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INFO: rcu detected stall in cleanup_net (8)

Status: upstream: reported C repro on 2026/01/13 16:49
Subsystems: net
Labels: prio:normal
[Documentation on labels]
Reported-by: syzbot+0604401cc084920f6c3d@syzkaller.appspotmail.com
First crash: 463d, last: 8d10h
Cause bisection: failed (error log, bisect log)
  
▶ ▼ ✨ AI Jobs (2)
ID Workflow Result Correct Bug Created Started Finished Revision Error
522574f5-3045-44a4-b782-81de5d9dcb9a assessment-security DenialOfService: ✅ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ✅ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ INFO: rcu detected stall in cleanup_net (8) 2026/05/30 09:49 2026/05/30 09:49 2026/05/30 11:02 6b4a844333e83556da95d61d7f207e7ef5cd4bc6
ad2685a1-374a-4f4c-8229-88360970c29e assessment-security 💥 INFO: rcu detected stall in cleanup_net (8) 2026/05/14 09:34 2026/05/14 09:34 2026/05/14 09:35 6ccb967e465e832a7bfd7a116ad00d52a0923a5d failed to run ["git" "pull" "origin" "HEAD" "--depth=1" "--allow-unrelated-histories"]: exit status 128 From /app/workdir/repo/linux * branch HEAD -> FETCH_HEAD Updating files: 27% (26051/93496) Updating files: 28% (26179/93496) Updating files: 29% (27114/93496) Updating files: 30% (28049/93496) Updating files: 31% (28984/93496) Updating files: 32% (29919/93496) Updating files: 33% (30854/93496) Updating files: 34% (31789/93496) Updating files: 35% (32724/93496) Updating files: 36% (33659/93496) Updating files: 36% (34250/93496) Updating files: 37% (34594/93496) Updating files: 38% (35529/93496) Updating files: 39% (36464/93496) Updating files: 39% (37054/93496) Updating files: 39% (37148/93496) error: unable to write file drivers/gpu/drm/amd/include/asic_reg/gc/gc_11_0_3_sh_mask.h error: unable to write file drivers/gpu/drm/amd/include/asic_reg/gc/gc_11_5_0_offset.h error: unable to write file drivers/gpu/drm/amd/include/asic_reg/gc/gc_11_5_0_sh_mask.h error: unable to write file drivers/gpu/drm/amd/include/asic_reg/gc/gc_12_0_0_offset.h error: unable to write file drivers/gpu/drm/amd/include/asic_reg/gc/gc_12_0_0_sh_mask.h error: unable to write file drivers/gpu/drm/amd/include/asic_reg/gc/gc_12_1_0_offset.h error: unable to write file drivers/gpu/drm/amd/include/asic_reg/gc/gc_12_1_0_sh_mask.h error: unable to write file drivers/gpu/drm/amd/include/asic_reg/gc/gc_9_0_default.h error: unable to write file drivers/gpu/drm/amd/include/asic_reg/gc/gc_9_0_offset.h error: unable to write file drivers/gpu/drm/amd/include/asic_reg/gc/gc_9_0_sh_mask.h error: unable to write file drivers/gpu/drm/amd/include/asic_reg/gc/gc_9_1_offset.h error: unable to write file drivers/gpu/drm/amd/include/asic_reg/gc/gc_9_1_sh_mask.h error: unable to write file drivers/gpu/drm/amd/include/asic_reg/gc/gc_9_2_1_offset.h error: unable to write file drivers/gpu/drm/amd/include/asic_reg/gc/gc_9_2_1_sh_mask.h error: unable to write file drivers/gpu/drm/amd/include/asic_reg/gc/gc_9_4_1_offset.h error: unable