syzbot

 sign-in | mailing list | source | docs
🐞 Open [904]
🐞 Fixed [143]
🐞 Invalid [1088]
⬇ Missing Backports [73]
≡ Crashes
Kernel Health Bugs/Month Bug Lifetimes Fuzzing
💬 Send us feedback

INFO: rcu detected stall in mrp_join_timer (3)

Status: upstream: reported on 2026/05/01 08:15
Reported-by: syzbot+cb6d0aaf7ecff4d68410@syzkaller.appspotmail.com
First crash: 1d10h, last: 1d10h
▶ ▼ Similar bugs (13)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in mrp_join_timer (4) net 1 10 572d 701d 0/29 auto-obsoleted due to no activity on 2025/01/05 17:43
linux-6.1 INFO: rcu detected stall in mrp_join_timer 1 1 631d 631d 0/3 auto-obsoleted due to no activity on 2024/11/17 18:10
linux-6.1 INFO: rcu detected stall in mrp_join_timer (2) 1 1 159d 159d 0/3 auto-obsoleted due to no activity on 2026/03/04 01:39
linux-4.14 INFO: rcu detected stall in mrp_join_timer 1 7 2143d 2308d 0/1 auto-closed as invalid on 2020/10/17 01:22
upstream INFO: rcu detected stall in mrp_join_timer net 1 1 2306d 2306d 0/29 closed as invalid on 2020/01/09 08:13
linux-4.19 INFO: rcu detected stall in mrp_join_timer 1 28 1994d 2306d 0/1 auto-closed as invalid on 2021/03/15 12:15
upstream INFO: rcu detected stall in mrp_join_timer (3) net 1 1 864d 864d 0/29 closed as invalid on 2024/02/01 10:31
upstream INFO: rcu detected stall in mrp_join_timer (2) net 1 57 1518d 2267d 0/29 auto-closed as invalid on 2022/07/04 18:27
upstream BUG: soft lockup in mrp_join_timer (4) net 1 1 276d 276d 0/29 closed as invalid on 2025/09/01 08:24
linux-4.14 BUG: soft lockup in mrp_join_timer 1 1 1867d 1867d 0/1 auto-closed as invalid on 2021/07/20 15:25
upstream BUG: soft lockup in mrp_join_timer (2) net 1 1 943d 943d 0/29 closed as invalid on 2023/11/01 18:32
linux-4.19 BUG: soft lockup in mrp_join_timer (2) 1 58 1164d 1841d 0/1 upstream: reported on 2021/04/16 18:29
upstream BUG: soft lockup in mrp_join_timer (3) net 1 2 362d 366d 0/29 closed as invalid on 2025/06/11 12:25

