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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: 96d, last: 14d
▶ ▼ 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 60d 213d 0/3 upstream: reported on 2025/12/14 02:05
linux-6.6 INFO: rcu detected stall in sys_newfstat 1 1 386d 386d 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 51d 401d 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 51 1d12h 205d 0/29 upstream: reported C repro on 2025/12/22 03:48
upstream INFO: rcu detected stall in sys_newfstat (2) mm 1 1 2380d 2380d 0/29 closed as invalid on 2020/01/08 05:33
upstream INFO: rcu detected stall in sys_newfstat mm 1 1 2415d 2415d 0/29 closed as invalid on 2019/12/04 14:04

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P5138/1:b..l
rcu: 	(detected by 1, t=10502 jiffies, g=89945, q=260 ncpus=2)
task:udevd           state:R  running task     stack:23144 pid:5138  ppid:1      flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x15ae/0x4660 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_acquire+0x208/0x420 kernel/locking/lockdep.c:5758
Code: f7 84 24 80 00 00 00 00 02 00 00 43 c6 44 3c 04 f8 0f 85 f0 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 04 3c 00 00 00 00 43 c7 44 3c 08 00 00 00 00 65 48 8b 04 25
RSP: 0018:ffffc90003237480 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 74edbbb6aea75500
RDX: 0000000000000000 RSI: ffffffff8acadce0 RDI: ffffffff8b1c7be0
RBP: ffffc90003237590 R08: dffffc0000000000 R09: 1ffffffff22378a0
R10: dffffc0000000000 R11: fffffbfff22378a1 R12: 1ffff92000646e9c
R13: ffffffff8d131da0 R14: 0000000000000246 R15: dffffc0000000000
 rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
 rcu_read_lock include/linux/rcupdate.h:786 [inline]
 is_bpf_text_address+0x47/0x2a0 kernel/bpf/core.c:741
 kernel_text_address+0xa0/0xd0 kernel/extable.c:125
 __kernel_text_address+0xd/0x30 kernel/extable.c:79
 unwind_get_return_address+0x5d/0xc0 arch/x86/kernel/unwind_orc.c:369
 arch_stack_walk+0x11d/0x190 arch/x86/kernel/stacktrace.c:26
 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+0xb7/0x240 mm/slab_common.c:1020
 kmalloc include/linux/slab.h:604 [inline]
 kzalloc include/linux/slab.h:721 [inline]
 tomoyo_encode2 security/tomoyo/realpath.c:45 [inline]
 tomoyo_encode+0x2ad/0x570 security/tomoyo/realpath.c:80
 tomoyo_realpath_from_path+0x57c/0x5c0 security/tomoyo/realpath.c:283
 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: 0033:0x7f847e511ad7
RSP: 002b:00007fff1020eda8 EFLAGS: 00000202 ORIG_RAX: 0000000000000005
RAX: ffffffffffffffda RBX: 000000000000000f RCX: 00007f847e511ad7
RDX: 0000000000090800 RSI: 00007fff1020edb0 RDI: 000000000000000f
RBP: 00007fff1020edb0 R08: 0000000000000000 R09: 0000000000000001
R10: 0000000000000000 R11: 0000000000000202 R12: 0000563108d327b0
R13: 00000000000000fd R14: 00005630db14bbe0 R15: 00007fff1020f150
 </TASK>
rcu: rcu_preempt kthread starved for 10126 jiffies! g89945 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:26664 pid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x15ae/0x4660 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+0x30d/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: 0 Comm: swapper/1 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:pv_native_safe_halt+0xf/0x10 arch/x86/kernel/paravirt.c:148
Code: dc 23 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 43 67 44 00 fb f4 <c3> 66 0f 1f 00 55 41 57 41 56 41 54 53 50 8b 2f eb 2c 89 cb 80 f9
RSP: 0018:ffffc90000187de0 EFLAGS: 000002c6
RAX: 4203fc990323b900 RBX: ffffffff81628b01 RCX: 4203fc990323b900
RDX: 0000000000000001 RSI: ffffffff8acacb60 RDI: ffffffff8b1c7be0
RBP: ffffc90000187f20 R08: ffff8880b8f36bab R09: 1ffff110171e6d75
R10: dffffc0000000000 R11: ffffed10171e6d76 R12: 1ffff92000030fc8
R13: dffffc0000000000 R14: 1ffff110036cd780 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb53644218f CR3: 0000000022f5b000 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+0x221/0x5c0 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 (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/07/01 06:01 linux-6.6.y d1cfde2d5d15 00a5cf1c .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in sys_newfstat
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.