INFO: rcu detected stall in sys_newfstat

Status: upstream: reported on 2025/06/09 10:15
Reported-by: syzbot+26fdb539432016a3def1@syzkaller.appspotmail.com
First crash: 493d, last: 14d
▶ ▼ Similar bugs (7)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 INFO: rcu detected stall in sys_newfstat 1 4 152d 305d 0/3 auto-obsoleted due to no activity on 2026/08/24 06:02
linux-6.6 INFO: rcu detected stall in sys_newfstat (2) 1 syz, C 5 17d 189d 0/2 upstream: reported C repro on 2026/04/09 12:06
linux-6.6 INFO: rcu detected stall in sys_newfstat 1 1 478d 478d 0/2 auto-obsoleted due to no activity on 2025/10/02 03:58
upstream INFO: rcu detected stall in sys_newfstat (4) prio:low mm 1 syz, C error 91 4d17h 297d 0/29 upstream: reported C repro on 2025/12/22 03:48
upstream INFO: rcu detected stall in sys_newfstat (2) mm 1 1 2472d 2472d 0/29 closed as invalid on 2020/01/08 05:33
upstream INFO: rcu detected stall in sys_newfstat mm 1 1 2507d 2507d 0/29 closed as invalid on 2019/12/04 14:04
upstream INFO: task hung in linkwatch_event (4) prio:low net 1 syz, C done 5555 now 810d 0/29 upstream: reported C repro on 2024/07/27 06:21

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-...!: (1 ticks this GP) idle=cbd/1/0x4000000000000002 softirq=150612/150612 fqs=0 
	(detected by 1, t=10502 jiffies, g=224073, q=1403)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 20956 Comm: dhcpcd-run-hook Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:get_current arch/x86/include/asm/current.h:15 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x4/0x60 kernel/kcov.c:204
Code: 00 00 00 00 00 90 53 48 89 fb e8 17 00 00 00 48 8b 3d 80 0c 12 0c 48 89 de 5b e9 47 6b 44 00 00 00 cc cc 00 00 cc 48 8b 04 24 <65> 48 8b 0d 14 5b 89 7e 65 8b 15 15 5b 89 7e 81 e2 00 01 ff 00 74
RSP: 0018:ffffc900000072b8 EFLAGS: 00000046
RAX: ffffffff819886d1 RBX: ffff8880b9035250 RCX: ffff888022773b80
RDX: 0000000000000100 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90000007548 R08: ffffffff8d8b1eef R09: 1ffffffff1b163dd
R10: dffffc0000000000 R11: fffffbfff1b163de R12: 1ffff11017206a4a
R13: ffff888068196b70 R14: 0000000000000000 R15: 0000000000000000
FS:  00007f374f21ec80(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f9d9dea3158 CR3: 0000000078d33000 CR4: 00000000003506f0
DR0: 0000200000000300 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 perf_tp_event_match kernel/events/core.c:10010 [inline]
 perf_tp_event+0x261/0xbe0 kernel/events/core.c:10056
 perf_trace_run_bpf_submit+0xf3/0x1c0 kernel/events/core.c:10031
 perf_trace_preemptirq_template+0x2aa/0x360 include/trace/events/preemptirq.h:14
 trace_irq_enable_rcuidle+0x108/0x180 include/trace/events/preemptirq.h:40
 trace_hardirqs_on+0x57/0x80 kernel/trace/trace_preemptirq.c:44
 asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:713
RIP: 0010:rcu_read_unlock_special+0x7f/0x4a0 kernel/rcu/tree_plugin.h:674
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 42 0b 9d 7e 41 f7 c6 00 00 f0 00 74 40 <48> c7 44 24 20 0e 36 e0 45 4a c7 04 2b 00 00 00 00 42 c7 44 2b 08
RSP: 0018:ffffc90000007780 EFLAGS: 00000206
RAX: 5a31b171f9575700 RBX: 1ffff92000000ef4 RCX: 5a31b171f9575700
RDX: dffffc0000000000 RSI: ffffffff8a2b2be0 RDI: ffffffff8a7a48c0
