Hello,
syzbot found the following issue on:
HEAD commit: da47cbc25466 Linux 6.6.144
git tree: linux-6.6.y
console output:
https://syzkaller.appspot.com/x/log.txt?x=138e5c32580000
kernel config:
https://syzkaller.appspot.com/x/.config?x=938110aa66424b94
dashboard link:
https://syzkaller.appspot.com/bug?extid=2e5e664c4a8921206a3e
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image:
https://storage.googleapis.com/syzbot-assets/f9357b0848a4/disk-da47cbc2.raw.xz
vmlinux:
https://storage.googleapis.com/syzbot-assets/0d72e4376571/vmlinux-da47cbc2.xz
kernel image:
https://storage.googleapis.com/syzbot-assets/69ce7d2e1989/bzImage-da47cbc2.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by:
syzbot+2e5e66...@syzkaller.appspotmail.com
rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 0-....: (10500 ticks this GP) idle=3ed4/1/0x4000000000000000 softirq=38255/38256 fqs=1158
rcu: hardirqs softirqs csw/system
rcu: number: 1420758 5 0
rcu: cputime: 13805 37144 43 ==> 50980(ms)
rcu: (t=10504 jiffies g=50601 q=2594 ncpus=2)
rcu: rcu_preempt kthread timer wakeup didn't happen for 2809 jiffies! g50601 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: Possible timer handling issue on cpu=1 timer-softirq=32323
rcu: rcu_preempt kthread starved for 2812 jiffies! g50601 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->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:I stack:26856 pid:17 ppid:2 flags:0x00004000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5381 [inline]
__schedule+0x15ae/0x4660 kernel/sched/core.c:6700
schedule+0xbd/0x170 kernel/sched/core.c:6774
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:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 5757 Comm: syz-executor Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:pv_native_safe_halt+0xf/0x10 arch/x86/kernel/paravirt.c:148
Code: 4c 1d 02 c3 cc cc cc cc cc cc cc f3 0f 1e fa 0f 0b 66 2e 0f 1f 84 00 00 00 00 00 f3 0f 1e fa 66 90 0f 00 2d 43 77 3c 00 fb f4 <c3> 66 0f 1f 00 55 41 57 41 56 41 54 53 50 8b 2f eb 2c 89 cb 80 f9
RSP: 0018:ffffc900044ff6f8 EFLAGS: 000002d3
RAX: ffffffff813a9538 RBX: 0000000000000003 RCX: ffff888076631e00
RDX: 0000000000000000 RSI: ffffffff8acacb60 RDI: ffffffff8b1cfa20
RBP: ffffc900044ff7d0 R08: ffffffff911e75c7 R09: 1ffffffff223ceb8
R10: dffffc0000000000 R11: fffffbfff223ceb9 R12: dffffc0000000000
R13: 0000000000000200 R14: 0000000000000003 R15: 1ffff9200089fee4
FS: 000055557e709500(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fff4d6fcfe0 CR3: 000000002eb1a000 CR4: 00000000003506e0
DR0: 0000200000000300 DR1: 0000200000000300 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
<TASK>
arch_safe_halt arch/x86/include/asm/paravirt.h:108 [inline]
kvm_wait+0x23d/0x2a0 arch/x86/kernel/kvm.c:1058
pv_wait arch/x86/include/asm/paravirt.h:598 [inline]
pv_wait_head_or_lock kernel/locking/qspinlock_paravirt.h:470 [inline]
__pv_queued_spin_lock_slowpath+0x613/0x9c0 kernel/locking/qspinlock.c:511
pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:586 [inline]
queued_spin_lock_slowpath arch/x86/include/asm/qspinlock.h:51 [inline]
queued_spin_lock include/asm-generic/qspinlock.h:114 [inline]
do_raw_spin_lock+0x23e/0x2b0 kernel/locking/spinlock_debug.c:115
spin_lock_bh include/linux/spinlock.h:356 [inline]
lock_sock_nested+0x6a/0x100 net/core/sock.c:3547
lock_sock include/net/sock.h:1780 [inline]
tcp_recvmsg+0x1fb/0x830 net/ipv4/tcp.c:2607
inet_recvmsg+0x140/0x1f0 net/ipv4/af_inet.c:882
sock_recvmsg_nosec net/socket.c:1047 [inline]
sock_recvmsg net/socket.c:1069 [inline]
