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INFO: rcu detected stall in sys_newfstatat (2)

Status: upstream: reported on 2026/05/10 20:40
Reported-by: syzbot+e56fb7f0a6923e2175ba@syzkaller.appspotmail.com
First crash: 1d13h, last: 8h49m
▶ ▼ 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) mm tomoyo 1 C error 530 2d02h 1295d 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 521d 1058d 3/3 fixed on 2025/01/19 08:56
linux-6.1 INFO: rcu detected stall in sys_newfstatat (2) origin:lts-only 1 syz inconclusive 6 161d 439d 0/3 upstream: reported syz repro on 2025/02/26 19:28
linux-5.15 INFO: rcu detected stall in sys_newfstatat (2) origin:lts-only 1 C done 14 3d09h 249d 0/3 upstream: reported C repro on 2025/09/04 12:06
upstream INFO: rcu detected stall in sys_newfstatat mm cgroups 1 1 2351d 2351d 0/29 closed as invalid on 2019/12/04 14:04
linux-5.15 INFO: rcu detected stall in sys_newfstatat 1 19 371d 764d 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 106d 208d 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 1550d 1550d 0/29 auto-closed as invalid on 2022/05/13 02:53
upstream INFO: rcu detected stall in sys_newfstatat (3) tomoyo 1 1 1437d 1437d 0/29 auto-closed as invalid on 2022/09/03 09:55

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P14455/1:b..l P14640/1:b..l
rcu: 	(detected by 0, t=10502 jiffies, g=112469, q=268 ncpus=2)
task:syz-executor    state:R  running task     stack:21736 pid:14640 ppid:14609  flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x1553/0x45a0 kernel/sched/core.c:6700
 preempt_schedule_common+0x82/0xc0 kernel/sched/core.c:6867
 preempt_schedule+0xc0/0xd0 kernel/sched/core.c:6891
 preempt_schedule_thunk+0x1a/0x30 arch/x86/entry/thunk_64.S:45
 unwind_next_frame+0x200f/0x2970 arch/x86/kernel/unwind_orc.c:672
 arch_stack_walk+0x144/0x190 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0xaa/0x100 kernel/stacktrace.c:122
 save_stack+0x125/0x230 mm/page_owner.c:128
 __reset_page_owner+0x4e/0x190 mm/page_owner.c:149
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1181 [inline]
 free_unref_page_prepare+0x7b2/0x8c0 mm/page_alloc.c:2365
 free_unref_page_list+0xbe/0x860 mm/page_alloc.c:2504
 release_pages+0x1f7a/0x2200 mm/swap.c:1022
 __folio_batch_release+0x71/0xe0 mm/swap.c:1042
 folio_batch_release include/linux/pagevec.h:83 [inline]
 shmem_undo_range+0x630/0x1b20 mm/shmem.c:1026
 shmem_truncate_range mm/shmem.c:1135 [inline]
 shmem_evict_inode+0x245/0x9e0 mm/shmem.c:1264
 evict+0x4ca/0x8d0 fs/inode.c:705
 do_unlinkat+0x38c/0x590 fs/namei.c:4406
 __do_sys_unlink fs/namei.c:4447 [inline]
 __se_sys_unlink fs/namei.c:4445 [inline]
 __x64_sys_unlink+0x49/0x50 fs/namei.c:4445
 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: 0033:0x7efef799bec7
RSP: 002b:00007fff7a181848 EFLAGS: 00000206 ORIG_RAX: 0000000000000057
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007efef799bec7
RDX: 00007fff7a181870 RSI: 00007fff7a181900 RDI: 00007fff7a181900
RBP: 00007fff7a181900 R08: 00007fff7a182900 R09: 00000000ffffffff
R10: 0000000000000100 R11: 0000000000000206 R12: 00007fff7a182990
R13: 00007efef7a32120 R14: 00000000000a1aff R15: 00007fff7a1829d0
 </TASK>
task:syz-executor    state:R  running task     stack:21736 pid:14455 ppid:14434  flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x1553/0x45a0 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:lock_release+0x594/0x8c0 kernel/locking/lockdep.c:5778
