INFO: rcu detected stall in kernfs_iop_get_link (3)

Status: auto-obsoleted due to no activity on 2026/09/12 12:29
Subsystems: mm
Labels: prio:high
[Documentation on labels]
First crash: 99d, last: 99d
✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision
1d7fb2a3 assessment-security DenialOfService: ✅ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ✅ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ✅ VMGuestTrigger: ❌ VMHostTrigger: ❌ INFO: rcu detected stall in kernfs_iop_get_link (3) 2026/06/16 00:01 2026/06/16 00:01 2026/06/16 00:31 50bb0618
Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 INFO: rcu detected stall in kernfs_iop_get_link origin:lts-only 1 syz, C error 1 206d 206d 0/3 upstream: reported C repro on 2026/02/27 11:59
upstream INFO: rcu detected stall in kernfs_iop_get_link mm 1 4 649d 718d 0/29 auto-obsoleted due to no activity on 2025/03/11 07:30
upstream INFO: rcu detected stall in kernfs_iop_get_link (2) kernfs 1 4 260d 307d 0/29 auto-obsoleted due to no activity on 2026/04/04 14:21

Sample crash report:
bridge0: received packet on veth1_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P16003/1:b..l P5000/1:b..l
rcu: 	(detected by 1, t=10503 jiffies, g=110633, q=1018 ncpus=2)
task:udevd           state:R  running task     stack:23400 pid:5000  tgid:5000  ppid:1      task_flags:0x400140 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5388 [inline]
 __schedule+0x1840/0x57a0 kernel/sched/core.c:7189
 preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7513
 irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:539 [inline]
 irqentry_exit+0x14f/0x8e0 kernel/entry/common.c:164
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:lock_acquire+0xe/0x350 kernel/locking/lockdep.c:5828
Code: 58 0e 04 0a cc 0f 1f 80 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 55 41 57 41 56 41 55 41 54 53 <48> 83 ec 60 4d 89 ce 45 89 c7 41 89 cc 89 54 24 04 89 f3 49 89 fd
RSP: 0018:ffffc900051cf720 EFLAGS: 00000246
RAX: 0000000000000001 RBX: ffffffff82308fd9 RCX: 0000000000000002
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8e95c780
RBP: 1ffff92000a39f08 R08: 0000000000000000 R09: 0000000000000000
R10: ffffc900051cf858 R11: ffffffff81b071b0 R12: dffffc0000000000
R13: ffffffff81769f7f R14: ffffc900051cf808 R15: 1ffff92000a39f01
 rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
 rcu_read_lock include/linux/rcupdate.h:838 [inline]
 class_rcu_constructor include/linux/rcupdate.h:1181 [inline]
 unwind_next_frame+0xac/0x2550 arch/x86/kernel/unwind_orc.c:495
 arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122
 save_stack+0x122/0x230 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:1397 [inline]
 __free_frozen_pages+0xc0d/0xd20 mm/page_alloc.c:2938
 __slab_free+0x274/0x2c0 mm/slub.c:5613
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x99/0x100 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:350
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4570 [inline]
 slab_alloc_node mm/slub.c:4899 [inline]
 __kmalloc_cache_noprof+0x2b6/0x660 mm/slub.c:5415
 kmalloc_noprof include/linux/slab.h:950 [inline]
 kzalloc_noprof include/linux/slab.h:1188 [inline]
 kernfs_iop_get_link+0x66/0x6c0 fs/kernfs/symlink.c:137
 vfs_readlink+0x24a/0x540 fs/namei.c:6275
 do_readlinkat+0x218/0x510 fs/stat.c:583
 __do_sys_readlink fs/stat.c:605 [inline]
 __se_sys_readlink fs/stat.c:602 [inline]
 __x64_sys_readlink+0x7f/0x90 fs/stat.c:602
 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: 0033:0x7f5de2f153a7
RSP: 002b:00007fff36ff2a18 EFLAGS: 00000246 ORIG_RAX: 0000000000000059
RAX: ffffffffffffffda RBX: 00007fff36ff2ef0 RCX: 00007f5de2f153a7
RDX: 0000000000000400 RSI: 00007fff36ff2a20 RDI: 00007fff36ff2ef0
RBP: 00007fff36ff2a20 R08: 0000000000000075 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000400
R13: 00005595d85c5100 R14: 0000000000000001 R15: 00007fff36ff47f0