sock_read_iter+0x2db/0x3f0 net/socket.c:1139
call_read_iter include/linux/fs.h:2012 [inline]
new_sync_read fs/read_write.c:389 [inline]
vfs_read+0x486/0x990 fs/read_write.c:470
ksys_read+0x151/0x260 fs/read_write.c:613
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: 0033:0x7fdadb159017
Code: 48 89 fa 4c 89 df e8 a8 56 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff
RSP: 002b:00007ffeaf98c010 EFLAGS: 00000202 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 000055557e709500 RCX: 00007fdadb159017
RDX: 0000000000000004 RSI: 00007ffeaf98c06c RDI: 0000000000000003
RBP: 00007ffeaf98c510 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000004
R13: 00007ffeaf98c06c R14: 00007ffeaf98c100 R15: 0000000000000000
</TASK>
CPU: 0 PID: 11448 Comm: syz.0.1657 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:orc_find arch/x86/kernel/unwind_orc.c:220 [inline]
RIP: 0010:unwind_next_frame+0x281/0x2990 arch/x86/kernel/unwind_orc.c:494
Code: 8f 48 89 e8 48 c1 e8 03 0f b6 04 18 84 c0 0f 85 fd 21 00 00 8b 6d 00 ff c5 4b 8d 04 64 48 8d 8c 00 84 55 0a 8f 48 8d 44 6d 00 <48> 8d 84 00 84 55 0a 8f 48 3d 7c 6d b4 8f 0f 97 c0 48 89 4c 24 20
RSP: 0018:ffffc900000064d8 EFLAGS: 00000202
RAX: 00000000004528ec RBX: dffffc0000000000 RCX: ffffffff8f94a726
RDX: ffff888023bebc00 RSI: 0000000000080f63 RDI: 000000000009c000
RBP: 0000000000170da4 R08: ffffc90000006670 R09: 000000000000000b
R10: 0000000000000004 R11: 0000000000000100 R12: 0000000000170d9b
R13: 000000000009c001 R14: 0000000000080f63 R15: 0000000000000001
FS: 00007f0c5aeb56c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000049aac000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
<IRQ>
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_slab_alloc+0x6c/0x80 mm/kasan/common.c:329
kasan_slab_alloc include/linux/kasan.h:188 [inline]
slab_post_alloc_hook+0x6a/0x4d0 mm/slab.h:767
slab_alloc_node mm/slub.c:3495 [inline]
slab_alloc mm/slub.c:3503 [inline]
__kmem_cache_alloc_lru mm/slub.c:3510 [inline]
kmem_cache_alloc+0x17e/0x2c0 mm/slub.c:3519
dst_alloc+0x105/0x170 net/core/dst.c:90
rt_dst_alloc net/ipv4/route.c:1662 [inline]
__mkroute_output net/ipv4/route.c:2626 [inline]
ip_route_output_key_hash_rcu+0x14a2/0x2350 net/ipv4/route.c:2848
ip_route_output_key_hash+0x1f3/0x330 net/ipv4/route.c:2677
__ip_route_output_key include/net/route.h:134 [inline]
ip_route_output_flow+0x2a/0x150 net/ipv4/route.c:2905
ip_route_output_ports include/net/route.h:171 [inline]
__ip_queue_xmit+0x92e/0x1960 net/ipv4/ip_output.c:496
__tcp_transmit_skb+0x1dd6/0x3470 net/ipv4/tcp_output.c:1427
tcp_rcv_established+0x132c/0x1d70 net/ipv4/tcp_input.c:6144
tcp_v4_do_rcv+0x6d3/0xba0 net/ipv4/tcp_ipv4.c:1735
tcp_v4_rcv+0x2358/0x2a60 net/ipv4/tcp_ipv4.c:2167
ip_protocol_deliver_rcu+0x20a/0x3f0 net/ipv4/ip_input.c:205
ip_local_deliver_finish+0x2c3/0x510 net/ipv4/ip_input.c:233
NF_HOOK+0x32d/0x3b0 include/linux/netfilter.h:304
dst_input include/net/dst.h:477 [inline]
ip_sublist_rcv_finish net/ipv4/ip_input.c:580 [inline]
ip_list_rcv_finish net/ipv4/ip_input.c:631 [inline]
ip_sublist_rcv+0xa36/0xd60 net/ipv4/ip_input.c:639
ip_list_rcv+0x3ed/0x440 net/ipv4/ip_input.c:674
__netif_receive_skb_list_ptype net/core/dev.c:5689 [inline]
__netif_receive_skb_list_core+0x2d9/0x770 net/core/dev.c:5727
__netif_receive_skb_list net/core/dev.c:5789 [inline]
netif_receive_skb_list_internal+0x943/0xca0 net/core/dev.c:5880
gro_normal_list include/net/gro.h:451 [inline]
gro_normal_one include/net/gro.h:464 [inline]
napi_skb_finish net/core/gro.c:580 [inline]
napi_gro_receive+0x553/0xaf0 net/core/gro.c:610