to write file drivers/gpu/drm/amd/include/asic_reg/gc/gc_9_4_1_sh_mask.h error: unable to write file drivers/gpu/drm/amd/include/asic_reg/gc/gc_9_4_2_offset.h error: unable to write file drivers/gpu/drm/amd/include/asic_reg/gc/gc_9_4_2_sh_mask.h error: unable to write file drivers/gpu/drm/amd/include/asic_reg/gc/gc_9_4_3_offset.h error: unable to write file drivers/gpu/drm/amd/include/asic_reg/gc/gc_9_4_3_sh_mask.h fatal: cannot create directory at 'drivers/gpu/drm/amd/include/asic_reg/gca': No space left on device
▶ ▼ Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [kernfs?] INFO: rcu detected stall in cleanup_net (8) 0 (1) 2026/01/13 16:49
▶ ▼ Similar bugs (16)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in cleanup_net (3) net 1 1 2455d 2455d 0/29 auto-closed as invalid on 2019/12/15 02:54
upstream INFO: rcu detected stall in cleanup_net (6) net 1 63 1003d 1245d 0/29 closed as invalid on 2023/10/27 14:39
linux-4.19 INFO: rcu detected stall in cleanup_net (2) 1 4 1805d 1937d 0/1 auto-closed as invalid on 2021/10/25 03:43
upstream INFO: rcu detected stall in cleanup_net kernel 1 5 2887d 2955d 0/29 closed as invalid on 2018/09/05 12:51
upstream INFO: rcu detected stall in cleanup_net (4) kernel 1 C done 5 2100d 2096d 15/29 fixed on 2020/10/10 01:52
upstream INFO: rcu detected stall in cleanup_net (5) net 1 24 1584d 1843d 0/29 closed as invalid on 2022/02/08 10:00
linux-4.19 INFO: rcu detected stall in cleanup_net 1 1 2327d 2327d 0/1 auto-closed as invalid on 2020/05/21 02:17
linux-6.1 INFO: rcu detected stall in cleanup_net origin:lts-only 1 syz inconclusive 143 105d 1060d 0/3 upstream: reported syz repro on 2023/07/12 14:45
upstream INFO: rcu detected stall in cleanup_net (2) kernel 1 1 2799d 2795d 0/29 auto-closed as invalid on 2019/04/05 22:14
upstream INFO: rcu detected stall in cleanup_net (7) kernfs rdma bridge 1 15 556d 933d 0/29 auto-obsoleted due to no activity on 2025/02/25 20:50
linux-5.15 INFO: rcu detected stall in cleanup_net origin:lts-only 1 C inconclusive 185 9d20h 1061d 0/3 upstream: reported C repro on 2023/07/11 05:04
android-5-10 BUG: soft lockup in cleanup_net 1 1 394d 394d 0/2 auto-obsoleted due to no activity on 2025/08/06 14:41
linux-4.19 BUG: soft lockup in cleanup_net (2) 1 C 3 1189d 1301d 0/1 upstream: reported C repro on 2022/11/13 07:04
android-5-15 BUG: soft lockup in cleanup_net origin:lts 1 syz 6 635d 762d 0/2 auto-obsoleted due to no activity on 2024/12/08 05:58
android-6-1 BUG: soft lockup in cleanup_net 1 1 505d 505d 0/2 auto-obsoleted due to no activity on 2025/04/17 10:35
linux-4.19 BUG: soft lockup in cleanup_net 1 4 1435d 1648d 0/1 auto-obsoleted due to no activity on 2022/10/30 18:15
▶ ▼ Last patch testing requests (4)
Created Duration User Patch Repo Result
2026/05/02 00:16 34m retest repro linux-next OK log
2026/05/02 00:16 54m retest repro linux-next OK log
2026/02/15 11:32 1h09m retest repro linux-next report log
2026/02/15 11:32 35m retest repro linux-next report log

