syzbot


INFO: rcu detected stall in sys_clone (2)

Status: upstream: reported on 2025/12/09 09:13
Reported-by: syzbot+7919861b650883ef99d9@syzkaller.appspotmail.com
First crash: 166d, last: 6d01h
Similar bugs (18)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.6 INFO: rcu detected stall in sys_clone 1 C done 8 200d 285d 2/2 fixed on 2025/12/06 23:11
linux-5.15 INFO: rcu detected stall in sys_clone 1 1 899d 899d 0/3 auto-obsoleted due to no activity on 2024/03/15 18:08
linux-6.1 INFO: rcu detected stall in sys_clone 1 3 1046d 1119d 0/3 auto-obsoleted due to no activity on 2023/10/20 18:18
upstream INFO: rcu detected stall in sys_clone (2) mm 1 49 2273d 2389d 0/29 auto-closed as invalid on 2020/06/01 05:26
upstream INFO: rcu detected stall in sys_clone (4) kernel 1 1 1789d 1789d 0/29 auto-closed as invalid on 2021/09/27 17:49
upstream INFO: rcu detected stall in sys_clone (3) mm 1 2 2125d 2147d 0/29 auto-closed as invalid on 2020/10/26 22:48
upstream INFO: rcu detected stall in sys_clone (6) kasan mm 1 1 1460d 1460d 0/29 auto-closed as invalid on 2022/08/23 03:28
upstream INFO: rcu detected stall in sys_clone kernel 1 1 2446d 2446d 13/29 fixed on 2019/10/09 10:54
upstream INFO: rcu detected stall in sys_clone (8) mm 1 C error 418 23h14m 786d 0/29 upstream: reported C repro on 2024/03/29 00:16
linux-4.19 INFO: rcu detected stall in sys_clone 1 2 2344d 2362d 0/1 auto-closed as invalid on 2020/04/21 05:46
upstream INFO: rcu detected stall in sys_clone (5) kernfs 1 5 1594d 1694d 0/29 closed as invalid on 2022/02/08 10:00
upstream INFO: rcu detected stall in sys_clone (7) fs 1 1 1195d 1195d 0/29 auto-obsoleted due to no activity on 2023/05/14 17:18
linux-5.15 INFO: rcu detected stall in sys_clone (2) missing-backport origin:upstream 1 C done 127 14h13m 788d 0/3 upstream: reported C repro on 2024/03/27 00:16
linux-6.1 INFO: rcu detected stall in sys_clone (2) origin:upstream missing-backport 1 C error 71 1h58m 794d 0/3 upstream: reported C repro on 2024/03/20 15:17
android-5-10 BUG: soft lockup in sys_clone 1 1 685d 685d 0/2 auto-obsoleted due to no activity on 2024/10/06 12:58
android-5-10 BUG: soft lockup in sys_clone (2) 1 1 259d 259d 0/2 auto-obsoleted due to no activity on 2025/12/06 02:03
android-5-10 BUG: soft lockup in sys_clone (3) 1 1 111d 111d 0/2 auto-obsoleted due to no activity on 2026/05/02 19:39
android-5-15 BUG: soft lockup in sys_clone origin:upstream 1 C error 18 621d 764d 0/2 auto-obsoleted due to no activity on 2024/12/19 12:14

Sample crash report:
bridge0: received packet on veth0_to_bridge with own address as source address (addr:66:c3:5f:b7:17:2f, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:66:c3:5f:b7:17:2f, vlan:0)
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P742/1:b..l P27528/1:b..l P739/1:b..l
rcu: 	(detected by 1, t=10503 jiffies, g=226773, q=188 ncpus=2)
task:syz.2.9184      state:R  running task     stack:25448 pid:739   ppid:27786  flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x1553/0x45a0 kernel/sched/core.c:6700
 preempt_schedule_irq+0xbf/0x150 kernel/sched/core.c:7010
 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:check_kcov_mode kernel/kcov.c:193 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x36/0x60 kernel/kcov.c:216
Code: 10 8e 7c 7e 65 8b 15 11 8e 7c 7e 81 e2 00 01 ff 00 74 11 81 fa 00 01 00 00 75 35 83 b9 1c 16 00 00 00 74 2c 8b 91 f8 15 00 00 <83> fa 02 75 21 48 8b 91 00 16 00 00 48 8b 32 48 8d 7e 01 8b 89 fc
RSP: 0018:ffffc90004edf1f8 EFLAGS: 00000246
