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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: 28d, last: 7d16h
▶ ▼ 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 3 77d 144d 0/3 upstream: reported on 2025/12/14 02:05
linux-6.6 INFO: rcu detected stall in sys_newfstat 1 1 317d 317d 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 7 32d 332d 0/3 upstream: reported on 2025/06/09 10:15
upstream INFO: rcu detected stall in sys_newfstat (4) tomoyo mm 1 C error 21 1h51m 136d 0/29 upstream: reported C repro on 2025/12/22 03:48
upstream INFO: rcu detected stall in sys_newfstat (2) mm 1 1 2311d 2311d 0/29 closed as invalid on 2020/01/08 05:33
upstream INFO: rcu detected stall in sys_newfstat mm 1 1 2346d 2346d 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=26e4/1/0x4000000000000000 softirq=35833/35833 fqs=8
rcu: 	(detected by 1, t=10502 jiffies, g=42985, q=452 ncpus=2)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 5137 Comm: udevd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:_test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
RIP: 0010:hlock_class kernel/locking/lockdep.c:228 [inline]
RIP: 0010:check_wait_context kernel/locking/lockdep.c:4773 [inline]
RIP: 0010:__lock_acquire+0x55b/0x7d40 kernel/locking/lockdep.c:5087
Code: 24 48 89 d8 48 c1 e8 03 42 0f b6 04 00 84 c0 4c 8b 6c 24 20 0f 85 4d 64 00 00 44 89 33 44 89 fb 81 e3 ff 1f 00 00 41 c1 ef 03 <41> 81 e7 f8 03 00 00 49 8d bf 00 65 1c 91 be 08 00 00 00 e8 ed 25
RSP: 0018:ffffc90000007860 EFLAGS: 00000006
RAX: 0000000000000000 RBX: 0000000000000001 RCX: 0000000000004000
RDX: ffff88807e806528 RSI: 0000000000000002 RDI: ffff88807e806538
RBP: ffffc90000007aa8 R08: dffffc0000000000 R09: 0000000000000001
R10: dffffc0000000000 R11: fffffbfff1d1633e R12: ffff88807e8064c4
R13: ffff88807e805a00 R14: 0000000000000000 R15: 0000000000018800
FS:  00007f9cee7d0880(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc178f85f40 CR3: 00000000311e4000 CR4: 00000000003506f0
Call Trace:
 <IRQ>
 lock_acquire+0x19e/0x420 kernel/locking/lockdep.c:5754
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
 _raw_spin_lock_irqsave+0xb4/0x100 kernel/locking/spinlock.c:162
 debug_object_activate+0x6c/0x4f0 lib/debugobjects.c:709
 debug_hrtimer_activate kernel/time/hrtimer.c:450 [inline]
 debug_activate kernel/time/hrtimer.c:505 [inline]
 enqueue_hrtimer+0x30/0x370 kernel/time/hrtimer.c:1108
 __run_hrtimer kernel/time/hrtimer.c:1767 [inline]
 __hrtimer_run_queues+0x63a/0xc40 kernel/time/hrtimer.c:1814
 hrtimer_interrupt+0x3c9/0x9c0 kernel/time/hrtimer.c:1876
 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+0x9f/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:__sanitizer_cov_trace_pc+0x4/0x60 kernel/kcov.c:212
Code: 1f 80 00 00 00 00 f3 0f 1e fa 53 48 89 fb e8 13 00 00 00 48 8b 3d 1c fa 03 0d 48 89 de 5b e9 d3 67 57 00 cc cc cc f3 0f 1e fa <48> 8b 04 24 65 48 8b 0d b0 93 7c 7e 65 8b 15 b1 93 7c 7e 81 e2 00
RSP: 0018:ffffc9000352f5d0 EFLAGS: 00000296
RAX: 0000000000000001 RBX: ffffc9000352f760 RCX: ffff88807e805a00
RDX: dffffc0000000000 RSI: ffffffff8175c1fa RDI: ffffc9000352f6a8
RBP: ffffc9000352f730 R08: ffffc9000352f770 R09: 0000000000000000
R10: 0000000000000004 R11: 0000000000000000 R12: ffffc9000352f6a8
R13: dffffc0000000000 R14: ffffffff8175c250 R15: ffffc9000352f6a8
 unwind_next_frame+0x27/0x2970 arch/x86/kernel/unwind_orc.c:469
 arch_stack_walk+0x144/0x190 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0xaa/0x100 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4e/0x70 mm/kasan/common.c:53
 ____kasan_kmalloc mm/kasan/common.c:375 [inline]
 __kasan_kmalloc+0x8f/0xa0 mm/kasan/common.c:384
 kasan_kmalloc include/linux/kasan.h:198 [inline]
 __do_kmalloc_node mm/slab_common.c:1007 [inline]
 __kmalloc+0xb4/0x230 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+0x55/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f9cee111ad7
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:00007ffd17898af8 EFLAGS: 00000206 ORIG_RAX: 0000000000000005
RAX: ffffffffffffffda RBX: 000000000000000d RCX: 00007f9cee111ad7
RDX: 0000000000090800 RSI: 00007ffd17898b00 RDI: 000000000000000d
RBP: 00007ffd17898b00 R08: 0000000000000000 R09: 0000000000000001
R10: 0000000000000000 R11: 0000000000000206 R12: 0000557240bea7b0
R13: 00000000000000ff R14: 000055720da47be0 R15: 00007ffd17898e20
 </TASK>
rcu: rcu_preempt kthread starved for 10486 jiffies! g42985 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:27344 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: 1081 Comm: kworker/u4:5 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 cb f5 0a 00 41 83 e5 01 49 bd 00 00 00 00 00 fc ff df 75 07 e8 06 f2 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 ea f1
RSP: 0018:ffffc90004717780 EFLAGS: 00000293
RAX: ffffffff817c3016 RBX: 1ffff110171c8759 RCX: ffff888023be8000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc90004717900 R08: ffffffff911c6507 R09: 1ffffffff2238ca0
R10: dffffc0000000000 R11: fffffbfff2238ca1 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: 00007f4108bfff74 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 (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
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.