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1):
 P12/1:b..l
rcu: 	(detected by 0, t=10506 jiffies, g=19777, q=1414 ncpus=2)
task:kworker/u8:0    state:R
  running task    
 stack:24064 pid:12    tgid:12    ppid:2      task_flags:0x4208060 flags:0x00080000
Workqueue: netns cleanup_net

Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5388 [inline]
 __schedule+0x1295/0x67a0 kernel/sched/core.c:7189
 preempt_schedule_irq+0x50/0x90 kernel/sched/core.c:7513
 irqentry_exit_to_kernel_mode_preempt include/linux/irq-entry-common.h:468 [inline]
 irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:539 [inline]
 irqentry_exit+0x205/0x970 kernel/entry/common.c:164
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:its_return_thunk+0x0/0x10 arch/x86/lib/retpoline.S:417
Code: cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc <c3> cc 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 e9 db 3d e9 f5 cc
RSP: 0018:ffffc90000117958 EFLAGS: 00000293

RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffffffff82b93013
RDX: ffff88801e2a4a80 RSI: ffffffff82b930c9 RDI: ffff88801e2a4a80
RBP: ffff88801c6a7800 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000001
R13: ffffffff8d0920c0 R14: 0000000000000000 R15: ffff88802669ce40
 rcu_read_unlock include/linux/rcupdate.h:867 [inline]
 class_rcu_destructor include/linux/rcupdate.h:1181 [inline]
 kernfs_root+0x189/0x2a0 fs/kernfs/kernfs-internal.h:74
 kernfs_remove_by_name_ns+0x30/0x120 fs/kernfs/dir.c:1791
 kernfs_remove_by_name include/linux/kernfs.h:639 [inline]
 remove_files+0x96/0x1c0 fs/sysfs/group.c:28
 sysfs_remove_group+0x8b/0x1b0 fs/sysfs/group.c:328
 br_dev_delete+0x11e/0x1a0 net/bridge/br_if.c:396
 br_net_exit_rtnl+0xdb/0x140 net/bridge/br.c:414
 ops_exit_rtnl_list net/core/net_namespace.c:181 [inline]
 ops_undo_list+0x896/0xab0 net/core/net_namespace.c:248
 cleanup_net+0x499/0x920 net/core/net_namespace.c:702
 process_one_work+0xa0e/0x1980 kernel/workqueue.c:3314
 process_scheduled_works kernel/workqueue.c:3397 [inline]
 worker_thread+0x5ef/0xe50 kernel/workqueue.c:3478
 kthread+0x370/0x450 kernel/kthread.c:436
 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
rcu: rcu_preempt kthread starved for 3761 jiffies! g19777 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
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:R
  running task     stack:28216 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5388 [inline]
 __schedule+0x1295/0x67a0 kernel/sched/core.c:7189
 __schedule_loop kernel/sched/core.c:7268 [inline]
 schedule+0xdd/0x390 kernel/sched/core.c:7283
 schedule_timeout+0x127/0x280 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x1a9/0x900 kernel/rcu/tree.c:2095
 rcu_gp_kthread+0x179/0x230 kernel/rcu/tree.c:2297
 kthread+0x370/0x450 kernel/kthread.c:436
 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 UID: 0 PID: 6574 Comm: syz.0.27 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:write_comp_data+0x40/0x90 kernel/kcov.c:246
Code: 01 12 a9 00 01 ff 00 74 1b f6 c4 01 74 07 a9 00 00 ff 00 74 05 c3 cc cc cc cc 8b 87 ec 16 00 00 85 c0 74 f1 8b 87 c8 16 00 00 <83> f8 03 75 e6 48 8b 87 d0 16 00 00 8b bf cc 16 00 00 48 8b 30 48
RSP: 0018:ffffc90004627648 EFLAGS: 00000246

RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffffffff81fc0d0d
RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffff88801ebf8000
RBP: ffff8880b8540f80 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000003
R13: ffffed10170a81f1 R14: 0000000000000001 R15: ffff8880b843c600
FS:  0000000000000000(0000) GS:ffff888124386000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fffc6cb9d58 CR3: 000000002ea0f000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 csd_lock_wait kernel/smp.c:342 [inline]
 smp_call_function_many_cond+0x5ad/0x1700 kernel/smp.c:892
 on_each_cpu_cond_mask+0x40/0x90 kernel/smp.c:1057
 __flush_tlb_multi arch/x86/include/asm/paravirt.h:46 [inline]
 flush_tlb_multi arch/x86/mm/tlb.c:1361 [inline]
 flush_tlb_mm_range+0x45f/0x16f0 arch/x86/mm/tlb.c:1451
 tlb_flush arch/x86/include/asm/tlb.h:23 [inline]
 tlb_flush_mmu_tlbonly include/asm-generic/tlb.h:509 [inline]
 tlb_flush_mmu_tlbonly include/asm-generic/tlb.h:499 [inline]
 tlb_flush_mmu mm/mmu_gather.c:423 [inline]
 tlb_finish_mmu+0x3fe/0x810 mm/mmu_gather.c:549
 exit_mmap+0x454/0xa10 mm/mmap.c:1313
 __mmput+0x12a/0x410 kernel/fork.c:1178
 mmput+0x67/0x80 kernel/fork.c:1201
 exit_mm kernel/exit.c:582 [inline]
 do_exit+0x8b2/0x2af0 kernel/exit.c:964
 do_group_exit+0xd5/0x2a0 kernel/exit.c:1119
 get_signal+0x20ff/0x2210 kernel/signal.c:3037
 arch_do_signal_or_restart+0x91/0x7e0 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:64 [inline]
 exit_to_user_mode_loop+0x98/0x670 kernel/entry/common.c:98
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline]
 do_syscall_64+0x666/0x870 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe28e59caeb
Code: Unable to access opcode bytes at 0x7fe28e59cac1.
RSP: 002b:00007fe28f4f7f60 EFLAGS: 00000246
 ORIG_RAX: 0000000000000010
RAX: fffffffffffffffc RBX: 00000000ffffff75 RCX: 00007fe28e59caeb
RDX: 00007fe28f4f7fe0 RSI: 0000000040085507 RDI: 0000000000000003
RBP: 0000000000000003 R08: 00007fe28e940320 R09: 0000000000000000
R10: 0000000000000003 R11: 0000000000000246 R12: 00002000000002c0
R13: 0000000000000000 R14: 00007fe28e815fa0 R15: 00007fff186de9c8
 </TASK>

