INFO: rcu detected stall in loop_process_work (2)

Status: auto-obsoleted due to no activity on 2026/03/08 05:06
Subsystems: mm
[Documentation on labels]
First crash: 298d, last: 291d
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ID Workflow Result Correct Bug Created Started Finished Revision
b4663c98 repro ❓ INFO: rcu detected stall in loop_process_work (2) 2026/03/07 12:49 2026/03/07 12:49 2026/03/07 12:58 31e9c887
▶ ▼ Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 INFO: rcu detected stall in loop_process_work 1 1 835d 835d 0/3 auto-obsoleted due to no activity on 2024/10/20 21:16
upstream INFO: rcu detected stall in loop_process_work block 1 1 1223d 1223d 0/29 auto-obsoleted due to no activity on 2023/09/18 06:20

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P11033/1:b..l P7085/1:b..l P7119/1:b..l P1963/1:b..l
rcu: 	(detected by 1, t=10502 jiffies, g=64209, q=710 ncpus=2)
task:kworker/u8:8    state:R  running task     stack:22432 pid:1963  tgid:1963  ppid:2      task_flags:0x4388160 flags:0x00080000
Workqueue: loop5 loop_rootcg_workfn
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5258 [inline]
 __schedule+0x14ed/0x5040 kernel/sched/core.c:6866
 preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7193
 irqentry_exit+0x5e3/0x670 kernel/entry/common.c:216
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:lock_acquire+0x222/0x340 kernel/locking/lockdep.c:5872
Code: ff ff ff e8 c0 ca be 09 f7 44 24 08 00 02 00 00 0f 84 3a ff ff ff 65 48 8b 05 da 48 03 11 48 3b 44 24 58 75 33 fb 48 83 c4 60 <5b> 41 5c 41 5d 41 5e 41 5f 5d e9 ff a8 c1 09 cc 48 8d 3d e7 8a 07
RSP: 0018:ffffc900053a6cd8 EFLAGS: 00000286
RAX: 016994aeb77c2b00 RBX: 0000000000000000 RCX: 0000000000000046
RDX: 00000000e52b392f RSI: ffffffff8db80e95 RDI: ffffffff8be082e0
RBP: ffffffff8173fd85 R08: ffffffff8173fd85 R09: ffffffff8e13f2a0
R10: ffffc900053a6e38 R11: ffffffff81acb420 R12: 0000000000000002
R13: ffffffff8e13f2a0 R14: 0000000000000000 R15: 0000000000000246
 rcu_lock_acquire include/linux/rcupdate.h:302 [inline]
 rcu_read_lock include/linux/rcupdate.h:838 [inline]
 class_rcu_constructor include/linux/rcupdate.h:1166 [inline]
 unwind_next_frame+0xc2/0x23d0 arch/x86/kernel/unwind_orc.c:495
 arch_stack_walk+0x11c/0x150 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122
 save_stack+0xf5/0x1f0 mm/page_owner.c:165
 __reset_page_owner+0x71/0x1f0 mm/page_owner.c:320
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1409 [inline]
 free_unref_folios+0xcc0/0x13e0 mm/page_alloc.c:3003
 folios_put_refs+0x584/0x670 mm/swap.c:1002
 folio_batch_release include/linux/pagevec.h:101 [inline]
 shmem_undo_range+0x49e/0x1490 mm/shmem.c:1137
 shmem_truncate_range mm/shmem.c:1249 [inline]
 shmem_fallocate+0x491/0xe70 mm/shmem.c:3698
 lo_fallocate drivers/block/loop.c:261 [inline]
 do_req_filebacked drivers/block/loop.c:432 [inline]
 loop_handle_cmd drivers/block/loop.c:1926 [inline]
 loop_process_work+0x8a7/0x10b0 drivers/block/loop.c:1961
 process_one_work+0x93a/0x15a0 kernel/workqueue.c:3279
 process_scheduled_works kernel/workqueue.c:3362 [inline]
 worker_thread+0x9b0/0xee0 kernel/workqueue.c:3443
 kthread+0x389/0x480 kernel/kthread.c:467
 ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>
task:kworker/u8:24   state:R  running task     stack:21472 pid:7119  tgid:7119  ppid:2      task_flags:0x4208060 flags:0x00080000
Workqueue: bat_events batadv_iv_send_outstanding_bat_ogm_packet
