[v6.1] INFO: rcu detected stall in arp_rcv
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syzbot
Aug 1, 2026, 6:48:42 AM (14 days ago) Aug 1
to syzkaller...@googlegroups.com
Hello,
syzbot found the following issue on:
HEAD commit: fb28aa725e05 Linux 6.1.180
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1096cc9e580000
kernel config: https://syzkaller.appspot.com/x/.config?x=31dfefc4a14efea3
dashboard link: https://syzkaller.appspot.com/bug?extid=224b90ffc54cdf1c0d64
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/6980f72dc28a/disk-fb28aa72.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/b6cadb2b40be/vmlinux-fb28aa72.xz
kernel image: https://storage.googleapis.com/syzbot-assets/cdec5b077b58/bzImage-fb28aa72.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+224b90...@syzkaller.appspotmail.com
rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { 0-.... } 2681 jiffies s: 1089 root: 0x1/.
rcu: blocking rcu_node structures (internal RCU debug):
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 4422 Comm: syz.2.15 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:debug_objects_fill_pool+0xa2/0x780 lib/debugobjects.c:653
Code: f3 f3 f3 4a 89 44 33 10 4c 8d 25 00 00 00 00 48 c7 c7 c0 b3 1c 8d 31 f6 ba 01 00 00 00 31 c9 41 b8 01 00 00 00 45 31 c9 41 54 <e8> 19 d6 49 fd 48 83 c4 08 8b 05 9f 91 02 09 3b 05 3d 1d 07 0a 7c
RSP: 0018:ffffc90000007018 EFLAGS: 00000046
RAX: f3f3f3f3f8f8f8f8 RBX: 1ffff92000000e0c RCX: 0000000000000000
RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffffffff8d1cb3c0
RBP: ffffc90000007170 R08: 0000000000000001 R09: 0000000000000000
R10: dffffc0000000000 R11: fffff52000000e20 R12: ffffffff841a2257
R13: ffff88801ff30760 R14: dffffc0000000000 R15: 0000000000000000
FS: 00007ff0b910f6c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000001680 CR3: 0000000059dce000 CR4: 00000000003506f0
DR0: 0000200000000300 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Call Trace:
<IRQ>
debug_object_activate+0x32/0x4f0 lib/debugobjects.c:743
debug_hrtimer_activate kernel/time/hrtimer.c:448 [inline]
debug_activate kernel/time/hrtimer.c:502 [inline]
enqueue_hrtimer+0x37/0x410 kernel/time/hrtimer.c:1097
__run_hrtimer kernel/time/hrtimer.c:1768 [inline]
__hrtimer_run_queues+0x63e/0xc90 kernel/time/hrtimer.c:1815
hrtimer_interrupt+0x399/0x980 kernel/time/hrtimer.c:1877
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1107 [inline]
__sysvec_apic_timer_interrupt+0x153/0x5a0 arch/x86/kernel/apic/apic.c:1124
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
sysvec_apic_timer_interrupt+0x4d/0xc0 arch/x86/kernel/apic/apic.c:1118
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:arp_rcv+0xfe/0x4e0 net/ipv4/arp.c:978
Code: 0c f9 4c 89 f8 48 c1 e8 03 42 0f b6 04 20 84 c0 0f 85 e1 02 00 00 41 8b 2f bf 01 00 00 00 89 ee e8 17 12 bb f8 83 fd 01 75 10 <48> 85 db 0f 84 3f 02 00 00 e8 a4 0e bb f8 eb 29 48 89 df be 20 0a
RSP: 0018:ffffc90000007578 EFLAGS: 00000246
RAX: ffffffff88c71f69 RBX: ffff88802e204280 RCX: 0000000000000100
RDX: ffff88802cae8000 RSI: 0000000000000001 RDI: 0000000000000001
RBP: 0000000000000001 R08: ffff88802e204367 R09: 1ffff11005c4086c
R10: dffffc0000000000 R11: ffffed1005c4086d R12: dffffc0000000000
R13: dffffc0000000000 R14: ffff888145b66000 R15: ffff88802e204364
__netif_receive_skb_list_ptype net/core/dev.c:5667 [inline]
__netif_receive_skb_list_core+0x424/0x770 net/core/dev.c:5700
__netif_receive_skb_list net/core/dev.c:5762 [inline]
netif_receive_skb_list_internal+0x93f/0xca0 net/core/dev.c:5853
gro_normal_list include/net/gro.h:433 [inline]
