INFO: rcu detected stall in ppp_ioctl (2)

Status: auto-obsoleted due to no activity on 2026/11/12 09:51
Subsystems: bpf kernfs
Labels: prio:normal
[Documentation on labels]
First crash: 94d, last: 91d
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ID Workflow Result Correct Bug Created Started Finished Revision
1e746ffb assessment-security DenialOfService: ✅ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ✅ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ INFO: rcu detected stall in ppp_ioctl (2) 2026/08/13 00:00 2026/08/13 00:00 2026/08/13 00:56 a56bc0a5
▶ ▼ Similar bugs (10)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.6 INFO: rcu detected stall in ppp_ioctl (2) 1 1 34d 34d 0/2 upstream: reported on 2026/10/10 17:18
linux-6.1 INFO: rcu detected stall in ppp_ioctl (3) 1 1 196d 196d 0/3 auto-obsoleted due to no activity on 2026/08/09 22:48
linux-5.15 INFO: rcu detected stall in ppp_ioctl 1 1 325d 325d 0/3 auto-obsoleted due to no activity on 2026/04/02 20:21
linux-6.1 INFO: rcu detected stall in ppp_ioctl 1 1 773d 773d 0/3 auto-obsoleted due to no activity on 2025/01/09 16:14
upstream INFO: rcu detected stall in ppp_ioctl mm 1 3 731d 746d 0/29 auto-obsoleted due to no activity on 2025/02/10 18:41
linux-6.1 INFO: rcu detected stall in ppp_ioctl (2) 1 1 393d 393d 0/3 auto-obsoleted due to no activity on 2026/01/24 16:32
linux-6.6 INFO: rcu detected stall in ppp_ioctl 1 1 146d 146d 0/2 auto-obsoleted due to no activity on 2026/09/28 19:57
linux-5.15 INFO: rcu detected stall in ppp_ioctl (2) 1 2 16d 31d 0/3 upstream: reported on 2026/10/14 01:54
linux-6.1 INFO: rcu detected stall in ppp_ioctl (4) 1 2 19d 55d 0/3 upstream: reported on 2026/09/19 16:18
android-5-15 BUG: soft lockup in ppp_ioctl 1 5 811d 938d 0/2 auto-obsoleted due to no activity on 2024/11/22 22:02

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P8438/1:b..l
rcu: 	(detected by 0, t=10502 jiffies, g=50513, q=891 ncpus=1)
task:syz.8.497       state:R  running task     stack:26784 pid:8438  tgid:8419  ppid:6958   task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5510 [inline]
 __schedule+0x17d9/0x56c0 kernel/sched/core.c:7234
 preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7556
 irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:539 [inline]
 irqentry_exit+0x14f/0x8f0 kernel/entry/common.c:167
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
RIP: 0010:lock_release+0x2d7/0x3c0 kernel/locking/lockdep.c:5893
Code: 3b ca 11 00 00 00 00 eb b5 e8 b5 eb 2d 0a f7 c3 00 02 00 00 74 b9 65 48 8b 05 45 f6 c9 11 48 3b 44 24 28 75 44 fb 48 83 c4 30 <5b> 41 5c 41 5d 41 5e 41 5f 5d e9 15 57 6d ff cc 48 8d 3d c2 f3 b7
RSP: 0018:ffffc90004d07558 EFLAGS: 00000282
RAX: 76b1edda2b64c000 RBX: 0000000000000206 RCX: 0000000000000046
RDX: 0000000000000002 RSI: ffffffff8e4ae7eb RDI: ffffffff8c4bbf80
RBP: ffff888031dc68f0 R08: ffffffff81d75476 R09: 0000000000000000
R10: 0000000000000000 R11: ffffffff8eb59c60 R12: 0000000000000002
R13: 0000000000000002 R14: ffffffff8eb59c60 R15: ffff888031dc5d00
 rcu_lock_release include/linux/rcupdate.h:310 [inline]
 rcu_read_unlock include/linux/rcupdate.h:871 [inline]
 is_bpf_text_address+0x28d/0x2b0 kernel/bpf/core.c:750
 kernel_text_address+0xa5/0xe0 kernel/extable.c:125
 __kernel_text_address+0xd/0x30 kernel/extable.c:79
 unwind_get_return_address+0x4d/0x90 arch/x86/kernel/unwind_orc.c:385
 arch_stack_walk+0xfb/0x150 arch/x86/kernel/stacktrace.c:26
 stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 unpoison_slab_object mm/kasan/common.c:340 [inline]
 __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4584 [inline]
 slab_alloc_node mm/slub.c:4917 [inline]
 kmem_cache_alloc_lru_noprof+0x2aa/0x5f0 mm/slub.c:4950
 alloc_inode+0x6a/0x1b0 fs/inode.c:338
 new_inode+0x1f/0x170 fs/inode.c:1174
 debugfs_get_inode fs/debugfs/inode.c:72 [inline]
 __debugfs_create_file+0xb8/0x400 fs/debugfs/inode.c:433
 debugfs_create_file_full+0x3f/0x60 fs/debugfs/inode.c:460
 ref_tracker_dir_debugfs+0x197/0x360 lib/ref_tracker.c:440
 ref_tracker_dir_init include/linux/ref_tracker.h:70 [inline]
 alloc_netdev_mqs+0x275/0x12b0 net/core/dev.c:12066
 ppp_create_interface drivers/net/ppp/ppp_generic.c:3366 [inline]
 ppp_unattached_ioctl drivers/net/ppp/ppp_generic.c:1064 [inline]
 ppp_ioctl+0xa87/0x1c20 drivers/net/ppp/ppp_generic.c:731
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe43199e0d9
RSP: 002b:00007fe42fbd5028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fe431c26180 RCX: 00007fe43199e0d9
RDX: 0000200000000300 RSI: 00000000c004743e RDI: 000000000000000c
RBP: 00007fe431a35024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe431c26218 R14: 00007fe431c26180 R15: 00007ffd993222d8
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/14 09:46 upstream 3aa1dcaa4f6f b13552fe .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: rcu detected stall in ppp_ioctl
2026/08/11 17:53 upstream d58772d8520c 37a258dd .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: rcu detected stall in ppp_ioctl
* Struck through repros no longer work on HEAD.