INFO: rcu detected stall in dentry_kill

Status: upstream: reported on 2026/01/20 19:30
Reported-by: syzbot+ecc91afd56cfea8535b2@syzkaller.appspotmail.com
First crash: 240d, last: 9h21m
▶ ▼ 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 86 1d03h 90d 0/29 upstream: reported C repro on 2026/06/20 03:58
linux-6.6 INFO: rcu detected stall in dentry_kill 1 20 3d21h 228d 0/2 upstream: reported on 2026/02/01 10:07
linux-5.15 INFO: rcu detected stall in dentry_kill origin:lts-only 1 syz, C error 9 11d 135d 0/3 upstream: reported C repro on 2026/05/06 04:01

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P9649/1:b..l
	(detected by 1, t=10502 jiffies, g=48125, q=30 ncpus=2)
task:syz.1.1069      state:R  running task     stack:23920 pid:9649  ppid:4274   flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5246 [inline]
 __schedule+0x107f/0x4030 kernel/sched/core.c:6563
 preempt_schedule_irq+0xbb/0x160 kernel/sched/core.c:6875
 irqentry_exit+0x63/0x70 kernel/entry/common.c:442
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:stack_trace_consume_entry+0x0/0x270 kernel/stacktrace.c:83
Code: 00 00 42 c7 44 33 08 00 00 00 00 65 48 8b 0c 25 28 00 00 00 48 3b 4c 24 78 75 09 48 8d 65 f0 5b 41 5e 5d c3 e8 51 ae c1 08 90 <55> 41 57 41 56 41 55 41 54 53 48 83 ec 18 48 ba 00 00 00 00 00 fc
RSP: 0018:ffffc9001c99ee40 EFLAGS: 00000282
RAX: ffffffff8170d9b6 RBX: ffffc9001c99ef00 RCX: dffffc0000000000
RDX: ffffc9001c99ee01 RSI: ffffffff8170d9b6 RDI: ffffc9001c99ef00
RBP: ffffc9001c99eed0 R08: ffffc9001c99eed0 R09: ffffc9001c99ee98
R10: dffffc0000000000 R11: fffff52003933dd5 R12: ffff888055569e00
R13: 1ffff1100aaad46e R14: ffffffff8170da00 R15: ffffc9001c99ee48
 arch_stack_walk+0x100/0x140 arch/x86/kernel/stacktrace.c:27
 stack_trace_save+0xa6/0xf0 kernel/stacktrace.c:122
 save_stack+0x121/0x230 mm/page_owner.c:127
 __reset_page_owner+0x51/0x190 mm/page_owner.c:148
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1487 [inline]
 free_pcp_prepare mm/page_alloc.c:1537 [inline]
 free_unref_page_prepare+0x8e5/0x9e0 mm/page_alloc.c:3414
 free_unref_page_list+0xbb/0x8e0 mm/page_alloc.c:3555
 release_pages+0x20d1/0x2340 mm/swap.c:1035
 __pagevec_release+0x6d/0xe0 mm/swap.c:1055
 pagevec_release include/linux/pagevec.h:71 [inline]
 folio_batch_release include/linux/pagevec.h:135 [inline]
 shmem_undo_range+0x808/0x21d0 mm/shmem.c:946
 shmem_truncate_range mm/shmem.c:1062 [inline]
 shmem_evict_inode+0x225/0x9f0 mm/shmem.c:1171
 evict+0x4b6/0x8b0 fs/inode.c:705
 __dentry_kill+0x412/0x630 fs/dcache.c:611
 dentry_kill+0xb8/0x290 fs/dcache.c:-1
 dput+0xfa/0x1d0 fs/dcache.c:918
 __fput+0x597/0x8b0 fs/file_table.c:328
 task_work_run+0x1d0/0x260 kernel/task_work.c:203
 exit_task_work include/linux/task_work.h:39 [inline]
 do_exit+0x9d5/0x2570 kernel/exit.c:887
 do_group_exit+0x229/0x2e0 kernel/exit.c:1030
 get_signal+0x1259/0x1340 kernel/signal.c:2884
 arch_do_signal_or_restart+0xc4/0x1310 arch/x86/kernel/signal.c:871
 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:177
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:213
 irqentry_exit_to_user_mode+0x5/0x30 kernel/entry/common.c:319
 exc_page_fault+0x88/0x100 arch/x86/mm/fault.c:1485
 asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:608
RIP: 0033:0x7f1900f9e161
RSP: 002b:fffffffffffffe70 EFLAGS: 00010217
RAX: 0000000000000000 RBX: 00007f1901226090 RCX: 00007f1900f9e159
RDX: 0000000000000000 RSI: fffffffffffffe70 RDI: 0000000000008000
RBP: 00007f190103506b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 00007f1901226128 R14: 00007f1901226090 R15: 00007ffe90d9be78
 </TASK>
rcu: rcu_preempt kthread starved for 10281 jiffies! g48125 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:26928 pid:16    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5246 [inline]
 __schedule+0x107f/0x4030 kernel/sched/core.c:6563
 schedule+0xb9/0x180 kernel/sched/core.c:6639
 schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2168
 rcu_gp_fqs_loop+0x303/0x1350 kernel/rcu/tree.c:1706
 rcu_gp_kthread+0x99/0x3b0 kernel/rcu/tree.c:1905
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 1 PID: 9732 Comm: syz.7.1088 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:160 [inline]
RIP: 0010:_raw_spin_unlock_irq+0x25/0x40 kernel/locking/spinlock.c:202
Code: 00 00 00 66 90 53 48 89 fb 48 83 c7 18 48 8b 74 24 08 e8 7e d6 27 f7 48 89 df e8 06 9e 28 f7 e8 11 f6 4b f7 fb bf 01 00 00 00 <e8> b6 19 1c f7 65 8b 05 87 c9 c5 75 85 c0 74 02 5b c3 e8 94 dd c3
RSP: 0018:ffffc9001c817b98 EFLAGS: 00000282
RAX: 4259b869aed45c00 RBX: ffff8880733cc0c0 RCX: 4259b869aed45c00
RDX: dffffc0000000000 RSI: ffffffff8a8c18a0 RDI: 0000000000000001
RBP: 0000000000000000 R08: ffff8880733cc0c3 R09: 1ffff1100e679818
R10: dffffc0000000000 R11: ffffed100e679819 R12: 0000000000000021
R13: ffff8880733cc558 R14: dffffc0000000000 R15: 000000001c000004
FS:  00007f830649a6c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b33f17ff8 CR3: 0000000064c0d000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 spin_unlock_irq include/linux/spinlock.h:401 [inline]
 get_signal+0x114a/0x1340 kernel/signal.c:2887
 arch_do_signal_or_restart+0xc4/0x1310 arch/x86/kernel/signal.c:871
 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:177
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:213
 __syscall_exit_to_user_mode_work kernel/entry/common.c:295 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:306
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f830559e159
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:00007f830649a028 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: fffffffffffffe00 RBX: 00007f8305826090 RCX: 00007f830559e159
RDX: 0000000000000000 RSI: 0000000000000006 RDI: 0000000000000005
RBP: 00007f830563506b R08: 0000000000000000 R09: 0000000000000000
R10: 0000020000023896 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f8305826128 R14: 00007f8305826090 R15: 00007ffe1dd850e8
 </TASK>

