Hello,
syzbot found the following issue on:
HEAD commit: 5fa4793a2d2d Linux 6.6.119
git tree: linux-6.6.y
console output:
https://syzkaller.appspot.com/x/log.txt?x=1616ceb4580000
kernel config:
https://syzkaller.appspot.com/x/.config?x=691a6769a86ac817
dashboard link:
https://syzkaller.appspot.com/bug?extid=91acdce0974486dbd973
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image:
https://storage.googleapis.com/syzbot-assets/63699875f1dd/disk-5fa4793a.raw.xz
vmlinux:
https://storage.googleapis.com/syzbot-assets/8506652fcb6f/vmlinux-5fa4793a.xz
kernel image:
https://storage.googleapis.com/syzbot-assets/1b30ceed1710/bzImage-5fa4793a.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by:
syzbot+91acdc...@syzkaller.appspotmail.com
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P16210/2:b..l
rcu: (detected by 0, t=10502 jiffies, g=102241, q=107 ncpus=2)
task:syz.2.3025 state:R running task stack:27176 pid:16210 ppid:13705 flags:0x00004000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5380 [inline]
__schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
preempt_schedule_irq+0xb5/0x140 kernel/sched/core.c:7009
irqentry_exit+0x67/0x70 kernel/entry/common.c:438
asm_sysvec_reschedule_ipi+0x1a/0x20 arch/x86/include/asm/idtentry.h:692
RIP: 0010:__rcu_read_unlock+0xa/0xd0 kernel/rcu/tree_plugin.h:419
Code: 80 e1 07 80 c1 03 38 c1 7c e3 48 89 df e8 8e 99 6c 00 eb d9 66 2e 0f 1f 84 00 00 00 00 00 66 90 f3 0f 1e fa 41 57 41 56 41 55 <41> 54 53 49 bf 00 00 00 00 00 fc ff df 65 48 8b 3d 91 50 93 7e 48
RSP: 0018:ffffc90003627340 EFLAGS: 00000202
RAX: 0000000000000001 RBX: ffffffff81e4d3b5 RCX: fd82e98a8dd44300
RDX: 0000000000000000 RSI: ffffffff8afc6f60 RDI: ffffffff8afc6f20
RBP: 1ffff11003de1201 R08: dffffc0000000000 R09: 1ffffffff21b28a0
R10: dffffc0000000000 R11: fffffbfff21b28a1 R12: ffff888023e9c054
R13: dffffc0000000000 R14: ffff888023e9c010 R15: dffffc0000000000
rcu_read_unlock include/linux/rcupdate.h:818 [inline]
percpu_ref_tryget_many include/linux/percpu-refcount.h:250 [inline]
percpu_ref_tryget+0xee/0x180 include/linux/percpu-refcount.h:266
css_tryget include/linux/cgroup_refcnt.h:45 [inline]
get_mem_cgroup_from_mm+0x102/0x290 mm/memcontrol.c:1094
__mem_cgroup_charge+0x15/0x80 mm/memcontrol.c:7110
mem_cgroup_charge include/linux/memcontrol.h:686 [inline]
wp_page_copy mm/memory.c:3118 [inline]
do_wp_page+0x14fe/0x3630 mm/memory.c:3469
handle_pte_fault mm/memory.c:5063 [inline]
__handle_mm_fault mm/memory.c:5188 [inline]
handle_mm_fault+0x12d4/0x4920 mm/memory.c:5353
do_user_addr_fault+0x738/0x12e0 arch/x86/mm/fault.c:1373
handle_page_fault arch/x86/mm/fault.c:1465 [inline]
exc_page_fault+0x67/0x110 arch/x86/mm/fault.c:1521
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:608
RIP: 0010:__put_user_nocheck_4+0x7/0x10 arch/x86/lib/putuser.S:98
Code: 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 <89> 01 31 c9 0f 01 ca c3 90 f3 0f 1e fa 48 89 cb 48 c1 fb 3f 48 09
RSP: 0018:ffffc900036278d8 EFLAGS: 00050202
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 000020000001b030
RDX: ffff88802d45bc00 RSI: 0000000000000002 RDI: 00000000ffffffff
RBP: ffffc90003627a70 R08: ffffc90003627687 R09: 1ffff920006c4ed0
R10: dffffc0000000000 R11: fffff520006c4ed1 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000002 R15: 000020000001b000
____sys_recvmsg+0x388/0x5b0 net/socket.c:2827
___sys_recvmsg+0x1b6/0x510 net/socket.c:2856
do_recvmmsg+0x360/0x7d0 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+0x191/0x240 net/socket.c:3045
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f333938f749
RSP: 002b:00007f333a2d9038 EFLAGS: 00000246 ORIG_RAX: 000000000000012b
RAX: ffffffffffffffda RBX: 00007f33395e6090 RCX: 00007f333938f749
RDX: 0000000000010106 RSI: 00002000000000c0 RDI: 0000000000000003
RBP: 00007f3339413f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000002 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f33395e6128 R14: 00007f33395e6090 R15: 00007ffe1c5614a8
</TASK>
rcu: rcu_preempt kthread timer wakeup didn't happen for 10501 jiffies! g102241 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: Possible timer handling issue on cpu=1 timer-softirq=69624
rcu: rcu_preempt kthread starved for 10502 jiffies! g102241 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:27080 pid:17 ppid:2 flags:0x00004000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5380 [inline]
__schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
schedule+0xbd/0x170 kernel/sched/core.c:6773
schedule_timeout+0x160/0x280 kernel/time/timer.c:2168
rcu_gp_fqs_loop+0x302/0x1560 kernel/rcu/tree.c:1667
rcu_gp_kthread+0x99/0x380 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: 16213 Comm: syz.1.3026 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:arch_atomic_read arch/x86/include/asm/atomic.h:23 [inline]
RIP: 0010:raw_atomic_read include/linux/atomic/atomic-arch-fallback.h:444 [inline]
RIP: 0010:rcu_dynticks_curr_cpu_in_eqs include/linux/context_tracking.h:122 [inline]
RIP: 0010:rcu_is_watching+0x5a/0xb0 kernel/rcu/tree.c:700
Code: f0 48 c1 e8 03 42 80 3c 38 00 74 08 4c 89 f7 e8 ac 64 6d 00 48 c7 c3 28 6b 03 00 49 03 1e 48 89 d8 48 c1 e8 03 42 0f b6 04 38 <84> c0 75 2f 8b 03 65 ff 0d a1 1b 94 7e 74 0c 83 e0 04 c1 e8 02 5b
RSP: 0018:ffffc900001f0a00 EFLAGS: 00000806
RAX: 0000000000000000 RBX: ffff8880b8f36b28 RCX: 842488318b4ae000
RDX: 0000000000000000 RSI: ffffffff8afc6f60 RDI: ffffffff8afc6f20
RBP: ffffc900001f0b30 R08: ffffffff8e4a212f R09: 1ffffffff1c94425
R10: dffffc0000000000 R11: fffffbfff1c94426 R12: ffffffff842636a3
R13: dffffc0000000000 R14: ffffffff8c7c8a38 R15: dffffc0000000000
FS: 00007fc0bdd0d6c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c2b2722 CR3: 000000002ee93000 CR4: 00000000003526e0
Call Trace:
<IRQ>
trace_lock_release include/trace/events/lock.h:69 [inline]
lock_release+0xba/0x8b0 kernel/locking/lockdep.c:5765
debug_objects_fill_pool+0xb3/0x6b0 lib/debugobjects.c:617
debug_object_activate+0x36/0x4b0 lib/debugobjects.c:705
debug_hrtimer_activate kernel/time/hrtimer.c:450 [inline]
debug_activate kernel/time/hrtimer.c:505 [inline]
enqueue_hrtimer+0x30/0x370 kernel/time/hrtimer.c:1108
__run_hrtimer kernel/time/hrtimer.c:1767 [inline]
__hrtimer_run_queues+0x637/0xc40 kernel/time/hrtimer.c:1814
hrtimer_interrupt+0x3c9/0x9c0 kernel/time/hrtimer.c:1876
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1077 [inline]
__sysvec_apic_timer_interrupt+0xfb/0x3b0 arch/x86/kernel/apic/apic.c:1094
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline]
sysvec_apic_timer_interrupt+0x9f/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:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0xa9/0x110 kernel/locking/spinlock.c:194
Code: 74 05 e8 0a d9 1a f7 48 c7 44 24 20 00 00 00 00 9c 8f 44 24 20 f6 44 24 21 02 75 4b f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 <e8> e2 53 ea f6 65 8b 05 d3 9a 92 75 85 c0 74 3c 48 c7 04 24 0e 36
RSP: 0018:ffffc9000366eaa0 EFLAGS: 00000206
RAX: 842488318b4ae000 RBX: 0000000000000a02 RCX: 842488318b4ae000
RDX: dffffc0000000000 RSI: ffffffff8aaabce0 RDI: 0000000000000001
RBP: ffffc9000366eb30 R08: ffffffff90d94687 R09: 1ffffffff21b28d0
R10: dffffc0000000000 R11: fffffbfff21b28d1 R12: dffffc0000000000
R13: 000000000000004d R14: ffff888077e4a2e8 R15: 1ffff920006cdd54
spin_unlock_irqrestore include/linux/spinlock.h:406 [inline]
taprio_change+0x44ff/0x5110 net/sched/sch_taprio.c:2013
taprio_init+0x97a/0xbf0 net/sched/sch_taprio.c:2154
qdisc_create+0x8eb/0x1050 net/sched/sch_api.c:1317
tc_modify_qdisc+0xb33/0x1cc0 net/sched/sch_api.c:-1
rtnetlink_rcv_msg+0x7c7/0xf10 net/core/rtnetlink.c:6472
netlink_rcv_skb+0x216/0x480 net/netlink/af_netlink.c:2545
netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
netlink_unicast+0x751/0x8d0 net/netlink/af_netlink.c:1346
netlink_sendmsg+0x8c1/0xbe0 net/netlink/af_netlink.c:1894
sock_sendmsg_nosec net/socket.c:730 [inline]
__sock_sendmsg net/socket.c:745 [inline]
____sys_sendmsg+0x5bf/0x950 net/socket.c:2595
___sys_sendmsg+0x220/0x290 net/socket.c:2649
__sys_sendmsg net/socket.c:2678 [inline]
__do_sys_sendmsg net/socket.c:2687 [inline]
__se_sys_sendmsg+0x1a5/0x270 net/socket.c:2685
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fc0bcd8f749
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fc0bdd0d038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fc0bcfe5fa0 RCX: 00007fc0bcd8f749
RDX: 0000000000000000 RSI: 0000200000000000 RDI: 0000000000000004
RBP: 00007fc0bce13f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc0bcfe6038 R14: 00007fc0bcfe5fa0 R15: 00007ffd8d05deb8
</TASK>
ip6_tunnel: ip6gre1 xmit: Local address not yet configured!
---
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