INFO: rcu detected stall in dentry_kill

Status: upstream: reported on 2026/02/01 10:07
Reported-by: syzbot+40ef4113d0cb4e05dc9b@syzkaller.appspotmail.com
First crash: 198d, last: 20d
▶ ▼ Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in dentry_kill prio:high mm 1 syz, C error 51 2d14h 59d 0/29 upstream: reported C repro on 2026/06/20 03:58
linux-5.15 INFO: rcu detected stall in dentry_kill origin:lts-only 1 syz, C 8 16d 104d 0/3 upstream: reported C repro on 2026/05/06 04:01
linux-6.1 INFO: rcu detected stall in dentry_kill 1 14 8d09h 210d 0/3 upstream: reported on 2026/01/20 19:30

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P5140/1:b..l P7621/1:b..l P7655/1:b..l
rcu: 	(detected by 1, t=10504 jiffies, g=19873, q=94 ncpus=2)
task:syz.4.337       state:R  running task     stack:25192 pid:7655  ppid:6905   flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x15ae/0x4660 kernel/sched/core.c:6701
 preempt_schedule_common+0x82/0xc0 kernel/sched/core.c:6868
 preempt_schedule+0xc0/0xd0 kernel/sched/core.c:6892
 preempt_schedule_thunk+0x1a/0x30 arch/x86/entry/thunk_64.S:45
 unwind_next_frame+0x201c/0x2990 arch/x86/kernel/unwind_orc.c:672
 arch_stack_walk+0x144/0x190 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0xaa/0x100 kernel/stacktrace.c:122
 save_stack+0x125/0x230 mm/page_owner.c:128
 __reset_page_owner+0x4e/0x190 mm/page_owner.c:149
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1182 [inline]
 free_unref_page_prepare+0x7d7/0x8f0 mm/page_alloc.c:2366
 free_unref_page_list+0xbe/0x860 mm/page_alloc.c:2505
 release_pages+0x208a/0x2300 mm/swap.c:1022
 __folio_batch_release+0x71/0xe0 mm/swap.c:1042
 folio_batch_release include/linux/pagevec.h:83 [inline]
 shmem_undo_range+0x5ff/0x1a80 mm/shmem.c:1026
 shmem_truncate_range mm/shmem.c:1135 [inline]
 shmem_evict_inode+0x285/0xa70 mm/shmem.c:1264
 evict+0x4b7/0x8a0 fs/inode.c:705
 __dentry_kill+0x412/0x630 fs/dcache.c:611
 dentry_kill+0xb8/0x290 fs/dcache.c:-1
 dput+0xfe/0x1e0 fs/dcache.c:918
 __fput+0x5b2/0x940 fs/file_table.c:426
 task_work_run+0x1d4/0x260 kernel/task_work.c:245
 exit_task_work include/linux/task_work.h:43 [inline]
 do_exit+0x986/0x2530 kernel/exit.c:884
 do_group_exit+0x22d/0x2f0 kernel/exit.c:1026
 get_signal+0x12a6/0x1390 kernel/signal.c:2903
 arch_do_signal_or_restart+0xc2/0x7b0 arch/x86/kernel/signal.c:310
 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
 exit_to_user_mode_prepare+0xee/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:82
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f972839de99
RSP: 002b:00007f97292c9028 EFLAGS: 00000246 ORIG_RAX: 000000000000012b
RAX: 0000000000010106 RBX: 00007f9728626090 RCX: 00007f972839de99
RDX: 0000000000010106 RSI: 00002000000000c0 RDI: 0000000000000003
RBP: 00007f9728433eaf R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000002 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f9728626128 R14: 00007f9728626090 R15: 00007ffc63795c48
 </TASK>
task:syz.0.333       state:R  running task     stack:22760 pid:7621  ppid:5770   flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x15ae/0x4660 kernel/sched/core.c:6701
 preempt_schedule_irq+0xbf/0x150 kernel/sched/core.c:7011
 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+0x208/0x420 kernel/locking/lockdep.c:5758
Code: f7 84 24 80 00 00 00 00 02 00 00 43 c6 44 3c 04 f8 0f 85 f0 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 43 c7 44 3c 08 00 00 00 00 65 48 8b 04 25
RSP: 0018:ffffc90004d4f040 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 0c53b81de13a5800
RDX: 0000000000000000 RSI: ffffffff8acadd60 RDI: ffffffff8b1d0660
RBP: ffffc90004d4f150 R08: dffffc0000000000 R09: 1ffffffff223d6a0
R10: dffffc0000000000 R11: fffffbfff223d6a1 R12: 1ffff920009a9e14