RAX: ffffffff813b3691 RBX: ffffc90004edf270 RCX: ffff888018fcda00
RDX: 0000000000000002 RSI: 0000000000000001 RDI: 0000000000000000
RBP: 0000000000000001 R08: ffff888018fcda00 R09: 0000000000000003
R10: 0000000000000004 R11: 0000000000000002 R12: ffffffff81df7123
R13: 1ffff110031f9bee R14: dffffc0000000000 R15: 1ffff920009dbe4e
 unwind_get_return_address+0x71/0xc0 arch/x86/kernel/unwind_orc.c:369
 arch_stack_walk+0x11d/0x190 arch/x86/kernel/stacktrace.c:26
 stack_trace_save+0xaa/0x100 kernel/stacktrace.c:122
 save_stack+0x125/0x230 mm/page_owner.c:128
 __reset_page_owner+0x4e/0x190 mm/page_owner.c:149
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1181 [inline]
 free_unref_page_prepare+0x7b2/0x8c0 mm/page_alloc.c:2365
 free_unref_page+0x32/0x2e0 mm/page_alloc.c:2458
 discard_slab mm/slub.c:2127 [inline]
 __unfreeze_partials+0x1cf/0x210 mm/slub.c:2667
 put_cpu_partial+0x17c/0x250 mm/slub.c:2743
 __slab_free+0x319/0x400 mm/slub.c:3700
 qlink_free mm/kasan/quarantine.c:166 [inline]
 qlist_free_all+0x75/0xd0 mm/kasan/quarantine.c:185
 kasan_quarantine_reduce+0x143/0x160 mm/kasan/quarantine.c:292
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:306
 kasan_slab_alloc include/linux/kasan.h:188 [inline]
 slab_post_alloc_hook+0x6e/0x4b0 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+0x11a/0x2d0 mm/slub.c:3519
 vm_area_dup+0x27/0x270 kernel/fork.c:502
 dup_mmap kernel/fork.c:712 [inline]
 dup_mm kernel/fork.c:1694 [inline]
 copy_mm+0xcd5/0x1d80 kernel/fork.c:1743
 copy_process+0x16f7/0x3dc0 kernel/fork.c:2508
 kernel_clone+0x24b/0x8a0 kernel/fork.c:2917
 __do_sys_clone kernel/fork.c:3060 [inline]
 __se_sys_clone kernel/fork.c:3044 [inline]
 __x64_sys_clone+0x1b7/0x230 kernel/fork.c:3044
 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: 0033:0x7fcd73b9ce59
RSP: 002b:00007fcd74a86fd8 EFLAGS: 00000202 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 00007fcd73e15fa0 RCX: 00007fcd73b9ce59
RDX: 0000200000000280 RSI: 0000000000000000 RDI: 0000000004041080
RBP: 00007fcd73c32d6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000
R13: 00007fcd73e16038 R14: 00007fcd73e15fa0 R15: 00007ffc0602dea8
 </TASK>
task:syz-executor    state:R  running task     stack:24232 pid:27528 ppid:5759   flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x1553/0x45a0 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 include/linux/spinlock_api_smp.h:143 [inline]
 _raw_spin_unlock+0x3a/0x40 kernel/locking/spinlock.c:186
 spin_unlock include/linux/spinlock.h:391 [inline]
 zap_pte_range mm/memory.c:1523 [inline]
 zap_pmd_range mm/memory.c:1571 [inline]
 zap_pud_range mm/memory.c:1600 [inline]
 zap_p4d_range mm/memory.c:1621 [inline]
 unmap_page_range+0x2315/0x3000 mm/memory.c:1642
 unmap_vmas+0x286/0x3f0 mm/memory.c:1732
 exit_mmap+0x238/0xb90 mm/mmap.c:3302
 __mmput+0x118/0x3c0 kernel/fork.c:1357
 exit_mm+0x24a/0x350 kernel/exit.c:570
 do_exit+0x8dd/0x2460 kernel/exit.c:871
 do_group_exit+0x21b/0x2d0 kernel/exit.c:1026
 get_signal+0x12fc/0x13f0 kernel/signal.c:2902
 arch_do_signal_or_restart+0xc2/0x800 arch/x86/kernel/signal.c:310
 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302
 do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f5ac3957fd7
RSP: 002b:00007ffc949f1b10 EFLAGS: 00000202 ORIG_RAX: 000000000000003d
RAX: fffffffffffffe00 RBX: 000055555810c500 RCX: 00007f5ac3957fd7
RDX: 0000000040000000 RSI: 00007ffc949f1b6c RDI: ffffffffffffffff
RBP: 00007ffc949f1b6c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000008
R13: 0000000000000003 R14: 00007ffc949f1dc8 R15: 0000000000000000
