INFO: rcu detected stall in prctl (3)

Status: auto-obsoleted due to no activity on 2026/10/10 16:43
Subsystems: kernel
Labels: prio:high
[Documentation on labels]
First crash: 91d, last: 91d
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ID Workflow Result Correct Bug Created Started Finished Revision
80653b77 assessment-security DenialOfService: ✅ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ✅ UserNamespace: ✅ VMGuestTrigger: ✅ VMHostTrigger: ❌ ❓ INFO: rcu detected stall in prctl (3) 2026/07/14 00:00 2026/07/14 00:00 2026/07/14 00:55 2130f682
▶ ▼ Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.6 INFO: rcu detected stall in prctl 1 1 102d 102d 0/2 auto-obsoleted due to no activity on 2026/10/09 20:59
upstream INFO: rcu detected stall in prctl (2) modules 1 1 535d 535d 0/29 auto-obsoleted due to no activity on 2025/07/23 15:29
upstream INFO: rcu detected stall in prctl kernel 1 1 644d 644d 0/29 auto-obsoleted due to no activity on 2025/04/06 07:13

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-...!: (1 GPs behind) idle=c094/1/0x4000000000000000 softirq=71806/71807 fqs=21
rcu: 	(detected by 1, t=10506 jiffies, g=85681, q=384 ncpus=2)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 14812 Comm: syz.6.2315 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/10/2026
RIP: 0010:find_held_lock+0x0/0x80 kernel/locking/lockdep.c:5343
Code: 91 89 c2 48 c7 c6 c2 3b 06 91 48 c7 c7 03 d5 17 8e e9 e4 4e 3d ff 0f 1f 40 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 <41> 56 41 89 d6 41 55 49 89 cd 41 54 49 89 f4 55 8d 6a ff 48 63 c5
RSP: 0018:ffffc90000007e30 EFLAGS: 00000006
RAX: 0000000000000000 RBX: ffff8880b8428418 RCX: ffffc90000007e44
RDX: 0000000000000005 RSI: ffff8880b8428418 RDI: ffff888032f20000
RBP: ffffffff81f5913b R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff888032f20000
R13: ffffffff89c6f9a0 R14: 0000000000000083 R15: 0000000000000005
FS:  00007f21e36ae6c0(0000) GS:ffff888123deb000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fde06391ff8 CR3: 000000002333a000 CR4: 00000000003526f0
Call Trace:
 <IRQ>
 __lock_release kernel/locking/lockdep.c:5535 [inline]
 lock_release kernel/locking/lockdep.c:5889 [inline]
 lock_release+0xdb/0x310 kernel/locking/lockdep.c:5875
 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:176 [inline]
 _raw_spin_unlock_irqrestore+0x1a/0x80 kernel/locking/spinlock.c:198
 __run_hrtimer kernel/time/hrtimer.c:2028 [inline]
 __hrtimer_run_queues+0x37b/0x9c0 kernel/time/hrtimer.c:2096
 hrtimer_interrupt+0x3e5/0x940 kernel/time/hrtimer.c:2215
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1051 [inline]
 __sysvec_apic_timer_interrupt+0x109/0x470 arch/x86/kernel/apic/apic.c:1068
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline]
 sysvec_apic_timer_interrupt+0x9e/0xc0 arch/x86/kernel/apic/apic.c:1062
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
RIP: 0010:lock_is_held_type+0xf5/0x140 kernel/locking/lockdep.c:5945
Code: ff ff ff ff 65 0f c1 15 19 65 aa 08 83 fa 01 8b 44 24 04 75 2d 9c 5a 80 e6 02 75 47 41 f7 c5 00 02 00 00 74 01 fb 48 83 c4 08 <5b> 5d 41 5c 41 5d 41 5e 41 5f e9 7c 3f 03 00 c3 cc cc cc cc 31 c0
RSP: 0018:ffffc90005277bb0 EFLAGS: 00000292
RAX: 0000000000000001 RBX: ffffffff8ea97840 RCX: 0000000000000001
RDX: 0000000000000046 RSI: ffffffff8e17d521 RDI: ffffffff8c400f80
RBP: ffff888032f20000 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: 00000000ffffffff
R13: 0000000000000246 R14: ffff888032f20c18 R15: 0000000000000003
 lock_is_held include/linux/lockdep.h:249 [inline]
 text_poke+0x8e/0xc0 arch/x86/kernel/alternative.c:2670
 smp_text_poke_batch_finish+0x6b5/0xc60 arch/x86/kernel/alternative.c:3061
 arch_jump_label_transform_apply+0x1c/0x30 arch/x86/kernel/jump_label.c:146
 jump_label_update+0x37a/0x550 kernel/jump_label.c:910
 static_key_enable_cpuslocked+0x1bc/0x270 kernel/jump_label.c:210
 static_key_enable+0x1a/0x20 kernel/jump_label.c:223