R13: ffffffff8d131da0 R14: 0000000000000246 R15: dffffc0000000000
 rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
 rcu_read_lock include/linux/rcupdate.h:786 [inline]
 page_ext_get+0x3e/0x2b0 mm/page_ext.c:508
 __reset_page_owner+0x2e/0x190 mm/page_owner.c:145
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1182 [inline]
 free_unref_page_prepare+0x7d7/0x8f0 mm/page_alloc.c:2366
 free_unref_page_list+0xbe/0x860 mm/page_alloc.c:2505
 release_pages+0x208a/0x2300 mm/swap.c:1022
 __folio_batch_release+0x71/0xe0 mm/swap.c:1042
 folio_batch_release include/linux/pagevec.h:83 [inline]
 shmem_undo_range+0x5ff/0x1a80 mm/shmem.c:1026
 shmem_truncate_range mm/shmem.c:1135 [inline]
 shmem_evict_inode+0x285/0xa70 mm/shmem.c:1264
 evict+0x4b7/0x8a0 fs/inode.c:705
 __dentry_kill+0x412/0x630 fs/dcache.c:611
 dentry_kill+0xb8/0x290 fs/dcache.c:-1
 dput+0xfe/0x1e0 fs/dcache.c:918
 __fput+0x5b2/0x940 fs/file_table.c:426
 task_work_run+0x1d4/0x260 kernel/task_work.c:245
 exit_task_work include/linux/task_work.h:43 [inline]
 do_exit+0x986/0x2530 kernel/exit.c:884
 do_group_exit+0x22d/0x2f0 kernel/exit.c:1026
 get_signal+0x12a6/0x1390 kernel/signal.c:2903
 arch_do_signal_or_restart+0xc2/0x7b0 arch/x86/kernel/signal.c:310
 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
 irqentry_exit_to_user_mode+0x9/0x30 kernel/entry/common.c:315
 exc_page_fault+0x8c/0x100 arch/x86/mm/fault.c:1519
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:608
RIP: 0033:0x7f60ea99dea1
RSP: 002b:fffffffffffffe70 EFLAGS: 00010217
RAX: 0000000000000000 RBX: 00007f60eac26090 RCX: 00007f60ea99de99
RDX: 0000000000000000 RSI: fffffffffffffe70 RDI: 0000000000008000
RBP: 00007f60eaa33eaf R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 00007f60eac26128 R14: 00007f60eac26090 R15: 00007fffdfe59a28
 </TASK>
task:udevd           state:R  running task     stack:23176 pid:5140  ppid:1      flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x15ae/0x4660 kernel/sched/core.c:6701
 preempt_schedule_common+0x82/0xc0 kernel/sched/core.c:6868
 preempt_schedule+0xc0/0xd0 kernel/sched/core.c:6892
 preempt_schedule_thunk+0x1a/0x30 arch/x86/entry/thunk_64.S:45
 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
 _raw_spin_unlock_irqrestore+0x111/0x120 kernel/locking/spinlock.c:194
 spin_unlock_irqrestore include/linux/spinlock.h:406 [inline]
 __wake_up_common_lock kernel/sched/wait.c:140 [inline]
 __wake_up_sync_key+0x12c/0x1a0 kernel/sched/wait.c:213
 sock_def_readable+0x1e1/0x420 net/core/sock.c:3363
 __netlink_sendskb net/netlink/af_netlink.c:1266 [inline]
 netlink_sendskb+0x9b/0x130 net/netlink/af_netlink.c:1272
 netlink_sendmsg+0x8d0/0xbf0 net/netlink/af_netlink.c:1899
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 ____sys_sendmsg+0x61b/0x980 net/socket.c:2595
 ___sys_sendmsg+0x2a6/0x360 net/socket.c:2649
 __sys_sendmsg net/socket.c:2678 [inline]
 __do_sys_sendmsg net/socket.c:2687 [inline]
 __se_sys_sendmsg+0x1d0/0x2c0 net/socket.c:2685
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f1d96ea7407
RSP: 002b:00007ffcb493eec0 EFLAGS: 00000202 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f1d975e5880 RCX: 00007f1d96ea7407
RDX: 0000000000000000 RSI: 00007ffcb493ef20 RDI: 0000000000000004
RBP: 000055ba5e184ec0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 00000000000000b4
R13: 000055ba5dfed9e0 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
rcu: rcu_preempt kthread starved for 10483 jiffies! g19873 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:26856 pid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x15ae/0x4660 kernel/sched/core.c:6701
 schedule+0xbd/0x170 kernel/sched/core.c:6775
 schedule_timeout+0x188/0x2d0 kernel/time/timer.c:2168
 rcu_gp_fqs_loop+0x30d/0x1590 kernel/rcu/tree.c:1667