Crashes (17):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/09/17 22:33 linux-6.1.y 1a8763b93150 8d7d05f1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in dentry_kill
2026/09/16 10:01 linux-6.1.y 1a8763b93150 12a0a44a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in dentry_kill
2026/09/14 10:55 linux-6.1.y cf82dcca9634 70a60e12 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in dentry_kill
2026/08/10 11:23 linux-6.1.y e4f7d8be268e 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in dentry_kill
2026/07/27 21:23 linux-6.1.y dc5c83b7f5f8 aae9036b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in dentry_kill
2026/07/18 17:39 linux-6.1.y 090666d3cc90 72524a66 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in dentry_kill
2026/06/15 04:57 linux-6.1.y 228da13e907e 1d2f3589 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in dentry_kill
2026/05/29 05:17 linux-6.1.y dcbcab9d7079 4624854e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in dentry_kill
2026/04/21 00:52 linux-6.1.y 7c87defbd336 e65da4ee .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in dentry_kill
2026/04/12 08:45 linux-6.1.y 8e8fc038cad5 38c8e246 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in dentry_kill
2026/02/16 00:23 linux-6.1.y 8ce36b2849ef 1e62d198 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in dentry_kill
2026/02/13 02:34 linux-6.1.y 8ce36b2849ef 504cb1bf .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in dentry_kill
2026/02/08 10:28 linux-6.1.y 0182cb5b74ee 4c131dc4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in dentry_kill
2026/02/08 00:14 linux-6.1.y 0182cb5b74ee 4c131dc4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in dentry_kill
2026/01/29 21:58 linux-6.1.y cd9b81672742 aeb6fdd5 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in dentry_kill
2026/01/27 17:36 linux-6.1.y cd9b81672742 9a514c2f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in dentry_kill
2026/01/20 19:29 linux-6.1.y cd9b81672742 06648d9c .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in dentry_kill
* Struck through repros no longer work on HEAD.