INFO: rcu detected stall in sys_newfstatat (2)

Status: upstream: reported syz repro on 2025/02/26 19:28
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+a88bd1d7bf686e214dbf@syzkaller.appspotmail.com
First crash: 514d, last: 236d
▶ ▼ Bug presence (2)
Date Name Commit Repro Result
2025/03/17 linux-6.1.y (ToT) 344a09659766 syz [report] BUG: workqueue lockup
2025/03/17 upstream (ToT) 4701f33a1070 syz Didn't crash
▶ ▼ Similar bugs (9)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in sys_newfstatat (4) prio:high mm tomoyo 1 C error 588 4d08h 1370d 0/29 upstream: reported C repro on 2022/10/25 00:38
linux-6.1 INFO: rcu detected stall in sys_newfstatat origin:upstream 1 C done 8 596d 1133d 3/3 fixed on 2025/01/19 08:56
linux-5.15 INFO: rcu detected stall in sys_newfstatat (2) origin:lts-only 1 C done 16 21d 325d 0/3 upstream: reported C repro on 2025/09/04 12:06
upstream INFO: rcu detected stall in sys_newfstatat mm cgroups 1 1 2426d 2426d 0/29 closed as invalid on 2019/12/04 14:04
linux-6.6 INFO: rcu detected stall in sys_newfstatat (2) 1 4 37d 76d 0/2 upstream: reported on 2026/05/10 20:40
linux-5.15 INFO: rcu detected stall in sys_newfstatat 1 19 446d 839d 0/3 auto-obsoleted due to no activity on 2025/08/14 00:29
linux-6.6 INFO: rcu detected stall in sys_newfstatat 1 7 182d 283d 0/2 auto-obsoleted due to no activity on 2026/05/05 12:53
upstream INFO: rcu detected stall in sys_newfstatat (2) kernfs 1 1 1625d 1625d 0/29 auto-closed as invalid on 2022/05/13 02:53
upstream INFO: rcu detected stall in sys_newfstatat (3) tomoyo 1 1 1512d 1512d 0/29 auto-closed as invalid on 2022/09/03 09:55
▶ ▼ Fix bisection attempts (1)
Created Duration User Patch Repo Result
2025/11/07 13:57 2h04m fix candidate upstream OK (0) job log