 </TASK>
task:syz.0.9185      state:R  running task     stack:25448 pid:742   ppid:27550  flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x1553/0x45a0 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 include/linux/spinlock_api_smp.h:143 [inline]
 _raw_spin_unlock+0x3a/0x40 kernel/locking/spinlock.c:186
 spin_unlock include/linux/spinlock.h:391 [inline]
 zap_pte_range mm/memory.c:1523 [inline]
 zap_pmd_range mm/memory.c:1571 [inline]
 zap_pud_range mm/memory.c:1600 [inline]
 zap_p4d_range mm/memory.c:1621 [inline]
 unmap_page_range+0x2315/0x3000 mm/memory.c:1642
 unmap_vmas+0x286/0x3f0 mm/memory.c:1732
 exit_mmap+0x238/0xb90 mm/mmap.c:3302
 __mmput+0x118/0x3c0 kernel/fork.c:1357
 exit_mm+0x24a/0x350 kernel/exit.c:570
 do_exit+0x8dd/0x2460 kernel/exit.c:871
 do_group_exit+0x21b/0x2d0 kernel/exit.c:1026
 get_signal+0x12fc/0x13f0 kernel/signal.c:2902
 arch_do_signal_or_restart+0xc2/0x800 arch/x86/kernel/signal.c:310
 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302
 do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f5ac399ce59
RSP: 002b:00007f5ac4841fd8 EFLAGS: 00000202 ORIG_RAX: 0000000000000038
RAX: fffffffffffffff4 RBX: 00007f5ac3c15fa0 RCX: 00007f5ac399ce59
RDX: 0000200000000280 RSI: 0000000000000000 RDI: 0000000004041080
RBP: 00007f5ac3a32d6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000
R13: 00007f5ac3c16038 R14: 00007f5ac3c15fa0 R15: 00007ffc949f1628
 </TASK>
net_ratelimit: 8815 callbacks suppressed
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:66:c3:5f:b7:17:2f, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:66:c3:5f:b7:17:2f, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:66:c3:5f:b7:17:2f, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
net_ratelimit: 9373 callbacks suppressed
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:66:c3:5f:b7:17:2f, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:66:c3:5f:b7:17:2f, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:66:c3:5f:b7:17:2f, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)

Crashes (11):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/05/18 12:27 linux-6.6.y eac8889a3a1c 55156e84 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: rcu detected stall in sys_clone
2026/05/17 19:24 linux-6.6.y eac8889a3a1c de5aae85 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in sys_clone
2026/04/15 15:40 linux-6.6.y 8cee53b8eaeb c441f497 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: rcu detected stall in sys_clone
2026/04/05 04:57 linux-6.6.y 08667c1437c0 4440e7c2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: rcu detected stall in sys_clone
2026/03/28 07:08 linux-6.6.y c09fbcd31ae6 356bdfc9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in sys_clone
2026/01/25 06:11 linux-6.6.y cbb31f77b879 40acda8a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: rcu detected stall in sys_clone
2026/01/25 00:50 linux-6.6.y cbb31f77b879 40acda8a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: rcu detected stall in sys_clone
2026/01/19 18:52 linux-6.6.y cbb31f77b879 a9fc5226 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: rcu detected stall in sys_clone
2025/12/31 06:17 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in sys_clone
2025/12/12 09:20 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: rcu detected stall in sys_clone
2025/12/09 09:12 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: rcu detected stall in sys_clone
* Struck through repros no longer work on HEAD.