RBP: ffffc90000007860 R08: ffffffff901f11c7 R09: 1ffffffff203e238
R10: dffffc0000000000 R11: fffffbfff203e239 R12: ffffffff8c323400
R13: dffffc0000000000 R14: 0000000000000246 R15: 0000000000000001
 __rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:422
 rcu_read_unlock include/linux/rcupdate.h:772 [inline]
 ndisc_send_skb+0xd3b/0x1410 net/ipv6/ndisc.c:521
 addrconf_rs_timer+0x367/0x640 net/ipv6/addrconf.c:3966
 call_timer_fn+0x17b/0x540 kernel/time/timer.c:1648
 expire_timers kernel/time/timer.c:1699 [inline]
 __run_timers+0x56c/0x810 kernel/time/timer.c:1970
 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1983
 handle_softirqs+0x336/0x830 kernel/softirq.c:576
 __do_softirq kernel/softirq.c:610 [inline]
 invoke_softirq kernel/softirq.c:450 [inline]
 __irq_exit_rcu+0x13b/0x230 kernel/softirq.c:659
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:671
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
 sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1108
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0xbc/0x120 kernel/locking/spinlock.c:194
Code: c7 44 24 20 00 00 00 00 9c 8f 44 24 20 f7 44 24 20 00 02 00 00 41 c6 04 07 f8 75 4b f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 <e8> 3f b1 87 f7 65 8b 05 70 c7 37 76 85 c0 74 3c 48 c7 04 24 0e 36
RSP: 0018:ffffc9000376f900 EFLAGS: 00000206
RAX: dffffc0000000004 RBX: 0000000000000a02 RCX: 5a31b171f9575700
RDX: dffffc0000000000 RSI: ffffffff8a2b2be0 RDI: 0000000000000001
RBP: ffffc9000376f998 R08: ffff8880b903b30b R09: 1ffff11017207661
R10: dffffc0000000000 R11: ffffed1017207662 R12: dffffc0000000000
R13: ffff888060879cc0 R14: ffffffff964fa570 R15: 1ffff920006edf20
 __debug_check_no_obj_freed lib/debugobjects.c:999 [inline]
 debug_check_no_obj_freed+0x471/0x520 lib/debugobjects.c:1020
 slab_free_hook mm/slub.c:1685 [inline]
 slab_free_freelist_hook+0x8b/0x170 mm/slub.c:1736
 slab_free mm/slub.c:3504 [inline]
 kfree+0xef/0x2a0 mm/slub.c:4564
 tomoyo_path_perm+0x433/0x5d0 security/tomoyo/file.c:842
 security_inode_getattr+0xcf/0x120 security/security.c:1398
 vfs_getattr+0x26/0x3a0 fs/stat.c:157
 vfs_fstat fs/stat.c:182 [inline]
 __do_sys_newfstat fs/stat.c:421 [inline]
 __se_sys_newfstat fs/stat.c:418 [inline]
 __x64_sys_newfstat+0x137/0x210 fs/stat.c:418
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f374f3d8ad7
Code: 73 01 c3 48 8b 0d 21 f3 0d 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 05 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 8b 15 f1 f2 0d 00 f7 d8 64 89 02 b8
RSP: 002b:00007ffcea4bc2c8 EFLAGS: 00000202 ORIG_RAX: 0000000000000005
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007f374f3d8ad7
RDX: 0000000000090800 RSI: 00007ffcea4bc2d0 RDI: 0000000000000003
RBP: 00007ffcea4bc2d0 R08: 00007f374f4b8ac0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 00007ffcea4bc4c8
R13: 00005641b9b66248 R14: 0000000000000001 R15: 00005641b9b66337
 </TASK>
rcu: rcu_preempt kthread timer wakeup didn't happen for 10501 jiffies! g224073 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=0 timer-softirq=92316
