys_recvmmsg net/socket.c:3045 [inline]
__x64_sys_recvmmsg+0x199/0x250 net/socket.c:3045
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f2d4519de99
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 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 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f2d45ffb028 EFLAGS: 00000246 ORIG_RAX: 000000000000012b
RAX: ffffffffffffffda RBX: 00007f2d45425fa0 RCX: 00007f2d4519de99
RDX: 0000000004000071 RSI: 0000200000002e80 RDI: 0000000000000004
RBP: 00007f2d45233eaf R08: 0000000000000000 R09: 0000000000000000
R10: 000000000000830b R11: 0000000000000246 R12: 0000000000000000
R13: 00007f2d45426038 R14: 00007f2d45425fa0 R15: 00007ffed52a09d8
</TASK>
net_ratelimit: 4181 callbacks suppressed
bridge0: received packet on veth1 with own address as source address (addr:aa:aa:aa:aa:aa:18, vlan:0)
bridge0: received packet on veth0 with own address as source address (addr:aa:aa:aa:aa:aa:19, vlan:0)
bridge0: received packet on veth0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth1 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth1 with own address as source address (addr:aa:aa:aa:aa:aa:18, vlan:0)
bridge0: received packet on veth0 with own address as source address (addr:aa:aa:aa:aa:aa:19, vlan:0)
bridge0: received packet on veth0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth1 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth1 with own address as source address (addr:aa:aa:aa:aa:aa:18, vlan:0)
bridge0: received packet on veth0 with own address as source address (addr:aa:aa:aa:aa:aa:19, vlan:0)
net_ratelimit: 5495 callbacks suppressed
bridge0: received packet on veth0 with own address as source address (addr:aa:aa:aa:aa:aa:19, vlan:0)
bridge0: received packet on veth0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth1 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth1 with own address as source address (addr:aa:aa:aa:aa:aa:18, vlan:0)
bridge0: received packet on veth0 with own address as source address (addr:aa:aa:aa:aa:aa:19, vlan:0)
bridge0: received packet on veth0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth1 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth1 with own address as source address (addr:aa:aa:aa:aa:aa:18, vlan:0)
bridge0: received packet on veth0 with own address as source address (addr:aa:aa:aa:aa:aa:19, vlan:0)
bridge0: received packet on veth0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
* Struck through repros no longer work on HEAD.