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INFO: rcu detected stall in sys_newfstat (2)

Status: upstream: reported on 2026/04/09 12:06
Reported-by: syzbot+76121c1512b88c6368b9@syzkaller.appspotmail.com
First crash: 46d, last: 2d07h
▶ ▼ Similar bugs (6)
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 9d16h 162d 0/3 upstream: reported on 2025/12/14 02:05
linux-6.6 INFO: rcu detected stall in sys_newfstat 1 1 335d 335d 0/2 auto-obsoleted due to no activity on 2025/10/02 03:58
linux-5.15 INFO: rcu detected stall in sys_newfstat 1 9 1d02h 350d 0/3 upstream: reported on 2025/06/09 10:15
upstream INFO: rcu detected stall in sys_newfstat (4) prio:low mm 1 C error 26 14h32m 154d 0/29 upstream: reported C repro on 2025/12/22 03:48
upstream INFO: rcu detected stall in sys_newfstat (2) mm 1 1 2329d 2329d 0/29 closed as invalid on 2020/01/08 05:33
upstream INFO: rcu detected stall in sys_newfstat mm 1 1 2364d 2364d 0/29 closed as invalid on 2019/12/04 14:04

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-...!: (0 ticks this GP) idle=1d8c/1/0x4000000000000000 softirq=15908/15908 fqs=1
rcu: 	(detected by 1, t=10506 jiffies, g=17569, q=550 ncpus=2)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 5139 Comm: udevd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:do_raw_spin_unlock+0x5/0x230 kernel/locking/spinlock_debug.c:138
Code: ff ff e8 5e c3 1d 09 89 f9 80 e1 07 80 c1 03 38 c1 0f 8c 69 ff ff ff e8 89 e4 75 00 e9 5f ff ff ff 0f 1f 40 00 66 0f 1f 00 55 <41> 57 41 56 41 55 41 54 53 48 89 fb 49 bc 00 00 00 00 00 fc ff df
RSP: 0018:ffffc90000007a10 EFLAGS: 00000046
RAX: 246c6e1ea344c500 RBX: 0000000000000802 RCX: 246c6e1ea344c500
RDX: 0000000000000002 RSI: ffffffff8acadd60 RDI: ffff8880b8e2b700
RBP: ffffc90000007ab0 R08: ffffffff8e8b3aef R09: 1ffffffff1d1675d
R10: dffffc0000000000 R11: fffffbfff1d1675e R12: dffffc0000000000
R13: dffffc0000000000 R14: ffff8880b8e2b700 R15: 1ffff92000000f44
FS:  00007f45c9fac880(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2dc1fff8 CR3: 00000000192f8000 CR4: 00000000003506f0
Call Trace:
 <IRQ>
 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:150 [inline]
 _raw_spin_unlock_irqrestore+0x79/0x120 kernel/locking/spinlock.c:194
 __run_hrtimer kernel/time/hrtimer.c:1750 [inline]
 __hrtimer_run_queues+0x428/0xc40 kernel/time/hrtimer.c:1818
 hrtimer_interrupt+0x3c9/0x9c0 kernel/time/hrtimer.c:1880
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1077 [inline]
 __sysvec_apic_timer_interrupt+0xfb/0x3b0 arch/x86/kernel/apic/apic.c:1094
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline]
 sysvec_apic_timer_interrupt+0x51/0xc0 arch/x86/kernel/apic/apic.c:1088
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:variable_ffs arch/x86/include/asm/bitops.h:319 [inline]
RIP: 0010:handle_softirqs+0x1b0/0x820 kernel/softirq.c:566
Code: 89 64 24 2c 0f b7 db 48 c7 c7 20 c4 c9 8a e8 37 f2 34 09 65 66 c7 05 6d 46 b1 7e 00 00 e8 e8 2e 3b 00 fb 49 c7 c6 c0 a0 e0 8c <89> 5c 24 34 b8 ff ff ff ff 0f bc 44 24 34 41 89 c5 41 ff c5 0f 84
RSP: 0018:ffffc90000007e40 EFLAGS: 00000286
RAX: 246c6e1ea344c500 RBX: 0000000000000004 RCX: 246c6e1ea344c500
RDX: dffffc0000000000 RSI: ffffffff8acacbe0 RDI: ffffffff8b1c9a20
RBP: ffffc90000007f50 R08: ffffffff911c952f R09: 1ffffffff22392a5
R10: dffffc0000000000 R11: fffffbfff22392a6 R12: 000000000000000a
R13: 0000000000000000 R14: ffffffff8ce0a0c0 R15: ffff88807d993c00
 __do_softirq kernel/softirq.c:612 [inline]
 invoke_softirq kernel/softirq.c:452 [inline]
 __irq_exit_rcu+0xd3/0x190 kernel/softirq.c:661
 irq_exit_rcu+0x9/0x20 kernel/softirq.c:673
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline]
 sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1088
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:finish_task_switch+0x26a/0x8f0 kernel/sched/core.c:5255
Code: 0f 84 33 01 00 00 48 85 db 0f 85 52 01 00 00 0f 1f 44 00 00 4c 8b 75 d0 4c 89 e7 e8 20 84 33 09 e8 3b 2e 30 00 fb 4c 8b 65 c0 <49> 8d bc 24 f8 15 00 00 48 89 f8 48 c1 e8 03 42 0f b6 04 28 84 c0
RSP: 0018:ffffc90003307478 EFLAGS: 00000286
RAX: 246c6e1ea344c500 RBX: 0000000000000000 RCX: 246c6e1ea344c500
RDX: dffffc0000000000 RSI: ffffffff8acacbe0 RDI: ffffffff8b1c9a20
RBP: ffffc900033074d0 R08: ffffffff911c952f R09: 1ffffffff22392a5
R10: dffffc0000000000 R11: fffffbfff22392a6 R12: ffff88807d993c00
