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INFO: rcu detected stall in sys_symlink

Status: upstream: reported on 2025/06/29 08:06
Reported-by: syzbot+ab9e06718428c4f9e7c8@syzkaller.appspotmail.com
First crash: 79d, last: 79d
▶ ▼ Similar bugs (5)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in sys_symlink (3) mm 1 4 2078d 2078d 0/29 closed as invalid on 2020/01/09 08:13
upstream INFO: rcu detected stall in sys_symlink (2) mm cgroups 1 2 2078d 2078d 0/29 closed as invalid on 2020/01/08 05:23
upstream INFO: rcu detected stall in sys_symlink mm 1 17 2113d 2115d 0/29 closed as invalid on 2019/12/04 14:14
upstream INFO: rcu detected stall in sys_symlink (4) bpf 1 11 1341d 1446d 0/29 closed as invalid on 2022/02/08 09:50
upstream INFO: rcu detected stall in sys_symlink (5) mm fs 1 syz inconclusive done 6 290d 340d 0/29 closed as invalid on 2025/02/03 10:48

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P54/1:b..l P5925/1:b..l
rcu: 	(detected by 0, t=10502 jiffies, g=32933, q=341 ncpus=2)
task:udevd           state:R  running task     stack:24776 pid:5925  ppid:5142   flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x14e2/0x4580 kernel/sched/core.c:6700
 preempt_schedule_irq+0xb5/0x140 kernel/sched/core.c:7010
 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:ffffc90004eaf660 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 9f704a5bdde76e00
RDX: 0000000000000000 RSI: ffffffff8aaac440 RDI: ffffffff8afc6ac0
RBP: ffffc90004eaf770 R08: dffffc0000000000 R09: 1ffffffff21b0aa4
R10: dffffc0000000000 R11: fffffbfff21b0aa5 R12: 1ffff920009d5ed8
R13: ffffffff8cd2f760 R14: 0000000000000246 R15: dffffc0000000000
 rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
 rcu_read_lock include/linux/rcupdate.h:786 [inline]
 is_bpf_text_address+0x47/0x2a0 kernel/bpf/core.c:741
 kernel_text_address+0xa0/0xd0 kernel/extable.c:125
 __kernel_text_address+0xd/0x30 kernel/extable.c:79
 unwind_get_return_address+0x5d/0xc0 arch/x86/kernel/unwind_orc.c:369
 arch_stack_walk+0x11d/0x190 arch/x86/kernel/stacktrace.c:26
 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4e/0x70 mm/kasan/common.c:52
 __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:328
 kasan_slab_alloc include/linux/kasan.h:188 [inline]
 slab_post_alloc_hook+0x6e/0x4d0 mm/slab.h:767
 slab_alloc_node mm/slub.c:3485 [inline]
 slab_alloc mm/slub.c:3493 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3500 [inline]
 kmem_cache_alloc_lru+0x115/0x2e0 mm/slub.c:3516
 __d_alloc+0x31/0x730 fs/dcache.c:1773
 d_alloc+0x4b/0x1b0 fs/dcache.c:1853
 lookup_one_qstr_excl+0xca/0x250 fs/namei.c:1605
 filename_create+0x222/0x460 fs/namei.c:3883
 do_symlinkat+0xbd/0x3f0 fs/namei.c:4492
 __do_sys_symlink fs/namei.c:4520 [inline]
 __se_sys_symlink fs/namei.c:4518 [inline]
 __x64_sys_symlink+0x7e/0x90 fs/namei.c:4518
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7feb73b15527
RSP: 002b:00007fff64af2278 EFLAGS: 00000202 ORIG_RAX: 0000000000000058
RAX: ffffffffffffffda RBX: 0000559e2f2fa950 RCX: 00007feb73b15527
RDX: 0000000000000000 RSI: 0000559e2f2fa950 RDI: 00007fff64af2330
RBP: 0000559e2f2fa96c R08: 0000559e2f2f2800 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 00007fff64af33c5
R13: 00007fff64af2330 R14: 0000559e17d596d7 R15: 00007fff64af33c0
 </TASK>
task:kworker/u4:4    state:R  running task     stack:22320 pid:54    ppid:2      flags:0x00004000