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P3913/2:b..l
	(detected by 0, t=10502 jiffies, g=5853, q=160 ncpus=2)
task:udevd           state:R  running task     stack:0     pid:3913  ppid:1      flags:0x00000004
Call trace:
 __switch_to+0x308/0x598 arch/arm64/kernel/process.c:553
 context_switch kernel/sched/core.c:5243 [inline]
 __schedule+0xef4/0x1d44 kernel/sched/core.c:6560
 preempt_schedule_irq+0x8c/0x1b8 kernel/sched/core.c:6872
 arm64_preempt_schedule_irq arch/arm64/kernel/entry-common.c:265 [inline]
 __el1_irq arch/arm64/kernel/entry-common.c:474 [inline]
 el1_interrupt+0x4c/0x68 arch/arm64/kernel/entry-common.c:486
 el1h_64_irq_handler+0x18/0x24 arch/arm64/kernel/entry-common.c:491
 el1h_64_irq+0x64/0x68 arch/arm64/kernel/entry.S:581
 arch_local_irq_restore arch/arm64/include/asm/irqflags.h:122 [inline]
 seqcount_lockdep_reader_access include/linux/seqlock.h:104 [inline]
 read_seqbegin include/linux/seqlock.h:893 [inline]
 read_seqbegin_or_lock+0x160/0x250 include/linux/seqlock.h:1187
 prepend_path+0x2b4/0xb48 fs/d_path.c:170
 d_absolute_path+0x13c/0x27c fs/d_path.c:233
 tomoyo_get_absolute_path security/tomoyo/realpath.c:101 [inline]
 tomoyo_realpath_from_path+0x24c/0x4cc security/tomoyo/realpath.c:271
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_path_perm+0x208/0x568 security/tomoyo/file.c:822
 tomoyo_inode_getattr+0x28/0x38 security/tomoyo/tomoyo.c:122
 security_inode_getattr+0xd8/0x124 security/security.c:1361
 vfs_getattr fs/stat.c:158 [inline]
 vfs_statx+0x184/0x420 fs/stat.c:233
 vfs_fstatat fs/stat.c:267 [inline]
 __do_sys_newfstatat fs/stat.c:437 [inline]
 __se_sys_newfstatat fs/stat.c:431 [inline]
 __arm64_sys_newfstatat+0x134/0x1c0 fs/stat.c:431
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2bc arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585
rcu: rcu_preempt kthread starved for 10502 jiffies! g5853 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->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:R  running task     stack:0     pid:16    ppid:2      flags:0x00000008
Call trace:
 __switch_to+0x308/0x598 arch/arm64/kernel/process.c:553
 context_switch kernel/sched/core.c:5243 [inline]
 __schedule+0xef4/0x1d44 kernel/sched/core.c:6560
 schedule+0xc4/0x170 kernel/sched/core.c:6636
 schedule_timeout+0x1d8/0x344 kernel/time/timer.c:1965
 rcu_gp_fqs_loop+0x2cc/0x1538 kernel/rcu/tree.c:1706
 rcu_gp_kthread+0xc0/0x308 kernel/rcu/tree.c:1905
 kthread+0x250/0x2d8 kernel/kthread.c:376
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:864
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 PID: 4476 Comm: syz.2.18 Not tainted 6.1.129-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:160 [inline]
pc : _raw_spin_unlock_irq+0x44/0x90 kernel/locking/spinlock.c:202
lr : __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:159 [inline]
lr : _raw_spin_unlock_irq+0x3c/0x90 kernel/locking/spinlock.c:202
sp : ffff8000219979c0
x29: ffff8000219979c0 x28: ffff0000cde1a998 x27: ffff800021997d60
x26: 1ffff00004332f54 x25: dfff800000000000 x24: 1fffe00019bc3533
x23: 0000000000000021 x22: 0000000000000020 x21: 0000ffffbd781390
x20: ffff0000c99f5340 x19: ffff0000cde1a500 x18: 1fffe0001a30c29c
x17: 0000000000000000 x16: ffff80000830270c x15: 0000000000000000
x14: 0000000000000001 x13: 0000000000000000 x12: 0000000000000003
x11: 0000000000ff0100 x10: 0000000000000003 x9 : 0000000000000000
x8 : 00000000000000e0 x7 : 0000000018000004 x6 : 0000ffffbd781390
x5 : ffff800021997d80 x4 : ffff0000cde1a9b8 x3 : 0000000000000000
x2 : ffff8000219978e0 x1 : ffff80001247d5c0 x0 : ffff80019e280000
Call trace:
 arch_local_irq_enable arch/arm64/include/asm/irqflags.h:35 [inline]
 __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:159 [inline]
 _raw_spin_unlock_irq+0x44/0x90 kernel/locking/spinlock.c:202
 spin_unlock_irq include/linux/spinlock.h:401 [inline]
 get_signal+0x1258/0x1528 kernel/signal.c:2874
 do_signal arch/arm64/kernel/signal.c:1076 [inline]
 do_notify_resume+0x2f8/0x2cb8 arch/arm64/kernel/signal.c:1129
 prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:137 [inline]
 exit_to_user_mode arch/arm64/kernel/entry-common.c:142 [inline]
 el0_svc+0x9c/0x168 arch/arm64/kernel/entry-common.c:638
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585

Crashes (6):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/02/26 19:27 linux-6.1.y 3a8358583626 d34966d1 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 INFO: rcu detected stall in sys_newfstatat
2025/12/01 17:26 linux-6.1.y f6e38ae624cf d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in sys_newfstatat
2025/11/25 00:30 linux-6.1.y f6e38ae624cf bf6fe8fe .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in sys_newfstatat
2025/10/13 05:45 linux-6.1.y 882efbdd9d34 ff1712fe .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in sys_newfstatat
2025/06/05 07:05 linux-6.1.y 58485ff1a74f 6b6b5f21 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in sys_newfstatat
2025/03/21 07:38 linux-6.1.y 344a09659766 62330552 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in sys_newfstatat
* Struck through repros no longer work on HEAD.