gro_normal_one include/net/gro.h:446 [inline]
napi_skb_finish net/core/gro.c:633 [inline]
napi_gro_receive+0x4eb/0xb50 net/core/gro.c:663
receive_buf+0x1abc/0x4e00 drivers/net/virtio_net.c:1331
virtnet_receive drivers/net/virtio_net.c:1596 [inline]
virtnet_poll+0x5ed/0x1140 drivers/net/virtio_net.c:1717
__napi_poll+0xbb/0x460 net/core/dev.c:6628
napi_poll net/core/dev.c:6695 [inline]
net_rx_action+0x622/0xbc0 net/core/dev.c:6809
handle_softirqs+0x291/0x910 kernel/softirq.c:596
__do_softirq kernel/softirq.c:630 [inline]
invoke_softirq kernel/softirq.c:470 [inline]
__irq_exit_rcu+0x13b/0x230 kernel/softirq.c:679
irq_exit_rcu+0x5/0x20 kernel/softirq.c:691
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1118
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:__schedule+0x145/0x4030 kernel/sched/core.c:6456
Code: f1 e4 9a f7 48 8b 1b 48 89 d8 48 c1 e8 03 42 80 3c 28 00 74 08 48 89 df e8 d8 e4 9a f7 48 81 3b 9d 6e ac 57 0f 85 ec 11 00 00 <83> 7c 24 40 00 75 44 49 8d 5c 24 18 48 89 d8 48 c1 e8 03 42 0f b6
RSP: 0018:ffffc90002f57420 EFLAGS: 00000246
RAX: 1ffff920005ea000 RBX: ffffc90002f50000 RCX: 0000000000000000
RDX: 0000000000000010 RSI: 0000000000000000 RDI: ffffc90002f57550
RBP: ffffc90002f575b0 R08: ffffc90002f5754f R09: ffffc90002f57540
R10: dffffc0000000000 R11: fffff520005eaeaa R12: ffff88802cae8000
R13: dffffc0000000000 R14: ffffc90002f57540 R15: ffff8880b8e00000
preempt_schedule_notrace+0xd9/0x120 kernel/sched/core.c:6825
preempt_schedule_notrace_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:35
rcu_is_watching+0x76/0xa0 kernel/rcu/tree.c:722
trace_lock_release include/trace/events/lock.h:69 [inline]
lock_release+0xcf/0x920 kernel/locking/lockdep.c:5687
rcu_lock_release include/linux/rcupdate.h:355 [inline]
rcu_read_unlock include/linux/rcupdate.h:824 [inline]
is_bpf_text_address+0x28b/0x2a0 kernel/bpf/core.c:737
kernel_text_address+0x9c/0xd0 kernel/extable.c:125
__kernel_text_address+0x9/0x30 kernel/extable.c:79
unwind_get_return_address+0x49/0x80 arch/x86/kernel/unwind_orc.c:323
arch_stack_walk+0xf2/0x140 arch/x86/kernel/stacktrace.c:26
stack_trace_save+0xa6/0xf0 kernel/stacktrace.c:122
kasan_save_stack mm/kasan/common.c:46 [inline]
kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
__kasan_slab_alloc+0x6b/0x80 mm/kasan/common.c:329
kasan_slab_alloc include/linux/kasan.h:201 [inline]
slab_post_alloc_hook+0x4b/0x490 mm/slab.h:737
slab_alloc_node mm/slub.c:3359 [inline]
slab_alloc mm/slub.c:3367 [inline]
__kmem_cache_alloc_lru mm/slub.c:3374 [inline]
kmem_cache_alloc+0x18b/0x2f0 mm/slub.c:3383
kmem_cache_zalloc include/linux/slab.h:689 [inline]
__alloc_file+0x25/0x230 fs/file_table.c:138
alloc_empty_file+0x90/0x180 fs/file_table.c:187
alloc_file+0x5b/0x5f0 fs/file_table.c:229
alloc_file_pseudo+0x180/0x200 fs/file_table.c:272
sock_alloc_file+0xb3/0x240 net/socket.c:467
sock_map_fd net/socket.c:491 [inline]
__sys_socket+0x12d/0x190 net/socket.c:1679
__do_sys_socket net/socket.c:1684 [inline]
__se_sys_socket net/socket.c:1682 [inline]
__x64_sys_socket+0x76/0x80 net/socket.c:1682
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7ff0b819e019
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:00007ff0b910f028 EFLAGS: 00000246 ORIG_RAX: 0000000000000029
RAX: ffffffffffffffda RBX: 00007ff0b8425fa0 RCX: 00007ff0b819e019
RDX: 0000000000000300 RSI: 0200000000000002 RDI: 0000000000000011
RBP: 00007ff0b823500c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff0b8426038 R14: 00007ff0b8425fa0 R15: 00007ffcf5fcd578
</TASK>
---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.
syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title
If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)
If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report
If you want to undo deduplication, reply with:
#syz undup
syzbot found the following issue on:
HEAD commit: fb28aa725e05 Linux 6.1.180
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1096cc9e580000
kernel config: https://syzkaller.appspot.com/x/.config?x=31dfefc4a14efea3
dashboard link: https://syzkaller.appspot.com/bug?extid=224b90ffc54cdf1c0d64
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/6980f72dc28a/disk-fb28aa72.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/b6cadb2b40be/vmlinux-fb28aa72.xz
kernel image: https://storage.googleapis.com/syzbot-assets/cdec5b077b58/bzImage-fb28aa72.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+224b90...@syzkaller.appspotmail.com
rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { 0-.... } 2681 jiffies s: 1089 root: 0x1/.
rcu: blocking rcu_node structures (internal RCU debug):
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 4422 Comm: syz.2.15 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:debug_objects_fill_pool+0xa2/0x780 lib/debugobjects.c:653
Code: f3 f3 f3 4a 89 44 33 10 4c 8d 25 00 00 00 00 48 c7 c7 c0 b3 1c 8d 31 f6 ba 01 00 00 00 31 c9 41 b8 01 00 00 00 45 31 c9 41 54 <e8> 19 d6 49 fd 48 83 c4 08 8b 05 9f 91 02 09 3b 05 3d 1d 07 0a 7c
RSP: 0018:ffffc90000007018 EFLAGS: 00000046
RAX: f3f3f3f3f8f8f8f8 RBX: 1ffff92000000e0c RCX: 0000000000000000
RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffffffff8d1cb3c0
RBP: ffffc90000007170 R08: 0000000000000001 R09: 0000000000000000
R10: dffffc0000000000 R11: fffff52000000e20 R12: ffffffff841a2257
R13: ffff88801ff30760 R14: dffffc0000000000 R15: 0000000000000000
FS: 00007ff0b910f6c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000001680 CR3: 0000000059dce000 CR4: 00000000003506f0
DR0: 0000200000000300 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Call Trace:
<IRQ>
debug_object_activate+0x32/0x4f0 lib/debugobjects.c:743
debug_hrtimer_activate kernel/time/hrtimer.c:448 [inline]
debug_activate kernel/time/hrtimer.c:502 [inline]
enqueue_hrtimer+0x37/0x410 kernel/time/hrtimer.c:1097
__run_hrtimer kernel/time/hrtimer.c:1768 [inline]
__hrtimer_run_queues+0x63e/0xc90 kernel/time/hrtimer.c:1815
hrtimer_interrupt+0x399/0x980 kernel/time/hrtimer.c:1877
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1107 [inline]
__sysvec_apic_timer_interrupt+0x153/0x5a0 arch/x86/kernel/apic/apic.c:1124
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
sysvec_apic_timer_interrupt+0x4d/0xc0 arch/x86/kernel/apic/apic.c:1118
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:arp_rcv+0xfe/0x4e0 net/ipv4/arp.c:978
Code: 0c f9 4c 89 f8 48 c1 e8 03 42 0f b6 04 20 84 c0 0f 85 e1 02 00 00 41 8b 2f bf 01 00 00 00 89 ee e8 17 12 bb f8 83 fd 01 75 10 <48> 85 db 0f 84 3f 02 00 00 e8 a4 0e bb f8 eb 29 48 89 df be 20 0a
RSP: 0018:ffffc90000007578 EFLAGS: 00000246
RAX: ffffffff88c71f69 RBX: ffff88802e204280 RCX: 0000000000000100
RDX: ffff88802cae8000 RSI: 0000000000000001 RDI: 0000000000000001
RBP: 0000000000000001 R08: ffff88802e204367 R09: 1ffff11005c4086c
R10: dffffc0000000000 R11: ffffed1005c4086d R12: dffffc0000000000
R13: dffffc0000000000 R14: ffff888145b66000 R15: ffff88802e204364
__netif_receive_skb_list_ptype net/core/dev.c:5667 [inline]
__netif_receive_skb_list_core+0x424/0x770 net/core/dev.c:5700
__netif_receive_skb_list net/core/dev.c:5762 [inline]
netif_receive_skb_list_internal+0x93f/0xca0 net/core/dev.c:5853
gro_normal_list include/net/gro.h:433 [inline]
gro_normal_one include/net/gro.h:446 [inline]
napi_skb_finish net/core/gro.c:633 [inline]
napi_gro_receive+0x4eb/0xb50 net/core/gro.c:663