Workqueue: bat_events batadv_iv_send_outstanding_bat_ogm_packet
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x14e2/0x4580 kernel/sched/core.c:6700
 preempt_schedule_irq+0xb5/0x140 kernel/sched/core.c:7010
 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:ffffc90000bf78a0 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 8d52600673d49c00
RDX: 0000000000000000 RSI: ffffffff8aaac440 RDI: ffffffff8afc6ac0
RBP: ffffc90000bf79a8 R08: dffffc0000000000 R09: 1ffffffff21b0aa4
R10: dffffc0000000000 R11: fffffbfff21b0aa5 R12: 1ffff9200017ef20
R13: ffffffff8cd2f760 R14: 0000000000000246 R15: dffffc0000000000
 rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
 rcu_read_lock include/linux/rcupdate.h:786 [inline]
 batadv_iv_ogm_slide_own_bcast_window net/batman-adv/bat_iv_ogm.c:753 [inline]
 batadv_iv_ogm_schedule_buff net/batman-adv/bat_iv_ogm.c:824 [inline]
 batadv_iv_ogm_schedule+0x417/0xe90 net/batman-adv/bat_iv_ogm.c:867
 batadv_iv_send_outstanding_bat_ogm_packet+0x731/0x840 net/batman-adv/bat_iv_ogm.c:1711
 process_one_work kernel/workqueue.c:2634 [inline]
 process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711
 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>
rcu: rcu_preempt kthread starved for 10576 jiffies! g32933 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
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:26920 pid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x14e2/0x4580 kernel/sched/core.c:6700
 schedule+0xbd/0x170 kernel/sched/core.c:6774
 schedule_timeout+0x160/0x280 kernel/time/timer.c:2167
 rcu_gp_fqs_loop+0x302/0x1560 kernel/rcu/tree.c:1667
 rcu_gp_kthread+0x99/0x380 kernel/rcu/tree.c:1866
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 6.6.95-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:pv_native_safe_halt+0x13/0x20 arch/x86/kernel/paravirt.c:148
Code: cc cc cc cc cc cc cc f3 0f 1e fa 0f 0b 66 2e 0f 1f 84 00 00 00 00 00 f3 0f 1e fa 66 90 0f 00 2d c3 bf 41 00 f3 0f 1e fa fb f4 <c3> cc cc cc cc cc cc cc cc cc cc cc cc 66 0f 1f 00 55 41 57 41 56
RSP: 0018:ffffffff8ca07d80 EFLAGS: 000002c2
RAX: f4bea2910049c800 RBX: ffffffff81618a7b RCX: f4bea2910049c800
RDX: 0000000000000001 RSI: ffffffff8aaab2c0 RDI: ffffffff8afc6ac0
RBP: ffffffff8ca07eb8 R08: ffff8880b8e36d4b R09: 1ffff110171c6da9
R10: dffffc0000000000 R11: ffffed10171c6daa R12: ffffffff8e49ac28
R13: 0000000000000000 R14: 0000000000000000 R15: 1ffffffff1952670
FS:  0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f35c5592feb CR3: 0000000024d93000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 arch_safe_halt arch/x86/include/asm/paravirt.h:108 [inline]
 default_idle+0x13/0x20 arch/x86/kernel/process.c:753
 default_idle_call+0x6c/0xa0 kernel/sched/idle.c:97
 cpuidle_idle_call kernel/sched/idle.c:170 [inline]
 do_idle+0x1eb/0x510 kernel/sched/idle.c:282
 cpu_startup_entry+0x43/0x60 kernel/sched/idle.c:380
 rest_init+0x2e2/0x300 init/main.c:732
 arch_call_rest_init+0xe/0x10 init/main.c:829
 start_kernel+0x459/0x4e0 init/main.c:1074
 x86_64_start_reservations+0x2a/0x30 arch/x86/kernel/head64.c:555
 x86_64_start_kernel+0x60/0x60 arch/x86/kernel/head64.c:536
 secondary_startup_64_no_verify+0x179/0x17b
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/06/29 08:06 linux-6.6.y 3f5b4c104b7d fc9d8ee5 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in sys_symlink
* Struck through repros no longer work on HEAD.