rcu: rcu_preempt kthread starved for 10502 jiffies! g224073 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->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:I stack:26960 pid:   15 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11c3/0x4350 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2117
 rcu_gp_fqs_loop+0x2be/0x11f0 kernel/rcu/tree.c:1972
 rcu_gp_kthread+0x9a/0x370 kernel/rcu/tree.c:2145
 kthread+0x42e/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 20956 Comm: dhcpcd-run-hook Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:__sanitizer_cov_trace_cmp8+0x0/0x80 kernel/kcov.c:272
Code: 28 4d 39 ca 77 22 89 ff 89 f6 4a c7 44 02 08 04 00 00 00 4a 89 7c 02 10 4a 89 74 02 18 4a 89 44 02 20 48 ff c1 48 89 0a c3 90 <48> 8b 04 24 65 48 8b 0d 34 59 89 7e 65 8b 15 35 59 89 7e 81 e2 00
RSP: 0018:ffffc90000007260 EFLAGS: 00000017
RAX: ffffffff819894c5 RBX: 0000000000089000 RCX: ffff888022773b80
RDX: 0000000000000100 RSI: 0000000000000007 RDI: 0000000000000007
RBP: 0000000000000007 R08: ffff888020734f97 R09: 1ffff110040e69f2
R10: dffffc0000000000 R11: ffffed10040e69f3 R12: 0000000000000001
R13: ffff888020734f90 R14: 0000000000000007 R15: fffffffffffffff9
FS:  00007f374f21ec80(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f9d9dea3158 CR3: 0000000078d33000 CR4: 00000000003506f0
DR0: 0000200000000300 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 perf_swevent_event+0x487/0x540 kernel/events/core.c:-1
 perf_tp_event+0x324/0xbe0 kernel/events/core.c:10057
 perf_trace_run_bpf_submit+0xf3/0x1c0 kernel/events/core.c:10031
 perf_trace_preemptirq_template+0x2aa/0x360 include/trace/events/preemptirq.h:14
 trace_irq_enable_rcuidle+0x108/0x180 include/trace/events/preemptirq.h:40
 trace_hardirqs_on+0x57/0x80 kernel/trace/trace_preemptirq.c:44
 asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:713
RIP: 0010:rcu_read_unlock_special+0x7f/0x4a0 kernel/rcu/tree_plugin.h:674
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 42 0b 9d 7e 41 f7 c6 00 00 f0 00 74 40 <48> c7 44 24 20 0e 36 e0 45 4a c7 04 2b 00 00 00 00 42 c7 44 2b 08
RSP: 0018:ffffc90000007780 EFLAGS: 00000206
RAX: 5a31b171f9575700 RBX: 1ffff92000000ef4 RCX: 5a31b171f9575700
RDX: dffffc0000000000 RSI: ffffffff8a2b2be0 RDI: ffffffff8a7a48c0
RBP: ffffc90000007860 R08: ffffffff901f11c7 R09: 1ffffffff203e238
R10: dffffc0000000000 R11: fffffbfff203e239 R12: ffffffff8c323400
R13: dffffc0000000000 R14: 0000000000000246 R15: 0000000000000001
 __rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:422
 rcu_read_unlock include/linux/rcupdate.h:772 [inline]
 ndisc_send_skb+0xd3b/0x1410 net/ipv6/ndisc.c:521
 addrconf_rs_timer+0x367/0x640 net/ipv6/addrconf.c:3966
 call_timer_fn+0x17b/0x540 kernel/time/timer.c:1648
 expire_timers kernel/time/timer.c:1699 [inline]
 __run_timers+0x56c/0x810 kernel/time/timer.c:1970
 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1983
 handle_softirqs+0x336/0x830 kernel/softirq.c:576
 __do_softirq kernel/softirq.c:610 [inline]
 invoke_softirq kernel/softirq.c:450 [inline]
 __irq_exit_rcu+0x13b/0x230 kernel/softirq.c:659
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:671
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
 sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1108
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0xbc/0x120 kernel/locking/spinlock.c:194