 __sched_core_enable kernel/sched/core.c:475 [inline]
 sched_core_get+0x8a/0xa0 kernel/sched/core.c:499
 sched_core_alloc_cookie kernel/sched/core_sched.c:20 [inline]
 sched_core_share_pid+0x406/0x9d0 kernel/sched/core_sched.c:187
 __do_sys_prctl+0x67b/0x2270 kernel/sys.c:2808
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f21e279de59
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:00007f21e36ae028 EFLAGS: 00000246 ORIG_RAX: 000000000000009d
RAX: ffffffffffffffda RBX: 00007f21e2a25fa0 RCX: 00007f21e279de59
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 000000000000003e
RBP: 00007f21e2833e6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000002 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f21e2a26038 R14: 00007f21e2a25fa0 R15: 00007ffcfff2a948
 </TASK>
rcu: rcu_preempt kthread starved for 10300 jiffies! g85681 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:27528 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5510 [inline]
 __schedule+0x125c/0x6730 kernel/sched/core.c:7234
 __schedule_loop kernel/sched/core.c:7311 [inline]
 schedule+0xdd/0x2c0 kernel/sched/core.c:7326
 schedule_timeout+0x127/0x280 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x1a9/0x900 kernel/rcu/tree.c:2123
 rcu_gp_kthread+0x179/0x230 kernel/rcu/tree.c:2325
 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: 1 UID: 0 PID: 13214 Comm: kworker/u8:21 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/10/2026
Workqueue: writeback wb_workfn (flush-8:0)
RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline]
RIP: 0010:smp_call_function_many_cond+0x589/0x16c0 kernel/smp.c:892
Code: b8 00 00 00 00 00 fc ff df 48 8b 54 24 08 49 89 d5 49 89 d4 49 c1 ed 03 41 83 e4 07 49 01 c5 41 83 c4 03 e8 c9 95 0c 00 f3 90 <41> 0f b6 45 00 41 38 c4 7c 08 84 c0 0f 85 2c 0f 00 00 8b 45 08 31
RSP: 0018:ffffc90004d66820 EFLAGS: 00000293
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff81fd45bd
RDX: ffff8880292b8000 RSI: ffffffff81fd4597 RDI: ffff8880292b8000
RBP: ffff8880b8443680 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000003
R13: ffffed10170886d1 R14: 0000000000000001 R15: ffff8880b853c880
FS:  0000000000000000(0000) GS:ffff888123eeb000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2f00cff8 CR3: 000000008129d000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 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
 flush_tlb_page arch/x86/include/asm/tlbflush.h:345 [inline]
 ptep_clear_flush+0x148/0x170 mm/pgtable-generic.c:104
 page_vma_mkclean_one.constprop.0+0x3a2/0x7b0 mm/rmap.c:1138
 page_mkclean_one+0x1cd/0x2b0 mm/rmap.c:1186
 __rmap_walk_file+0x383/0x680 mm/rmap.c:3064
 rmap_walk_file+0x1d8/0x2a0 mm/rmap.c:3097
 rmap_walk mm/rmap.c:3108 [inline]
 folio_mkclean+0x2af/0x4e0 mm/rmap.c:1218
 folio_clear_dirty_for_io+0x1ba/0x960 mm/page-writeback.c:2909
 mpage_submit_folio+0x84/0x330 fs/ext4/inode.c:2085
 mpage_process_page_bufs+0x473/0x8d0 fs/ext4/inode.c:2215
 mpage_prepare_extent_to_map+0xb50/0x1920 fs/ext4/inode.c:2754
 ext4_do_writepages+0x9f9/0x3ed0 fs/ext4/inode.c:2895
 ext4_writepages+0x347/0x750 fs/ext4/inode.c:3043
 do_writepages+0x278/0x600 mm/page-writeback.c:2571
 __writeback_single_inode+0x164/0x1300 fs/fs-writeback.c:1787
 writeback_sb_inodes+0x766/0x1c50 fs/fs-writeback.c:2079
 __writeback_inodes_wb+0xf8/0x2d0 fs/fs-writeback.c:2155
 wb_writeback+0x6f6/0xb50 fs/fs-writeback.c:2266
 wb_check_old_data_flush fs/fs-writeback.c:2370 [inline]
 wb_do_writeback fs/fs-writeback.c:2449 [inline]
 wb_workfn+0x93f/0xc80 fs/fs-writeback.c:2477
 process_one_work+0xa23/0x1940 kernel/workqueue.c:3322
 process_scheduled_works kernel/workqueue.c:3405 [inline]
 worker_thread+0x5ef/0xe50 kernel/workqueue.c:3486
 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>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/07/12 16:32 upstream 44696aa3a489 d78ea535 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: rcu detected stall in prctl
* Struck through repros no longer work on HEAD.