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5258 [inline]
 __schedule+0x14ed/0x5040 kernel/sched/core.c:6866
 preempt_schedule_notrace+0x57/0x90 kernel/sched/core.c:7143
 preempt_schedule_notrace_thunk+0x16/0x30 arch/x86/entry/thunk.S:13
 rcu_is_watching+0x7f/0xb0 kernel/rcu/tree.c:753
 rcu_read_unlock include/linux/rcupdate.h:866 [inline]
 batadv_iv_ogm_slide_own_bcast_window net/batman-adv/bat_iv_ogm.c:778 [inline]
 batadv_iv_ogm_schedule_buff net/batman-adv/bat_iv_ogm.c:833 [inline]
 batadv_iv_ogm_schedule+0x68c/0xf00 net/batman-adv/bat_iv_ogm.c:873
 batadv_iv_send_outstanding_bat_ogm_packet+0x6c6/0x7e0 net/batman-adv/bat_iv_ogm.c:1709
 process_one_work+0x93a/0x15a0 kernel/workqueue.c:3279
 process_scheduled_works kernel/workqueue.c:3362 [inline]
 worker_thread+0x9b0/0xee0 kernel/workqueue.c:3443
 kthread+0x389/0x480 kernel/kthread.c:467
 ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>
task:kworker/u8:22   state:R  running task     stack:22776 pid:7085  tgid:7085  ppid:2      task_flags:0x4208060 flags:0x00080000
Workqueue: events_unbound cfg80211_wiphy_work
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5258 [inline]
 __schedule+0x14ed/0x5040 kernel/sched/core.c:6866
 preempt_schedule_notrace+0x57/0x90 kernel/sched/core.c:7143
 preempt_schedule_notrace_thunk+0x16/0x30 arch/x86/entry/thunk.S:13
 rcu_is_watching+0x7f/0xb0 kernel/rcu/tree.c:753
 rcu_read_unlock include/linux/rcupdate.h:866 [inline]
 class_rcu_destructor include/linux/rcupdate.h:1166 [inline]
 unwind_next_frame+0x1a6d/0x23d0 arch/x86/kernel/unwind_orc.c:695
 arch_stack_walk+0x11c/0x150 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122
 save_stack+0xf5/0x1f0 mm/page_owner.c:165
 __set_page_owner+0x8d/0x4c0 mm/page_owner.c:341
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x23d/0x2a0 mm/page_alloc.c:1860
 prep_new_page mm/page_alloc.c:1868 [inline]
 get_page_from_freelist+0x23a5/0x2440 mm/page_alloc.c:3918
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5227
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2486
 alloc_slab_page mm/slub.c:3075 [inline]
 allocate_slab+0x86/0x3b0 mm/slub.c:3248
 new_slab mm/slub.c:3302 [inline]
 ___slab_alloc+0xe53/0x1820 mm/slub.c:4656
 __slab_alloc+0x65/0x100 mm/slub.c:4779
 __slab_alloc_node mm/slub.c:4855 [inline]
 slab_alloc_node mm/slub.c:5255 [inline]
 __do_kmalloc_node mm/slub.c:5660 [inline]
 __kmalloc_noprof+0x47d/0x800 mm/slub.c:5673
 kmalloc_noprof include/linux/slab.h:961 [inline]
 kzalloc_noprof include/linux/slab.h:1094 [inline]
 ieee802_11_parse_elems_full+0x152/0x2ab0 net/mac80211/parse.c:1031
 ieee802_11_parse_elems net/mac80211/ieee80211_i.h:2469 [inline]
 ieee80211_rx_mgmt_probe_beacon net/mac80211/ibss.c:1571 [inline]
 ieee80211_ibss_rx_queued_mgmt+0x48e/0x2af0 net/mac80211/ibss.c:1602
 ieee80211_iface_process_skb net/mac80211/iface.c:1736 [inline]
 ieee80211_iface_work+0x85f/0x12d0 net/mac80211/iface.c:1790
 cfg80211_wiphy_work+0x2ab/0x450 net/wireless/core.c:438
 process_one_work+0x93a/0x15a0 kernel/workqueue.c:3279
 process_scheduled_works kernel/workqueue.c:3362 [inline]
 worker_thread+0x9b0/0xee0 kernel/workqueue.c:3443
 kthread+0x389/0x480 kernel/kthread.c:467
 ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>
task:syz-executor    state:R  running task     stack:21344 pid:11033 tgid:11033 ppid:11027  task_flags:0x400140 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5258 [inline]