Code: c7 44 24 20 00 00 00 00 9c 8f 44 24 20 f7 44 24 20 00 02 00 00 41 c6 04 07 f8 75 4b f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 <e8> 3f b1 87 f7 65 8b 05 70 c7 37 76 85 c0 74 3c 48 c7 04 24 0e 36
RSP: 0018:ffffc9000376f900 EFLAGS: 00000206
RAX: dffffc0000000004 RBX: 0000000000000a02 RCX: 5a31b171f9575700
RDX: dffffc0000000000 RSI: ffffffff8a2b2be0 RDI: 0000000000000001
RBP: ffffc9000376f998 R08: ffff8880b903b30b R09: 1ffff11017207661
R10: dffffc0000000000 R11: ffffed1017207662 R12: dffffc0000000000
R13: ffff888060879cc0 R14: ffffffff964fa570 R15: 1ffff920006edf20
 __debug_check_no_obj_freed lib/debugobjects.c:999 [inline]
 debug_check_no_obj_freed+0x471/0x520 lib/debugobjects.c:1020
 slab_free_hook mm/slub.c:1685 [inline]
 slab_free_freelist_hook+0x8b/0x170 mm/slub.c:1736
 slab_free mm/slub.c:3504 [inline]
 kfree+0xef/0x2a0 mm/slub.c:4564
 tomoyo_path_perm+0x433/0x5d0 security/tomoyo/file.c:842
 security_inode_getattr+0xcf/0x120 security/security.c:1398
 vfs_getattr+0x26/0x3a0 fs/stat.c:157
 vfs_fstat fs/stat.c:182 [inline]
 __do_sys_newfstat fs/stat.c:421 [inline]
 __se_sys_newfstat fs/stat.c:418 [inline]
 __x64_sys_newfstat+0x137/0x210 fs/stat.c:418
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f374f3d8ad7
Code: 73 01 c3 48 8b 0d 21 f3 0d 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 05 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 8b 15 f1 f2 0d 00 f7 d8 64 89 02 b8
RSP: 002b:00007ffcea4bc2c8 EFLAGS: 00000202 ORIG_RAX: 0000000000000005
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007f374f3d8ad7
RDX: 0000000000090800 RSI: 00007ffcea4bc2d0 RDI: 0000000000000003
RBP: 00007ffcea4bc2d0 R08: 00007f374f4b8ac0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 00007ffcea4bc4c8
R13: 00005641b9b66248 R14: 0000000000000001 R15: 00005641b9b66337
 </TASK>

Crashes (11):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/10/01 19:57 linux-5.15.y 0248c33e835e f5cdae2f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in sys_newfstat
2026/07/19 22:45 linux-5.15.y c86c4726e7f0 72524a66 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in sys_newfstat
2026/05/24 20:39 linux-5.15.y 241d66fa280c c69befb3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_newfstat
2026/05/23 19:57 linux-5.15.y 241d66fa280c c69befb3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_newfstat
2026/04/05 12:23 linux-5.15.y 91d48252ad4b 4440e7c2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in sys_newfstat
2026/01/19 08:27 linux-5.15.y 68efe5a6c16a 20d37d28 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_newfstat
2025/12/09 14:16 linux-5.15.y 68efe5a6c16a d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_newfstat
2025/09/08 05:43 linux-5.15.y 7a6c2d093c45 d291dd2d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in sys_newfstat
2025/08/30 12:10 linux-5.15.y 01879f56bdde 807a3b61 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_newfstat
2025/06/09 10:14 linux-5.15.y 1c700860e8bc 4826c28e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_newfstat
2025/07/02 00:27 linux-5.15.y 3dea0e7f549e 091a06cd .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: rcu detected stall in sys_newfstat
* Struck through repros no longer work on HEAD.