R13: dffffc0000000000 R14: ffff88802cd30000 R15: ffff8880b8e3cac8
 context_switch kernel/sched/core.c:5384 [inline]
 __schedule+0x155b/0x45a0 kernel/sched/core.c:6700
 preempt_schedule_irq+0xbf/0x150 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:slab_update_freelist mm/slub.c:617 [inline]
RIP: 0010:__slab_free+0x22f/0x400 mm/slub.c:3682
Code: 75 33 48 89 f7 4c 89 d6 4c 89 ea 48 89 d9 4d 89 f8 e8 b5 df ff ff 41 89 c7 eb 55 4c 89 f9 4c 89 d0 4c 89 ea f0 48 0f c7 4e 20 <0f> 84 86 00 00 00 e9 9f fe ff ff 48 89 6c 24 08 48 89 f5 4c 89 64
RSP: 0018:ffffc90003307868 EFLAGS: 00000242
RAX: ffff88806841c400 RBX: ffff88806841b300 RCX: 0000000080070003
RDX: 0000000080070004 RSI: ffffea0001a10600 RDI: 0000000000000000
RBP: ffff888019e4d780 R08: 0000000000000001 R09: 0000000000000000
R10: ffff88806841c400 R11: fffffbfff22392a6 R12: ffff888019e4d780
R13: 0000000080070004 R14: 0000000080070003 R15: 0000000080070003
 qlink_free mm/kasan/quarantine.c:166 [inline]
 qlist_free_all+0x75/0xd0 mm/kasan/quarantine.c:185
 kasan_quarantine_reduce+0x143/0x160 mm/kasan/quarantine.c:292
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:306
 kasan_slab_alloc include/linux/kasan.h:188 [inline]
 slab_post_alloc_hook+0x6e/0x4b0 mm/slab.h:767
 slab_alloc_node mm/slub.c:3495 [inline]
 __kmem_cache_alloc_node+0x13a/0x250 mm/slub.c:3534
 __do_kmalloc_node mm/slab_common.c:1006 [inline]
 __kmalloc+0xa4/0x230 mm/slab_common.c:1020
 kmalloc include/linux/slab.h:604 [inline]
 tomoyo_realpath_from_path+0xe3/0x5d0 security/tomoyo/realpath.c:251
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_path_perm+0x282/0x560 security/tomoyo/file.c:822
 security_inode_getattr+0xd3/0x120 security/security.c:2154
 vfs_getattr fs/stat.c:173 [inline]
 vfs_fstat fs/stat.c:198 [inline]
 __do_sys_newfstat fs/stat.c:473 [inline]
 __se_sys_newfstat fs/stat.c:470 [inline]
 __x64_sys_newfstat+0x12c/0x250 fs/stat.c:470
 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: 0033:0x7f45c9911ad7
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:00007fffd71e9068 EFLAGS: 00000202 ORIG_RAX: 0000000000000005
RAX: ffffffffffffffda RBX: 000000000000000d RCX: 00007f45c9911ad7
RDX: 0000000000090800 RSI: 00007fffd71e9070 RDI: 000000000000000d
RBP: 00007fffd71e9070 R08: 0000000000000000 R09: 0000000000000001
R10: 0000000000000000 R11: 0000000000000202 R12: 000056410ca4b7b0
R13: 00000000000000ff R14: 00005640d5d9ebe0 R15: 00007fffd71e9390
 </TASK>
rcu: rcu_preempt kthread starved for 10500 jiffies! g17569 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:27656 pid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x1553/0x45a0 kernel/sched/core.c:6700
 schedule+0xbd/0x170 kernel/sched/core.c:6774
 schedule_timeout+0x188/0x2d0 kernel/time/timer.c:2168
 rcu_gp_fqs_loop+0x313/0x1590 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: 2950 Comm: kworker/u4:7 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Workqueue: events_unbound toggle_allocation_gate
RIP: 0010:csd_lock_wait kernel/smp.c:311 [inline]
RIP: 0010:smp_call_function_many_cond+0xdfe/0x1140 kernel/smp.c:855
Code: 45 8b 2c 24 44 89 ee 83 e6 01 31 ff e8 4b f7 0a 00 41 83 e5 01 49 bd 00 00 00 00 00 fc ff df 75 07 e8 86 f3 0a 00 eb 38 f3 90 <42> 0f b6 04 2b 84 c0 75 11 41 f7 04 24 01 00 00 00 74 1e e8 6a f3
RSP: 0000:ffffc9000bc17780 EFLAGS: 00000293
RAX: ffffffff817c3886 RBX: 1ffff110171c8759 RCX: ffff88802c409e00
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc9000bc17900 R08: ffffffff911c9507 R09: 1ffffffff22392a0
R10: dffffc0000000000 R11: fffffbfff22392a1 R12: ffff8880b8e43ac8
R13: dffffc0000000000 R14: ffff8880b8f3d148 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f33c2c29000 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/0x990 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+0xa5d/0x15d0 kernel/workqueue.c:2730
 worker_thread+0xa55/0xfc0 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 (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/05/23 15:01 linux-6.6.y 0a40c6fbd105 c69befb3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in sys_newfstat
2026/04/29 23:58 linux-6.6.y 142cd8382222 005438fc .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in sys_newfstat
2026/04/09 12:05 linux-6.6.y 80de0a958133 38c8e246 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: rcu detected stall in sys_newfstat
* Struck through repros no longer work on HEAD.