 </TASK>
task:syz-executor    state:R  running task     stack:22088 pid:16003 tgid:16003 ppid:15993  task_flags:0x400140 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5388 [inline]
 __schedule+0x1840/0x57a0 kernel/sched/core.c:7189
 preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7513
 irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:539 [inline]
 irqentry_exit+0x14f/0x8e0 kernel/entry/common.c:164
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:unwind_next_frame+0x45e/0x2550 arch/x86/kernel/unwind_orc.c:520
Code: 5e 00 48 c7 c1 60 f4 7b 8e 31 d2 84 c0 48 0f 45 d1 48 89 15 a4 2e c6 11 48 85 d2 0f 84 2e 02 00 00 48 8d 5a 04 48 89 54 24 18 <4c> 8d 6a 05 48 89 d8 48 c1 e8 03 42 0f b6 04 20 84 c0 0f 85 b4 19
RSP: 0018:ffffc90006cbf7e0 EFLAGS: 00000282
RAX: 0000000000000000 RBX: ffffffff90d165a6 RCX: ffffffff90515924
RDX: ffffffff90d165a2 RSI: ffffffff90d165a2 RDI: ffffffff8c289940
RBP: ffffffff82308ea7 R08: 0000000000000007 R09: 0000000000000000
R10: 0000000000000000 R11: ffffffff8e95c780 R12: dffffc0000000000
R13: 0000000000000000 R14: ffffc90006cbf888 R15: ffffffff90515924
 arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122
 save_stack+0x122/0x230 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:1397 [inline]
 __free_frozen_pages+0xc0d/0xd20 mm/page_alloc.c:2938
 __slab_free+0x274/0x2c0 mm/slub.c:5613
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x99/0x100 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:350
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4570 [inline]
 slab_alloc_node mm/slub.c:4899 [inline]
 kmem_cache_alloc_noprof+0x2b8/0x650 mm/slub.c:4906
 lsm_inode_alloc security/security.c:254 [inline]
 security_inode_alloc+0x39/0x310 security/security.c:1215
 inode_init_always_gfp+0x97e/0xd30 fs/inode.c:305
 inode_init_always include/linux/fs.h:2936 [inline]
 alloc_inode+0x82/0x1b0 fs/inode.c:352
 new_inode_pseudo include/linux/fs.h:3015 [inline]
 sock_alloc net/socket.c:697 [inline]
 __sock_create+0x12d/0x9d0 net/socket.c:1629
 sock_create net/socket.c:1723 [inline]
 __sys_socket_create net/socket.c:1760 [inline]
 __sys_socket+0xd6/0x1b0 net/socket.c:1807
 __do_sys_socket net/socket.c:1821 [inline]
 __se_sys_socket net/socket.c:1819 [inline]
 __x64_sys_socket+0x7a/0x90 net/socket.c:1819
 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: 0033:0x7fcfb899e6c7
RSP: 002b:00007ffefdbb9a68 EFLAGS: 00000202 ORIG_RAX: 0000000000000029
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007fcfb899e6c7
RDX: 0000000000000006 RSI: 0000000000000001 RDI: 0000000000000002
RBP: 00007ffefdbba19c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 00007fcfb8beafc0
R13: 0000000000000063 R14: 000000000008b8f4 R15: 00007fcfb8bed180
 </TASK>
net_ratelimit: 15186 callbacks suppressed
bridge0: received packet on veth1_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_1 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth1_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_1 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_1 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth1_to_bridge with own address as source address (addr:06:a4:78:66:2c:b4, vlan:0)
net_ratelimit: 17145 callbacks suppressed
bridge0: received packet on veth1_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_1 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth1_to_bridge with own address as source address (addr:06:a4:78:66:2c:b4, vlan:0)
bridge0: received packet on bridge_slave_1 with own address as source address (addr:aa:aa:aa:aa:aa:1c, vlan:0)
bridge0: received packet on veth1_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_1 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/06/14 12:19 net a4004aa0debf 1d2f3589 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce INFO: rcu detected stall in kernfs_iop_get_link
* Struck through repros no longer work on HEAD.