INFO: rcu detected stall in task_mm_cid_work

Status: upstream: reported C repro on 2025/12/19 20:11
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+df63b3cfac01eabd92ee@syzkaller.appspotmail.com
First crash: 224d, last: 23d
▶ ▼ Bug presence (2)
Date Name Commit Repro Result
2025/12/21 linux-6.6.y (ToT) 5fa4793a2d2d C [report] INFO: rcu detected stall in smp_call_function
2025/12/21 upstream (ToT) 9094662f6707 C Didn't crash
▶ ▼ Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in task_mm_cid_work (3) prio:low kernel 1 syz done error 2 230d 350d 0/29 upstream: reported syz repro on 2025/08/15 23:05
upstream INFO: rcu detected stall in task_mm_cid_work kernel 1 1 798d 798d 0/29 auto-obsoleted due to no activity on 2024/08/23 05:45
upstream INFO: rcu detected stall in task_mm_cid_work (2) kernel 1 12 514d 651d 0/29 auto-obsoleted due to no activity on 2025/06/03 14:36
▶ ▼ Fix bisection attempts (3)
Created Duration User Patch Repo Result
2026/03/23 22:25 1m fix candidate upstream error job log
2026/02/21 05:06 5m fix candidate upstream error job log
2026/01/21 13:25 6m fix candidate upstream error job log