Sample crash report:
rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { 1-.... } 2660 jiffies s: 49793 root: 0x2/.
rcu: blocking rcu_node structures (internal RCU debug):
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 16717 Comm: syz.0.4023 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
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_const_cmp8+0x1b/0x80 kernel/kcov.c:320
Code: 7c 11 10 48 89 74 11 18 48 89 44 11 20 c3 90 48 8b 04 24 65 48 8b 0d 04 f6 7f 7e 65 8b 15 05 f6 7f 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
RSP: 0018:ffffc900001dff78 EFLAGS: 00000006
RAX: ffffffff8100fdbd RBX: 1ffff9200003c021 RCX: ffff88805c658000
RDX: 0000000000000100 RSI: ffffffff8171c074 RDI: 0000000000000000
RBP: ffffc900001e00b0 R08: ffffc900001e0aa0 R09: ffffc900001e0030
R10: dffffc0000000000 R11: fffff5200003c008 R12: ffffc900001e010c
R13: ffffc900001dffe0 R14: ffffffff8171c074 R15: 1ffff9200003bff8
FS:  00007f87344186c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000100000000 CR3: 0000000076f7a000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000200000000300 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff3 DR7: 0000000000000600
Call Trace:
 <IRQ>
 perf_callchain_kernel+0x30d/0x680 arch/x86/events/core.c:2807
 get_perf_callchain+0x236/0x490 kernel/events/callchain.c:204
 perf_callchain kernel/events/core.c:7512 [inline]
 perf_prepare_sample+0x399/0x2020 kernel/events/core.c:7545
 __perf_event_output kernel/events/core.c:7730 [inline]
 perf_event_output_forward+0x197/0x2f0 kernel/events/core.c:7750
 __perf_event_overflow+0x448/0x610 kernel/events/core.c:9496
 perf_swevent_overflow kernel/events/core.c:9579 [inline]
 perf_swevent_event+0x315/0x570 kernel/events/core.c:9630
 perf_tp_event+0x3e7/0xc30 kernel/events/core.c:10064
 perf_trace_run_bpf_submit+0xf3/0x1c0 kernel/events/core.c:10032
 perf_trace_preemptirq_template+0x268/0x320 include/trace/events/preemptirq.h:14
 trace_irq_enable_rcuidle+0xd3/0x140 include/trace/events/preemptirq.h:40
 trace_hardirqs_on+0x24/0x40 kernel/trace/trace_preemptirq.c:44
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0xbc/0x120 kernel/locking/spinlock.c:194
Code: c7 44 24 20 00 00 00 00 9c 8f 44 24 20 f7 44 24 20 00 02 00 00 41 c6 04 07 f8 75 4b f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 <e8> 2f ed 20 f7 65 8b 05 80 70 ca 75 85 c0 74 3c 48 c7 04 24 0e 36
RSP: 0018:ffffc900001e09a0 EFLAGS: 00000206
RAX: dffffc0000000004 RBX: 0000000000000a02 RCX: b001b454cc0f8300
RDX: dffffc0000000000 RSI: ffffffff8a8c1120 RDI: 0000000000000001
RBP: ffffc900001e0a20 R08: ffffffff90af9327 R09: 1ffffffff215f264
R10: dffffc0000000000 R11: fffffbfff215f265 R12: dffffc0000000000
R13: ffff88806400d230 R14: ffffffff96e52260 R15: 1ffff9200003c134
 debug_object_assert_init+0x1ed/0x2f0 lib/debugobjects.c:889
 debug_timer_assert_init kernel/time/timer.c:792 [inline]
 debug_assert_init kernel/time/timer.c:837 [inline]
 __mod_timer+0x54/0xd00 kernel/time/timer.c:1020
 mrp_join_timer_arm net/802/mrp.c:596 [inline]
 mrp_join_timer+0x13b/0x170 net/802/mrp.c:611
 call_timer_fn+0x1ac/0x670 kernel/time/timer.c:1701
 expire_timers kernel/time/timer.c:1752 [inline]
 __run_timers+0x53e/0x800 kernel/time/timer.c:2023
 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:2036
 handle_softirqs+0x2a1/0x930 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:preempt_schedule_irq+0xb6/0x160 kernel/sched/core.c:6874
Code: 00 00 43 c6 44 37 04 f8 74 0b 0f 0b 48 f7 03 08 00 00 00 74 7f bf 01 00 00 00 e8 15 64 22 f7 e8 10 58 52 f7 fb bf 01 00 00 00 <e8> 75 b9 ff ff 43 c6 44 37 08 00 48 c7 44 24 40 00 00 00 00 9c 8f
RSP: 0018:ffffc9000ca9fb80 EFLAGS: 00000282
RAX: b001b454cc0f8300 RBX: 0000000000000000 RCX: b001b454cc0f8300
RDX: dffffc0000000000 RSI: ffffffff8a8c1120 RDI: 0000000000000001
RBP: ffffc9000ca9fc20 R08: ffff8880b8f3580b R09: 1ffff110171e6b01
R10: dffffc0000000000 R11: ffffed10171e6b02 R12: 0000000000000000
R13: 0000000000000000 R14: dffffc0000000000 R15: 1ffff92001953f70
 irqentry_exit+0x63/0x70 kernel/entry/common.c:439
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:__ref_is_percpu include/linux/percpu-refcount.h:174 [inline]
RIP: 0010:percpu_ref_tryget_many include/linux/percpu-refcount.h:243 [inline]
RIP: 0010:percpu_ref_tryget+0x8e/0x180 include/linux/percpu-refcount.h:266
Code: 61 98 8a be 19 03 00 00 48 c7 c2 40 61 98 8a e8 08 1a 8a ff 49 bf 00 00 00 00 00 fc ff df 4c 89 f0 48 c1 e8 03 42 80 3c 38 00 <74> 08 4c 89 f7 e8 48 ad f8 ff 49 8b 06 a8 03 75 67 65 48 ff 00 40
RSP: 0018:ffffc9000ca9fce8 EFLAGS: 00000246
RAX: 1ffff110048f3c00 RBX: ffffffff81dad3c5 RCX: b001b454cc0f8300
RDX: 0000000000000000 RSI: ffffffff8adf1300 RDI: ffffffff8adf12c0
RBP: 0000000000000cc0 R08: dffffc0000000000 R09: 1ffffffff215f248
R10: dffffc0000000000 R11: fffffbfff215f249 R12: ffff88814011c860
R13: 0000000000000580 R14: ffff88802479e000 R15: dffffc0000000000
 obj_cgroup_tryget include/linux/memcontrol.h:779 [inline]
 __get_obj_cgroup_from_memcg+0x70/0xe0 mm/memcontrol.c:3004
 get_obj_cgroup_from_current+0x16b/0x280 mm/memcontrol.c:3024
 memcg_slab_pre_alloc_hook mm/slab.h:485 [inline]
 slab_pre_alloc_hook+0x91/0x310 mm/slab.h:715
 slab_alloc_node mm/slub.c:3279 [inline]
 slab_alloc mm/slub.c:3367 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3374 [inline]
 kmem_cache_alloc_lru+0x49/0x2e0 mm/slub.c:3390
 alloc_inode_sb include/linux/fs.h:3245 [inline]
 sock_alloc_inode+0x24/0xc0 net/socket.c:306
 alloc_inode fs/inode.c:261 [inline]
 new_inode_pseudo+0x5f/0x1c0 fs/inode.c:1063
 sock_alloc net/socket.c:631 [inline]
 __sock_create+0x129/0x940 net/socket.c:1513
 sock_create net/socket.c:1605 [inline]
 __sys_socket_create net/socket.c:1642 [inline]
 __sys_socket+0xc4/0x190 net/socket.c:1670
 __do_sys_socket net/socket.c:1683 [inline]
 __se_sys_socket net/socket.c:1681 [inline]
 __x64_sys_socket+0x76/0x80 net/socket.c:1681
 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: 0033:0x7f873359cdd9
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:00007f8734418028 EFLAGS: 00000246 ORIG_RAX: 0000000000000029
RAX: ffffffffffffffda RBX: 00007f8733815fa0 RCX: 00007f873359cdd9
RDX: 0000000000000000 RSI: 0000000000000002 RDI: 000000000000000a
RBP: 00007f8733632d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f8733816038 R14: 00007f8733815fa0 R15: 00007fff2e7b9c08
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/05/01 08:14 linux-6.1.y 4931e0e1673d 753c55b9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in mrp_join_timer
* Struck through repros no longer work on HEAD.