receive_buf+0x219d/0x37a0 drivers/net/virtio_net.c:1870
virtnet_receive drivers/net/virtio_net.c:2155 [inline]
virtnet_poll+0x60e/0x11e0 drivers/net/virtio_net.c:2229
__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 kernel/softirq.c:612 [inline]
invoke_softirq kernel/softirq.c:452 [inline]
__irq_exit_rcu+0xd3/0x190 kernel/softirq.c:661
irq_exit_rcu+0x9/0x20 kernel/softirq.c:673
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline]
sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1088
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:finish_task_switch+0x267/0x8f0 kernel/sched/core.c:5255
Code: 2e 09 85 c0 0f 84 30 01 00 00 48 85 db 0f 85 4f 01 00 00 0f 1f 44 00 00 4c 89 e7 e8 43 32 38 09 e8 8e 0a 30 00 fb 4c 8b 65 b8 <49> 8d bc 24 f8 15 00 00 48 89 f8 48 c1 e8 03 42 0f b6 04 30 84 c0
RSP: 0018:ffffc900030c7460 EFLAGS: 00000286
RAX: 128e25a5d7537d00 RBX: 0000000000000000 RCX: 128e25a5d7537d00
RDX: dffffc0000000000 RSI: ffffffff8acacb60 RDI: ffffffff8b1cfa20
RBP: ffffc900030c74b0 R08: ffffffff911e7537 R09: 1ffffffff223cea6
R10: dffffc0000000000 R11: fffffbfff223cea7 R12: ffff888023bebc00
R13: 1ffff110171c79a9 R14: dffffc0000000000 R15: ffff8880b8e3cd48
context_switch kernel/sched/core.c:5384 [inline]
__schedule+0x15b6/0x4660 kernel/sched/core.c:6700
preempt_schedule_common+0x82/0xc0 kernel/sched/core.c:6867
preempt_schedule+0xc0/0xd0 kernel/sched/core.c:6891
preempt_schedule_thunk+0x1a/0x30 arch/x86/entry/thunk_64.S:45
__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
_raw_spin_unlock_irqrestore+0x111/0x120 kernel/locking/spinlock.c:194
rcu_report_exp_rnp kernel/rcu/tree_exp.h:225 [inline]
rcu_preempt_deferred_qs_irqrestore+0x85e/0xc30 kernel/rcu/tree_plugin.h:570
rcu_read_unlock_special+0x3ca/0x4d0 kernel/rcu/tree_plugin.h:762
__rcu_read_unlock+0x7c/0xd0 kernel/rcu/tree_plugin.h:426
rcu_read_unlock include/linux/rcupdate.h:818 [inline]
mt_find+0x3fe/0x640 lib/maple_tree.c:6567
find_vma+0x134/0x1b0 mm/mmap.c:1888
lock_mm_and_find_vma+0x5f/0x2f0 mm/memory.c:5443
do_user_addr_fault+0x36b/0x12d0 arch/x86/mm/fault.c:1343
handle_page_fault arch/x86/mm/fault.c:1463 [inline]
exc_page_fault+0x64/0x100 arch/x86/mm/fault.c:1516
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:608
RIP: 0010:__put_user_4+0x11/0x20 arch/x86/lib/putuser.S:89
Code: 01 ca c3 90 90 90 90 90 90 f3 0f 1e fa 0f 01 cb 66 89 01 31 c9 0f 01 ca c3 f3 0f 1e fa 48 89 cb 48 c1 fb 3f 48 09 d9 0f 01 cb <89> 01 31 c9 0f 01 ca c3 90 90 90 90 90 90 90 f3 0f 1e fa 0f 01 cb
RSP: 0018:ffffc900030c7e80 EFLAGS: 00050246
RAX: 000000000000000b RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff8acadce0 RDI: ffffffff8b1cfa20
RBP: 000000000000000b R08: ffffffff8e8c6b2f R09: 1ffffffff1d18d65
R10: dffffc0000000000 R11: fffffbfff1d18d66 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000001 R15: 0000000000000001
__sys_socketpair+0xb8/0x550 net/socket.c:1765
__do_sys_socketpair net/socket.c:1831 [inline]
__se_sys_socketpair net/socket.c:1828 [inline]
__x64_sys_socketpair+0x9b/0xb0 net/socket.c:1828
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: 0033:0x7f0c59f9de99
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:00007f0c5aeb5028 EFLAGS: 00000246 ORIG_RAX: 0000000000000035
RAX: ffffffffffffffda RBX: 00007f0c5a225fa0 RCX: 00007f0c59f9de99
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000001
RBP: 00007f0c5a033eaf R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f0c5a226038 R14: 00007f0c5a225fa0 R15: 00007ffd43934a38
</TASK>
---
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