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INFO: rcu detected stall in sys_newfstat

Status: upstream: reported on 2025/12/14 02:05
Reported-by: syzbot+9996dca5d58ea852ffaf@syzkaller.appspotmail.com
First crash: 162d, last: 9d07h
▶ ▼ Similar bugs (6)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.6 INFO: rcu detected stall in sys_newfstat (2) 1 3 1d22h 46d 0/2 upstream: reported on 2026/04/09 12:06
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 17h18m 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 5h48m 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:
icmp: detected local route for 10.128.1.54 during ICMP sending, src 10.128.0.163
icmp: detected local route for 10.128.1.54 during ICMP sending, src 10.128.0.163
icmp: detected local route for 10.128.1.54 during ICMP sending, src 10.128.0.163
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P10979/1:b..l
	(detected by 1, t=10502 jiffies, g=59341, q=155 ncpus=2)
task:dhcpcd-run-hook state:R  running task     stack:24336 pid:10979 ppid:3933   flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5245 [inline]
 __schedule+0x11d1/0x40e0 kernel/sched/core.c:6562
 preempt_schedule_irq+0xbb/0x160 kernel/sched/core.c:6874
 irqentry_exit+0x63/0x70 kernel/entry/common.c:439
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
RIP: 0010:rcu_read_lock include/linux/rcupdate.h:791 [inline]
RIP: 0010:is_bpf_text_address+0x3d/0x2a0 kernel/bpf/core.c:735
Code: 60 f3 ff e8 55 25 de ff 48 8d 05 00 00 00 00 48 c7 c7 e0 dd b2 8c 31 f6 31 d2 b9 02 00 00 00 45 31 c0 45 31 c9 48 89 44 24 08 <50> e8 9d 27 d5 ff 48 83 c4 08 e8 a4 d5 9e 08 89 c5 31 ff 89 c6 e8
RSP: 0018:ffffc90004edf570 EFLAGS: 00000246
RAX: ffffffff818f25e2 RBX: 00007fb3669d8ad7 RCX: 0000000000000002
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8cb2dde0
RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffff520009dbecd R12: ffff888029dfd940
R13: 0000000000000000 R14: 00007fb3669d8ad7 R15: 1ffff920009dbeca
 kernel_text_address+0x9c/0xd0 kernel/extable.c:125
 __kernel_text_address+0x9/0x30 kernel/extable.c:79
 unwind_get_return_address+0x49/0x80 arch/x86/kernel/unwind_orc.c:323
 arch_stack_walk+0xf2/0x140 arch/x86/kernel/stacktrace.c:26
 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_kmalloc mm/kasan/common.c:375 [inline]
 __kasan_kmalloc+0x8e/0xa0 mm/kasan/common.c:384
 kasan_kmalloc include/linux/kasan.h:211 [inline]
 __do_kmalloc_node mm/slab_common.c:936 [inline]
 __kmalloc+0xb0/0x240 mm/slab_common.c:949
 kmalloc include/linux/slab.h:568 [inline]
 kzalloc include/linux/slab.h:699 [inline]
 tomoyo_encode2 security/tomoyo/realpath.c:45 [inline]
 tomoyo_encode+0x27e/0x540 security/tomoyo/realpath.c:80
 tomoyo_realpath_from_path+0x58e/0x5d0 security/tomoyo/realpath.c:283
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_path_perm+0x26f/0x610 security/tomoyo/file.c:822
 security_inode_getattr+0xcf/0x120 security/security.c:1362
 vfs_getattr+0x26/0x3a0 fs/stat.c:158
 vfs_fstat fs/stat.c:183 [inline]
 __do_sys_newfstat fs/stat.c:447 [inline]
 __se_sys_newfstat fs/stat.c:444 [inline]
 __x64_sys_newfstat+0x13d/0x220 fs/stat.c:444
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fb3669d8ad7
RSP: 002b:00007ffdcf661488 EFLAGS: 00000297 ORIG_RAX: 0000000000000005
RAX: ffffffffffffffda RBX: 000056542465e2a0 RCX: 00007fb3669d8ad7
RDX: 00007fb366ab6ea0 RSI: 00007ffdcf661490 RDI: 0000000000000003
RBP: 00007fb366ab6ff0 R08: 00007fb366ab8ac0 R09: 0000000000000080
R10: 0000000000000004 R11: 0000000000000297 R12: 00007ffdcf6615f8
R13: 0000000000000000 R14: 00007fb3668ba4d0 R15: 0000000000000000
 </TASK>
rcu: rcu_preempt kthread starved for 9821 jiffies! g59341 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:28080 pid:16    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5245 [inline]
 __schedule+0x11d1/0x40e0 kernel/sched/core.c:6562
 schedule+0xb9/0x180 kernel/sched/core.c:6638
 schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2168
 rcu_gp_fqs_loop+0x303/0x1340 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: 0 Comm: swapper/1 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:default_idle+0xb/0x10 arch/x86/kernel/process.c:742
Code: 48 89 df e8 d7 a4 9b f7 e9 44 ff ff ff e8 3d 07 f6 ff 00 00 cc cc 00 00 cc cc 00 00 cc cc 00 66 90 0f 00 2d a7 ba 4e 00 fb f4 <c3> 0f 1f 40 00 41 57 41 56 53 49 be 00 00 00 00 00 fc ff df 65 48
RSP: 0018:ffffc90000177de8 EFLAGS: 000002c6
RAX: c1872dde9a953900 RBX: ffffffff8a37f307 RCX: c1872dde9a953900
RDX: 0000000000000001 RSI: ffffffff8a8c19a0 RDI: ffffffff8adf1ba0
RBP: ffffc90000177f20 R08: ffff8880b8f3580b R09: 1ffff110171e6b01
R10: dffffc0000000000 R11: ffffed10171e6b02 R12: 0000000000000000
R13: dffffc0000000000 R14: ffff88813fef9dc0 R15: 1ffff9200002efc8
FS:  0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f49a1adc48e CR3: 000000001fb4f000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 default_idle_call+0x84/0xc0 kernel/sched/idle.c:109
 cpuidle_idle_call kernel/sched/idle.c:199 [inline]
 do_idle+0x250/0x680 kernel/sched/idle.c:323
 cpu_startup_entry+0x3f/0x60 kernel/sched/idle.c:422
 start_secondary+0xe4/0xf0 arch/x86/kernel/smpboot.c:281
 secondary_startup_64_no_verify+0xcf/0xdb
 </TASK>

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/05/16 06:01 linux-6.1.y c27210688955 81fb92f3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in sys_newfstat
2026/02/19 00:37 linux-6.1.y 8ce36b2849ef 77d4d919 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in sys_newfstat
2026/02/13 02:32 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 sys_newfstat
2025/12/14 02:05 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in sys_newfstat
* Struck through repros no longer work on HEAD.