Sample crash report:
rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	1-....: (7636 ticks this GP) idle=8ccc/1/0x4000000000000000 softirq=12954/12965 fqs=5247
rcu: 	         hardirqs   softirqs   csw/system
rcu: 	 number:  1528861         62            0
rcu: 	cputime:    16126      36353           37   ==> 52500(ms)
rcu: 	(t=10502 jiffies g=9473 q=2211 ncpus=2)
CPU: 1 PID: 5989 Comm: syz.1.18 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:check_kcov_mode kernel/kcov.c:182 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x27/0x60 kernel/kcov.c:216
Code: cc cc cc f3 0f 1e fa 48 8b 04 24 65 48 8b 0d f0 24 7e 7e 65 8b 15 f1 24 7e 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
RSP: 0018:ffffc900001ef9d0 EFLAGS: 00000246
RAX: ffffffff813aa367 RBX: ffffc900001efb60 RCX: ffff88801f3c3c00
RDX: 0000000000000100 RSI: ffffffff81e6251d RDI: ffffc900001efaa8
RBP: ffffc900001efb30 R08: ffffc900001efb70 R09: 0000000000000000
R10: 0000000000000004 R11: 0000000000000100 R12: ffffc900001efaa8
R13: dffffc0000000000 R14: ffffffff81746d20 R15: ffffc900001efaa8
FS:  0000555592ce6500(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055c9685d3468 CR3: 00000000731b3000 CR4: 00000000003506e0
Call Trace:
 <IRQ>
 unwind_next_frame+0x27/0x2970 arch/x86/kernel/unwind_orc.c:469
 arch_stack_walk+0x144/0x190 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122
 save_stack+0xf7/0x1f0 mm/page_owner.c:128
 __set_page_owner+0x1d/0x60 mm/page_owner.c:192
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x1cd/0x210 mm/page_alloc.c:1554
 prep_new_page mm/page_alloc.c:1561 [inline]
 get_page_from_freelist+0x195c/0x19f0 mm/page_alloc.c:3191
 __alloc_pages+0x1e3/0x460 mm/page_alloc.c:4457
 alloc_slab_page+0x5d/0x170 mm/slub.c:1881
 allocate_slab mm/slub.c:2028 [inline]
 new_slab+0x87/0x2e0 mm/slub.c:2081
 ___slab_alloc+0xc6d/0x1300 mm/slub.c:3253
 __slab_alloc mm/slub.c:3339 [inline]
 __slab_alloc_node mm/slub.c:3392 [inline]
 slab_alloc_node mm/slub.c:3485 [inline]
 slab_alloc mm/slub.c:3503 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3510 [inline]
 kmem_cache_alloc+0x1b7/0x2e0 mm/slub.c:3519
 skb_clone+0x1eb/0x370 net/core/skbuff.c:1915
 deliver_clone net/bridge/br_forward.c:125 [inline]
 maybe_deliver+0x98/0x150 net/bridge/br_forward.c:191
 br_flood+0x31b/0x680 net/bridge/br_forward.c:237
 br_dev_xmit+0x1176/0x17f0 net/bridge/br_device.c:106
 __netdev_start_xmit include/linux/netdevice.h:4943 [inline]
 netdev_start_xmit include/linux/netdevice.h:4957 [inline]
 xmit_one net/core/dev.c:3619 [inline]
 dev_hard_start_xmit+0x246/0x740 net/core/dev.c:3635
 __dev_queue_xmit+0x1a64/0x35a0 net/core/dev.c:4425
 dev_queue_xmit include/linux/netdevice.h:3113 [inline]
 neigh_hh_output include/net/neighbour.h:527 [inline]
 neigh_output include/net/neighbour.h:541 [inline]
 ip6_finish_output2+0xdf5/0x1650 net/ipv6/ip6_output.c:141
 dst_output include/net/dst.h:467 [inline]
 NF_HOOK include/linux/netfilter.h:304 [inline]
 ndisc_send_skb+0xbed/0x14b0 net/ipv6/ndisc.c:513
 addrconf_rs_timer+0x2bc/0x600 net/ipv6/addrconf.c:4006
 call_timer_fn+0x16e/0x530 kernel/time/timer.c:1701
 expire_timers kernel/time/timer.c:1752 [inline]
 __run_timers+0x52d/0x7d0 kernel/time/timer.c:2023
 run_timer_softirq+0x67/0xf0 kernel/time/timer.c:2036
 handle_softirqs+0x280/0x820 kernel/softirq.c:578
 __do_softirq kernel/softirq.c:612 [inline]
 invoke_softirq kernel/softirq.c:452 [inline]
 __irq_exit_rcu+0xc7/0x190 kernel/softirq.c:661
 irq_exit_rcu+0x9/0x20 kernel/softirq.c:673
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline]
 sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1088
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:preempt_schedule_irq+0xb0/0x140 kernel/sched/core.c:7009
Code: 44 24 20 f6 44 24 21 02 74 0b 0f 0b 48 f7 03 08 00 00 00 74 63 bf 01 00 00 00 e8 8b b3 eb f6 e8 26 3a 1c f7 fb bf 01 00 00 00 <e8> db b5 ff ff 48 c7 44 24 40 00 00 00 00 9c 8f 44 24 40 8b 44 24
RSP: 0018:ffffc90003517840 EFLAGS: 00000286
RAX: 763624262c051a00 RBX: 0000000000000000 RCX: 763624262c051a00
RDX: dffffc0000000000 RSI: ffffffff8aaabce0 RDI: 0000000000000001
RBP: ffffc900035178e0 R08: ffffffff8e4a212f R09: 1ffffffff1c94425
R10: dffffc0000000000 R11: fffffbfff1c94426 R12: 0000000000000000
R13: 0000000000000000 R14: dffffc0000000000 R15: 1ffff920006a2f08
 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:lock_acquire+0x1f2/0x410 kernel/locking/lockdep.c:5758
Code: 00 9c 8f 84 24 80 00 00 00 f6 84 24 81 00 00 00 02 0f 85 f5 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 04 3c 00 00 00 00 66 43 c7 44 3c 09 00 00 43 c6 44 3c 0b 00
RSP: 0018:ffffc900035179a0 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 763624262c051a00
RDX: 0000000000000000 RSI: ffffffff8aaace60 RDI: ffffffff8afc6f80
RBP: ffffc90003517aa8 R08: dffffc0000000000 R09: 1ffffffff21b28a0
R10: dffffc0000000000 R11: fffffbfff21b28a1 R12: 1ffff920006a2f40
R13: ffffffff8cd2ff20 R14: 0000000000000246 R15: dffffc0000000000
 rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
 rcu_read_lock include/linux/rcupdate.h:786 [inline]
 sched_mm_cid_remote_clear_old kernel/sched/core.c:11933 [inline]
 task_mm_cid_work+0x335/0x760 kernel/sched/core.c:11994
 task_work_run+0x1ce/0x250 kernel/task_work.c:239
 get_signal+0x1235/0x1400 kernel/signal.c:2678
 arch_do_signal_or_restart+0x9c/0x7b0 arch/x86/kernel/signal.c:310
 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
 exit_to_user_mode_prepare+0xf6/0x180 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:87
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f6f0138f749
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fffeb0bc8a8 EFLAGS: 00000246 ORIG_RAX: 000000000000012a
RAX: 0000000000000004 RBX: 00007f6f015e5fa0 RCX: 00007f6f0138f749
RDX: ffffffffffffffff RSI: 0000000000000000 RDI: 0000200000000140
RBP: 00007f6f01413f91 R08: 0000000000000002 R09: 0000000000000000
R10: ffffffffffffffff R11: 0000000000000246 R12: 0000000000000000
R13: 00007f6f015e5fa0 R14: 00007f6f015e5fa0 R15: 0000000000000005
 </TASK>

Crashes (10):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/12/19 20:11 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: rcu detected stall in task_mm_cid_work
2026/07/09 08:15 linux-6.6.y da47cbc25466 b9f1ceaa .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: rcu detected stall in task_mm_cid_work
2026/06/14 16:20 linux-6.6.y 924b4a879cbb 1d2f3589 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: rcu detected stall in task_mm_cid_work
2026/06/08 12:47 linux-6.6.y 924b4a879cbb cc095639 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: rcu detected stall in task_mm_cid_work
2026/06/05 21:49 linux-6.6.y 924b4a879cbb 48b6c3fa .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: rcu detected stall in task_mm_cid_work
2026/05/05 01:48 linux-6.6.y 258cf62a6dfd a898ba9c .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: rcu detected stall in task_mm_cid_work
2026/04/20 11:40 linux-6.6.y 9760bf04666d 303e2802 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: rcu detected stall in task_mm_cid_work
2026/02/26 05:50 linux-6.6.y 7a137e9bfa0e e0f78d93 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: rcu detected stall in task_mm_cid_work
2026/01/25 01:37 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 task_mm_cid_work
2026/01/03 19:37 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 task_mm_cid_work
* Struck through repros no longer work on HEAD.