 __schedule+0x14ed/0x5040 kernel/sched/core.c:6866
 preempt_schedule_common+0x83/0xd0 kernel/sched/core.c:7050
 preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12
 __raw_spin_unlock include/linux/spinlock_api_smp.h:143 [inline]
 _raw_spin_unlock+0x3f/0x50 kernel/locking/spinlock.c:186
 spin_unlock include/linux/spinlock.h:391 [inline]
 copy_pte_range mm/memory.c:1331 [inline]
 copy_pmd_range+0x74f2/0x7e00 mm/memory.c:1392
 copy_pud_range mm/memory.c:1429 [inline]
 copy_p4d_range mm/memory.c:1453 [inline]
 copy_page_range+0xb88/0x11d0 mm/memory.c:1535
 dup_mmap+0xf4a/0x1b80 mm/mmap.c:1827
 dup_mm kernel/fork.c:1529 [inline]
 copy_mm+0x13c/0x4b0 kernel/fork.c:1581
 copy_process+0x1812/0x3ba0 kernel/fork.c:2218
 kernel_clone+0x21e/0x820 kernel/fork.c:2648
 __do_sys_clone kernel/fork.c:2789 [inline]
 __se_sys_clone kernel/fork.c:2773 [inline]
 __x64_sys_clone+0x18b/0x1e0 kernel/fork.c:2773
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f6390585e93
RSP: 002b:00007fffc3870628 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f6390585e93
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011
RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000001
R10: 000055556b7a47d0 R11: 0000000000000246 R12: 0000000000000000
R13: 00000000000927c0 R14: 000000000008ea3c R15: 00007fffc38707c0
 </TASK>
rcu: rcu_preempt kthread starved for 10633 jiffies! g64209 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->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:R  running task     stack:27480 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5258 [inline]
 __schedule+0x14ed/0x5040 kernel/sched/core.c:6866
 __schedule_loop kernel/sched/core.c:6948 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:6963
 schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x301/0x11b0 kernel/rcu/tree.c:2095
 rcu_gp_kthread+0x9b/0x2d0 kernel/rcu/tree.c:2297
 kthread+0x389/0x480 kernel/kthread.c:467
 ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:pv_native_safe_halt+0x13/0x20 arch/x86/kernel/paravirt.c:82
Code: cc cc cc cc cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d 43 8e 2b 00 f3 0f 1e fa fb f4 <c3> cc cc cc cc cc cc cc cc cc cc cc cc 90 90 90 90 90 90 90 90 90
RSP: 0000:ffffc90000197e20 EFLAGS: 000002c2
RAX: 00000000011f53c7 RBX: ffffffff819717be RCX: 0000000080000001
RDX: 0000000000000001 RSI: ffffffff8d99cce1 RDI: ffffffff8be082e0
RBP: ffffc90000197f10 R08: ffff8880b873375b R09: 1ffff110170e66eb
R10: dffffc0000000000 R11: ffffed10170e66ec R12: ffffffff8fa23d70
R13: 1ffff11003b56b58 R14: 0000000000000001 R15: 0000000000000001
FS:  0000000000000000(0000) GS:ffff888125d0c000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f3428f7070a CR3: 000000005fad4000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline]
 default_idle+0x13/0x20 arch/x86/kernel/process.c:767
 default_idle_call+0x73/0xb0 kernel/sched/idle.c:122
 cpuidle_idle_call kernel/sched/idle.c:191 [inline]
 do_idle+0x1be/0x4d0 kernel/sched/idle.c:332
 cpu_startup_entry+0x44/0x60 kernel/sched/idle.c:430
 start_secondary+0x101/0x110 arch/x86/kernel/smpboot.c:312
 common_startup_64+0x13e/0x147
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/01/07 05:04 linux-next 6cd6c1203113 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: rcu detected stall in loop_process_work
2025/12/31 20:03 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 loop_process_work
* Struck through repros no longer work on HEAD.