Code: 00 00 00 f7 84 24 80 00 00 00 00 02 00 00 43 c6 44 2f 04 f8 75 70 f7 44 24 50 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 04 2f 00 00 00 00 43 c7 44 2f 08 00 00 00 00 65 48 8b 04 25
RSP: 0018:ffffc9000d87f720 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 09988012a6de1317 RCX: b41cc820f6f11800
RDX: 0000000000000002 RSI: ffffffff8acadb60 RDI: ffffffff8b1c8fa0
RBP: ffffc9000d87f828 R08: ffffffff8e8b19af R09: 1ffffffff1d16335
R10: dffffc0000000000 R11: fffffbfff1d16336 R12: ffff88805e9a0b30
R13: dffffc0000000000 R14: ffff88805e9a0ad0 R15: 1ffff92001b0fef0
 rcu_lock_release include/linux/rcupdate.h:344 [inline]
 rcu_read_unlock include/linux/rcupdate.h:819 [inline]
 prepend_path+0x5b8/0x960 fs/d_path.c:174
 d_absolute_path+0xa2/0x140 fs/d_path.c:234
 tomoyo_get_absolute_path security/tomoyo/realpath.c:101 [inline]
 tomoyo_realpath_from_path+0x2d9/0x5d0 security/tomoyo/realpath.c:271
 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_statx+0x172/0x680 fs/stat.c:248
 vfs_fstatat+0x12a/0x1b0 fs/stat.c:299
 __do_sys_newfstatat fs/stat.c:463 [inline]
 __se_sys_newfstatat fs/stat.c:457 [inline]
 __x64_sys_newfstatat+0x149/0x1f0 fs/stat.c:457
 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: 0033:0x7fbae099b41a
RSP: 002b:00007ffcbf4a5348 EFLAGS: 00000286 ORIG_RAX: 0000000000000106
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fbae099b41a
RDX: 00007ffcbf4a5370 RSI: 00007ffcbf4a5400 RDI: 00000000ffffff9c
RBP: 00007ffcbf4a5400 R08: 00007ffcbf4a6400 R09: 00000000ffffffff
R10: 0000000000000100 R11: 0000000000000286 R12: 00007ffcbf4a6490
R13: 00007fbae0a32120 R14: 00000000000a278e R15: 00007ffcbf4a64d0
 </TASK>
rcu: rcu_preempt kthread starved for 10356 jiffies! g112469 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:27312 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:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
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:pv_native_safe_halt+0xf/0x10 arch/x86/kernel/paravirt.c:148
Code: 19 21 02 c3 cc cc cc cc cc cc cc f3 0f 1e fa 0f 0b 66 2e 0f 1f 84 00 00 00 00 00 f3 0f 1e fa 66 90 0f 00 2d e3 d3 41 00 fb f4 <c3> 66 0f 1f 00 55 41 57 41 56 41 54 53 50 8b 2f eb 2e 41 89 de 80
RSP: 0018:ffffc90000187de0 EFLAGS: 000002c6
RAX: d03fa44fcd0f4300 RBX: ffffffff8162aa0d RCX: d03fa44fcd0f4300
RDX: 0000000000000001 RSI: ffffffff8acac9e0 RDI: ffffffff8b1c8fa0
RBP: ffffc90000187f20 R08: ffff8880b8f36b2b R09: 1ffff110171e6d65
R10: dffffc0000000000 R11: ffffed10171e6d66 R12: 1ffff92000030fc8
R13: dffffc0000000000 R14: 1ffff1100344e780 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f59d884fdfc CR3: 000000002f22f000 CR4: 00000000003506e0
Call Trace:
 <TASK>
 arch_safe_halt arch/x86/include/asm/paravirt.h:108 [inline]
 default_idle+0x13/0x20 arch/x86/kernel/process.c:753
 default_idle_call+0x6c/0xa0 kernel/sched/idle.c:97
 cpuidle_idle_call kernel/sched/idle.c:178 [inline]
 do_idle+0x33d/0x590 kernel/sched/idle.c:302
 cpu_startup_entry+0x43/0x60 kernel/sched/idle.c:401
 start_secondary+0xee/0xf0 arch/x86/kernel/smpboot.c:323
 secondary_startup_64_no_verify+0x179/0x17b
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/05/12 01:07 linux-6.6.y 3b9f64db0496 d168f260 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in sys_newfstatat
2026/05/10 20:40 linux-6.6.y 3b9f64db0496 29233ece .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in sys_newfstatat
* Struck through repros no longer work on HEAD.