INFO: rcu detected stall in dentry_kill

Status: upstream: reported C repro on 2026/01/20 19:30
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+ecc91afd56cfea8535b2@syzkaller.appspotmail.com
First crash: 287d, last: 10d
▶ ▼ Bug presence (2)
Date Name Commit Repro Result
2026/10/19 linux-6.1.y (ToT) 79807e970724 C [report] INFO: rcu detected stall in corrupted
2026/10/19 upstream (ToT) c03c1a14507d C Didn't crash
▶ ▼ 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 128 1d13h 136d 0/29 upstream: reported C repro on 2026/06/20 03:58
linux-6.6 INFO: rcu detected stall in dentry_kill 1 23 14d 275d 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 14 20h48m 181d 0/3 upstream: reported C repro on 2026/05/06 04:01
▶ ▼ Fix bisection attempts (1)
Created Duration User Patch Repo Result
2026/10/25 02:51 2h35m fix candidate upstream OK (0) job log

Sample crash report:
rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { 0-.... } 2631 jiffies s: 3141 root: 0x1/.
rcu: blocking rcu_node structures (internal RCU debug):
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 4407 Comm: syz-executor Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
RIP: 0010:check_preemption_disabled+0x13/0x110 lib/smp_processor_id.c:13
Code: 00 cc cc 00 00 cc cc 48 c7 c7 80 6d df 8a 48 c7 c6 c0 6d df 8a eb 00 55 41 57 41 56 53 48 83 ec 10 65 48 8b 04 25 28 00 00 00 <48> 89 44 24 08 65 8b 05 11 4b ce 75 65 8b 0d b2 a0 ce 75 f7 c1 ff
RSP: 0018:ffffc90000007880 EFLAGS: 00000082
RAX: 30299c20b5ec5700 RBX: ffffc900000078d8 RCX: 30299c20b5ec5700
RDX: 1ffffffff1f45000 RSI: ffffffff8a8b0ec0 RDI: ffffffff8adf6de0
RBP: 0000000000000000 R08: ffffffff8fa28008 R09: ffffffff8fa28018
R10: ffffffff8fa28010 R11: ffffffff8fa28003 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
FS:  000055557e651500(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb639ded158 CR3: 000000007e566000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 irq_exit_rcu+0x11/0x20 kernel/softirq.c:693
 instr_sysvec_irq_work arch/x86/kernel/irq_work.c:17 [inline]
 sysvec_irq_work+0x4f/0xc0 arch/x86/kernel/irq_work.c:17
 asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:728
RIP: 0010:rcu_read_unlock_special+0x7f/0x510 kernel/rcu/tree_plugin.h:685
Code: eb 03 48 b8 f1 f1 f1 f1 f8 f2 f2 f2 4a 89 04 2b 42 c7 44 2b 08 f8 f3 f3 f3 65 44 8b 35 d2 68 95 7e 41 f7 c6 00 00 f0 00 74 40 <48> c7 44 24 40 0e 36 e0 45 4a c7 04 2b 00 00 00 00 42 c7 44 2b 08
RSP: 0018:ffffc90000007980 EFLAGS: 00000206
RAX: 30299c20b5ec5700 RBX: 1ffff92000000f38 RCX: 30299c20b5ec5700
RDX: dffffc0000000000 RSI: ffffffff8a8c18a0 RDI: ffffffff8adf6de0
RBP: ffffc90000007a80 R08: ffffffff90b33347 R09: 1ffffffff2166668
R10: dffffc0000000000 R11: fffffbfff2166669 R12: 0000000000000246
R13: dffffc0000000000 R14: ffff8880b8e3bb00 R15: 0000000000000001
 __rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:426
 rcu_read_unlock include/linux/rcupdate.h:823 [inline]
 hsr_announce+0x2ca/0x340 net/hsr/hsr_device.c:427
 call_timer_fn+0x1ac/0x670 kernel/time/timer.c:1701
 expire_timers kernel/time/timer.c:1752 [inline]
 __run_timers+0x56c/0x810 kernel/time/timer.c:2023
 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:2036
 handle_softirqs+0x291/0x910 kernel/softirq.c:596
 __do_softirq kernel/softirq.c:630 [inline]
 invoke_softirq kernel/softirq.c:470 [inline]
 __irq_exit_rcu+0x13b/0x230 kernel/softirq.c:679
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:691
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
 sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1118
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:__orc_find arch/x86/kernel/unwind_orc.c:52 [inline]
RIP: 0010:orc_find arch/x86/kernel/unwind_orc.c:178 [inline]
RIP: 0010:unwind_next_frame+0x121c/0x1fd0 arch/x86/kernel/unwind_orc.c:448
Code: 01 c8 48 83 e0 fe 4c 8d 7c 45 00 4c 89 f8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df 0f b6 04 08 84 c0 75 27 49 63 07 4c 01 f8 <49> 8d 4f 04 4c 39 f0 48 0f 46 e9 49 8d 47 fc 4c 0f 47 e8 4d 0f 46
RSP: 0018:ffffc900034377e0 EFLAGS: 00000287
RAX: ffffffff81d2d6db RBX: ffffc90003437888 RCX: dffffc0000000000
RDX: ffffffff8eab3d62 RSI: ffffffff8e37b818 RDI: ffffffff8138fb37
RBP: ffffffff8e37b818 R08: 0000000000000001 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff52000686f1d R12: ffffffff8e37b818
R13: ffffffff8e37b818 R14: ffffffff81d2d7c6 R15: ffffffff8e37b818
 arch_stack_walk+0x10c/0x140 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0xa6/0xf0 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
 kasan_save_free_info+0x27/0x40 mm/kasan/generic.c:516
 ____kasan_slab_free+0x126/0x1f0 mm/kasan/common.c:237
 kasan_slab_free include/linux/kasan.h:177 [inline]
 slab_free_hook mm/slub.c:1729 [inline]
 slab_free_freelist_hook+0x133/0x1b0 mm/slub.c:1755
 slab_free mm/slub.c:3687 [inline]
 kmem_cache_free+0xf7/0x2a0 mm/slub.c:3709
 __dentry_kill+0x4db/0x630 fs/dcache.c:625
 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
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:180
 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: 0033:0x7fb639b5e98e
Code: 08 0f 85 a5 a8 ff ff 49 89 fb 48 89 f0 48 89 d7 48 89 ce 4c 89 c2 4d 89 ca 4c 8b 44 24 08 4c 8b 4c 24 10 4c 89 5c 24 08 0f 05 <c3> 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 80 00 00 00 00 48 83 ec 08
RSP: 002b:00007ffc7668be58 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 000055557e651500 RCX: 00007fb639b5e98e
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00007ffc7668befc R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00000000000927c0 R14: 000000000001996a R15: 00007ffc7668bf50
 </TASK>

Crashes (24):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/10/05 01:53 linux-6.1.y a500ba24937a 57bbd979 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in dentry_kill
2026/10/12 01:44 linux-6.1.y a500ba24937a 4f92358f .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in dentry_kill
2026/10/24 17:54 linux-6.1.y 79807e970724 1d9ca40b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in dentry_kill
2026/10/08 10:31 linux-6.1.y a500ba24937a 4f6a9fcf .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in dentry_kill
2026/10/08 10:15 linux-6.1.y a500ba24937a 4f6a9fcf .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in dentry_kill
2026/10/08 05:28 linux-6.1.y a500ba24937a 4f6a9fcf .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in dentry_kill
2026/10/02 09:32 linux-6.1.y 1a8763b93150 6d32eb1f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in dentry_kill
2026/09/17 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.