 rcu_gp_kthread+0x9d/0x3b0 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: 1 PID: 6393 Comm: kworker/u4:23 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
Workqueue: events_unbound toggle_allocation_gate
RIP: 0010:csd_lock_wait kernel/smp.c:311 [inline]
RIP: 0010:smp_call_function_many_cond+0xd85/0x1190 kernel/smp.c:855
Code: 45 8b 34 24 44 89 f6 83 e6 01 31 ff e8 14 fe 0a 00 41 83 e6 01 49 be 00 00 00 00 00 fc ff df 75 07 e8 4f fa 0a 00 eb 38 f3 90 <42> 0f b6 04 33 84 c0 75 11 41 f7 04 24 01 00 00 00 74 1e e8 33 fa
RSP: 0018:ffffc9000d137780 EFLAGS: 00000293
RAX: ffffffff817c7a9d RBX: 1ffff110171c87a9 RCX: ffff88802c5bda00
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc9000d137900 R08: ffffffff911eb507 R09: 1ffffffff223d6a0
R10: dffffc0000000000 R11: fffffbfff223d6a1 R12: ffff8880b8e43d48
R13: ffff8880b8f3d3c0 R14: dffffc0000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffbba1ee52c CR3: 000000000cf32000 CR4: 00000000003506e0
Call Trace:
 <TASK>
 on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1022
 on_each_cpu include/linux/smp.h:71 [inline]
 text_poke_sync arch/x86/kernel/alternative.c:2222 [inline]
 text_poke_bp_batch+0x31e/0x980 arch/x86/kernel/alternative.c:2432
 text_poke_flush arch/x86/kernel/alternative.c:2623 [inline]
 text_poke_finish+0x30/0x50 arch/x86/kernel/alternative.c:2630
 arch_jump_label_transform_apply+0x1c/0x30 arch/x86/kernel/jump_label.c:146
 static_key_enable_cpuslocked+0x123/0x240 kernel/jump_label.c:207
 static_key_enable+0x1a/0x20 kernel/jump_label.c:220
 toggle_allocation_gate+0xa8/0x260 mm/kfence/core.c:847
 process_one_work kernel/workqueue.c:2653 [inline]
 process_scheduled_works+0xa60/0x1600 kernel/workqueue.c:2730
 worker_thread+0xa5e/0xfe0 kernel/workqueue.c:2811
 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>

Crashes (15):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/07/29 06:04 linux-6.6.y c5596480c50e 19622d9d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in dentry_kill
2026/07/25 01:28 linux-6.6.y da47cbc25466 dd737a83 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in dentry_kill
2026/06/25 09:12 linux-6.6.y d1cfde2d5d15 cfa969bf .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in dentry_kill
2026/06/24 04:29 linux-6.6.y d1cfde2d5d15 042555ff .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in dentry_kill
2026/06/07 19:47 linux-6.6.y 924b4a879cbb cc095639 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in dentry_kill
2026/06/05 08:59 linux-6.6.y 924b4a879cbb 197909be .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in dentry_kill
2026/06/02 07:41 linux-6.6.y 924b4a879cbb 1095583b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in dentry_kill
2026/05/13 05:37 linux-6.6.y 3b9f64db0496 a0949470 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in dentry_kill
2026/05/04 17:51 linux-6.6.y 258cf62a6dfd 85f1bcf2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in dentry_kill
2026/04/15 09:36 linux-6.6.y 8cee53b8eaeb e2e976a8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in dentry_kill
2026/04/13 05:14 linux-6.6.y 8cee53b8eaeb 38c8e246 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: rcu detected stall in dentry_kill
2026/04/12 10:28 linux-6.6.y 8cee53b8eaeb 38c8e246 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: rcu detected stall in dentry_kill
2026/03/26 05:39 linux-6.6.y c09fbcd31ae6 c6143aac .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in dentry_kill
2026/02/09 16:02 linux-6.6.y c56aaf1a85ae df949cd9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in dentry_kill
2026/02/01 10:07 linux-6.6.y 2cf6f68313dc 6b8752f2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in dentry_kill
* Struck through repros no longer work on HEAD.