receive_buf+0x1abc/0x4e00 drivers/net/virtio_net.c:1331
virtnet_receive drivers/net/virtio_net.c:1596 [inline]
virtnet_poll+0x5ed/0x1140 drivers/net/virtio_net.c:1717
__napi_poll+0xbb/0x460 net/core/dev.c:6628
napi_poll net/core/dev.c:6695 [inline]
net_rx_action+0x622/0xbc0 net/core/dev.c:6809
handle_softirqs+0x291/0x910 kernel/softirq.c:596
__do_softirq kernel/softirq.c:630 [inline]
invoke_softirq kernel/softirq.c:470 [inline]
__irq_exit_rcu+0x13b/0x230 kernel/softirq.c:679
irq_exit_rcu+0x5/0x20 kernel/softirq.c:691
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1118
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:__schedule+0x145/0x4030 kernel/sched/core.c:6456
Code: f1 e4 9a f7 48 8b 1b 48 89 d8 48 c1 e8 03 42 80 3c 28 00 74 08 48 89 df e8 d8 e4 9a f7 48 81 3b 9d 6e ac 57 0f 85 ec 11 00 00 <83> 7c 24 40 00 75 44 49 8d 5c 24 18 48 89 d8 48 c1 e8 03 42 0f b6
RSP: 0018:ffffc90002f57420 EFLAGS: 00000246
RAX: 1ffff920005ea000 RBX: ffffc90002f50000 RCX: 0000000000000000
RDX: 0000000000000010 RSI: 0000000000000000 RDI: ffffc90002f57550
RBP: ffffc90002f575b0 R08: ffffc90002f5754f R09: ffffc90002f57540
R10: dffffc0000000000 R11: fffff520005eaeaa R12: ffff88802cae8000
R13: dffffc0000000000 R14: ffffc90002f57540 R15: ffff8880b8e00000
preempt_schedule_notrace+0xd9/0x120 kernel/sched/core.c:6825
preempt_schedule_notrace_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:35
rcu_is_watching+0x76/0xa0 kernel/rcu/tree.c:722
trace_lock_release include/trace/events/lock.h:69 [inline]
lock_release+0xcf/0x920 kernel/locking/lockdep.c:5687
rcu_lock_release include/linux/rcupdate.h:355 [inline]
rcu_read_unlock include/linux/rcupdate.h:824 [inline]
is_bpf_text_address+0x28b/0x2a0 kernel/bpf/core.c:737
kernel_text_address+0x9c/0xd0 kernel/extable.c:125
__kernel_text_address+0x9/0x30 kernel/extable.c:79
unwind_get_return_address+0x49/0x80 arch/x86/kernel/unwind_orc.c:323
arch_stack_walk+0xf2/0x140 arch/x86/kernel/stacktrace.c:26
stack_trace_save+0xa6/0xf0 kernel/stacktrace.c:122
kasan_save_stack mm/kasan/common.c:46 [inline]
kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
__kasan_slab_alloc+0x6b/0x80 mm/kasan/common.c:329
kasan_slab_alloc include/linux/kasan.h:201 [inline]
slab_post_alloc_hook+0x4b/0x490 mm/slab.h:737
slab_alloc_node mm/slub.c:3359 [inline]
slab_alloc mm/slub.c:3367 [inline]
__kmem_cache_alloc_lru mm/slub.c:3374 [inline]
kmem_cache_alloc+0x18b/0x2f0 mm/slub.c:3383
kmem_cache_zalloc include/linux/slab.h:689 [inline]
__alloc_file+0x25/0x230 fs/file_table.c:138
alloc_empty_file+0x90/0x180 fs/file_table.c:187
alloc_file+0x5b/0x5f0 fs/file_table.c:229
alloc_file_pseudo+0x180/0x200 fs/file_table.c:272
sock_alloc_file+0xb3/0x240 net/socket.c:467
sock_map_fd net/socket.c:491 [inline]
__sys_socket+0x12d/0x190 net/socket.c:1679
__do_sys_socket net/socket.c:1684 [inline]
__se_sys_socket net/socket.c:1682 [inline]
__x64_sys_socket+0x76/0x80 net/socket.c:1682
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7ff0b819e019
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:00007ff0b910f028 EFLAGS: 00000246 ORIG_RAX: 0000000000000029
RAX: ffffffffffffffda RBX: 00007ff0b8425fa0 RCX: 00007ff0b819e019
RDX: 0000000000000300 RSI: 0200000000000002 RDI: 0000000000000011
RBP: 00007ff0b823500c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff0b8426038 R14: 00007ff0b8425fa0 R15: 00007ffcf5fcd578
</TASK>
---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.
syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title
If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)
If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report
If you want to undo deduplication, reply with:
#syz undup
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