Crashes (32):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/05/28 17:00 upstream eb3f4b7426cf 9a5a7e5e .config console log report syz / log [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: rcu detected stall in cleanup_net
2026/05/29 13:56 upstream 8fde5d1d47f6 6b4a8443 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: rcu detected stall in cleanup_net
2026/04/17 07:42 upstream 3cd8b194bf34 de0a551d .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: rcu detected stall in cleanup_net
2026/04/13 07:12 upstream 028ef9c96e96 38c8e246 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: rcu detected stall in cleanup_net
2026/03/14 00:22 upstream 0257f64bdac7 351cb5cf .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: rcu detected stall in cleanup_net
2026/02/19 13:02 upstream 956b9cbd7f15 746545b8 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: rcu detected stall in cleanup_net
2026/02/01 11:03 upstream 162b42445b58 6b8752f2 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: rcu detected stall in cleanup_net
2026/01/23 18:19 upstream c072629f05d7 1aa92270 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: rcu detected stall in cleanup_net
2026/01/19 10:23 upstream 24d479d26b25 d1b870e1 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: rcu detected stall in cleanup_net
2026/01/18 01:36 upstream d3eeb99bbc99 d1b870e1 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: rcu detected stall in cleanup_net
2026/01/17 08:11 upstream 39d3389331ab d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: rcu detected stall in cleanup_net
2026/01/16 11:38 upstream 983d014aafb1 d1b870e1 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: rcu detected stall in cleanup_net
2026/01/14 06:41 upstream b54345928fa1 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: rcu detected stall in cleanup_net
2026/01/01 01:40 upstream 349bd28a86f2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: rcu detected stall in cleanup_net
2025/12/28 14:19 upstream d26143bb38e2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: rcu detected stall in cleanup_net
2025/12/17 19:59 upstream ea1013c15392 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: rcu detected stall in cleanup_net
2025/12/10 15:06 upstream c9b47175e913 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: rcu detected stall in cleanup_net
2025/12/08 06:41 upstream 67a454e6b1c6 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: rcu detected stall in cleanup_net
2025/11/25 07:12 upstream ac3fd01e4c1e 64219f15 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: rcu detected stall in cleanup_net
2025/11/06 15:55 upstream dc77806cf3b4 4e1406b4 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: rcu detected stall in cleanup_net
2025/08/26 13:35 upstream fab1beda7597 bf27483f .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: rcu detected stall in cleanup_net
2025/07/16 11:40 upstream 155a3c003e55 c118d736 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: rcu detected stall in cleanup_net
2025/06/26 13:27 upstream ee88bddf7f2f 26d77996 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: rcu detected stall in cleanup_net
2025/06/01 06:02 upstream 7d4e49a77d99 3d2f584d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: rcu detected stall in cleanup_net
2025/05/28 15:54 upstream feacb1774bd5 3d2f584d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: rcu detected stall in cleanup_net
2025/05/28 06:08 upstream feacb1774bd5 874a1386 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: rcu detected stall in cleanup_net
2025/05/14 06:04 upstream 9f35e33144ae 7344edeb .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: rcu detected stall in cleanup_net
2025/02/28 01:53 upstream 1e15510b71c9 6a8fcbc4 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: rcu detected stall in cleanup_net
2026/01/01 05:24 linux-next cc3aa43b44bd d6526ea3 .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci-upstream-linux-next-kasan-gce-root INFO: rcu detected stall in cleanup_net
2025/12/21 10:36 linux-next cc3aa43b44bd d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: rcu detected stall in cleanup_net
2025/12/10 14:00 linux-next 008d3547aae5 d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: rcu detected stall in cleanup_net
2025/12/03 13:56 linux-next b2c27842ba85 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: rcu detected stall in cleanup_net
* Struck through repros no longer work on HEAD.