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INFO: rcu detected stall in sys_getpid (2)

Status: upstream: reported on 2025/12/02 23:35
Reported-by: syzbot+5f89bc7d03a2e4c6f442@syzkaller.appspotmail.com
First crash: 52d, last: 52d
▶ ▼ Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.6 INFO: rcu detected stall in sys_getpid origin:lts-only 1 C inconclusive 4 60d 139d 0/2 upstream: reported C repro on 2025/09/06 16:11
linux-5.15 INFO: rcu detected stall in sys_getpid 1 1 576d 576d 0/3 auto-obsoleted due to no activity on 2024/10/04 19:18
linux-6.1 INFO: rcu detected stall in sys_getpid 1 1 273d 273d 0/3 auto-obsoleted due to no activity on 2025/08/03 12:49
linux-5.15 INFO: rcu detected stall in sys_getpid (2) origin:lts-only 1 C error 14 16d 419d 0/3 upstream: reported C repro on 2024/11/30 21:19

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P6529/1:b..l P6559/1:b..l
	(detected by 1, t=10502 jiffies, g=31965, q=115 ncpus=2)
task:syz.5.519       state:R  running task     stack:27808 pid:6559  ppid:6024   flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x10ec/0x40b0 kernel/sched/core.c:6561
 preempt_schedule_irq+0xb1/0x150 kernel/sched/core.c:6873
 irqentry_exit+0x63/0x70 kernel/entry/common.c:439
 asm_sysvec_reschedule_ipi+0x16/0x20 arch/x86/include/asm/idtentry.h:696
RIP: 0010:lock_acquire+0x20f/0x490 kernel/locking/lockdep.c:5666
Code: 00 9c 8f 84 24 80 00 00 00 f6 84 24 81 00 00 00 02 0f 85 f5 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 44 3d 00 00 00 00 00 66 43 c7 44 3d 09 00 00 43 c6 44 3d 0b
RSP: 0018:ffffc90004e5f540 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 7158d9d8e21f2e00
RDX: 0000000000000000 RSI: ffffffff8a8c1700 RDI: ffffffff8adef760
RBP: ffffc90004e5f658 R08: dffffc0000000000 R09: fffffbfff215c449
R10: fffffbfff215c449 R11: 1ffffffff215c448 R12: 0000000000000000
R13: 1ffff920009cbeb4 R14: 0000000000000246 R15: dffffc0000000000
 rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 rcu_read_lock include/linux/rcupdate.h:791 [inline]
 is_bpf_text_address+0x43/0x2a0 kernel/bpf/core.c:735
 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+0x98/0xe0 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:52
 kasan_save_free_info+0x2d/0x50 mm/kasan/generic.c:516
 ____kasan_slab_free+0x126/0x1e0 mm/kasan/common.c:236
 kasan_slab_free include/linux/kasan.h:177 [inline]
 slab_free_hook mm/slub.c:1729 [inline]
 slab_free_freelist_hook+0x131/0x1a0 mm/slub.c:1755
 slab_free mm/slub.c:3687 [inline]
 __kmem_cache_free+0xb6/0x1f0 mm/slub.c:3700
 skb_free_head net/core/skbuff.c:762 [inline]
 skb_release_data+0x5db/0x7c0 net/core/skbuff.c:791
 skb_release_all net/core/skbuff.c:856 [inline]
 __kfree_skb net/core/skbuff.c:870 [inline]
 kfree_skb_reason+0x163/0x370 net/core/skbuff.c:893
 kfree_skb include/linux/skbuff.h:1220 [inline]
 unix_release_sock+0xb2f/0xee0 net/unix/af_unix.c:646
 unix_release+0x88/0xc0 net/unix/af_unix.c:1032
 __sock_release net/socket.c:654 [inline]
 sock_close+0xd5/0x240 net/socket.c:1400
 __fput+0x22c/0x920 fs/file_table.c:320
 task_work_run+0x1ca/0x250 kernel/task_work.c:203
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:177
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:87
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fd685d8f749
RSP: 002b:00007fd686bdf038 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007fd685fe6180 RCX: 00007fd685d8f749
RDX: 0000000000000000 RSI: 0000000000000008 RDI: 0000000000000006
RBP: 00007fd685e13f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd685fe6218 R14: 00007fd685fe6180 R15: 00007ffeb7c37768
 </TASK>
task:syz.2.513       state:R  running task     stack:26240 pid:6529  ppid:4269   flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x10ec/0x40b0 kernel/sched/core.c:6561
 preempt_schedule_irq+0xb1/0x150 kernel/sched/core.c:6873
 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:pid_nr_ns kernel/pid.c:477 [inline]
RIP: 0010:__task_pid_nr_ns+0x227/0x460 kernel/pid.c:500
Code: 00 e8 8d de 2b 00 eb 05 e8 86 de 2b 00 4d 85 f6 74 5a 48 85 db 74 55 4d 8d be 80 00 00 00 4c 89 f8 48 c1 e8 03 42 0f b6 04 28 <84> c0 0f 85 ba 01 00 00 45 8b 3f 4c 8d 63 04 4c 89 e0 48 c1 e8 03
RSP: 0018:ffffc900050bfed8 EFLAGS: 00000a02
RAX: 0000000000000000 RBX: ffff88802ab23a00 RCX: ffff88807ded8000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: 0000000000000001 R08: dffffc0000000000 R09: fffffbfff215c449
R10: fffffbfff215c449 R11: 1ffffffff215c448 R12: 0000000000000001
R13: dffffc0000000000 R14: ffff88805ad98108 R15: ffff88805ad98188
 task_tgid_vnr include/linux/sched.h:1628 [inline]
 __ia32_sys_getpid+0x19/0x20 kernel/sys.c:953
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f5ccbd865e7
RSP: 002b:00007ffe79eb17c8 EFLAGS: 00000202 ORIG_RAX: 0000000000000027
RAX: ffffffffffffffda RBX: 00007ffe79eb1930 RCX: 00007f5ccbd865e7
RDX: 00007ffe79eb1800 RSI: 00007ffe79eb1930 RDI: 0000000000000021
RBP: 0000000000000000 R08: 00007f5ccbfe6038 R09: 00007f5ccbfd2000
R10: 00007f5ccb7ff008 R11: 0000000000000202 R12: 0000000000000005
R13: 0000000000000000 R14: ffffffff8171497b R15: 0000000000004c7f
 </TASK>
rcu: rcu_preempt kthread starved for 10520 jiffies! g31965 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->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:I stack:27840 pid:16    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x10ec/0x40b0 kernel/sched/core.c:6561
 preempt_schedule_common+0x82/0xd0 kernel/sched/core.c:6730
 preempt_schedule+0xa7/0xb0 kernel/sched/core.c:6754
 preempt_schedule_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:34
 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
 _raw_spin_unlock_irqrestore+0xf6/0x100 kernel/locking/spinlock.c:194
 debug_object_assert_init+0x1ed/0x2f0 lib/debugobjects.c:889
 debug_timer_assert_init kernel/time/timer.c:792 [inline]
 debug_assert_init kernel/time/timer.c:837 [inline]
 __mod_timer+0x54/0xd00 kernel/time/timer.c:1020
 schedule_timeout+0x157/0x280 kernel/time/timer.c:2166
 rcu_gp_fqs_loop+0x2f2/0x1310 kernel/rcu/tree.c:1706
 rcu_gp_kthread+0x95/0x380 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: 6557 Comm: syz.3.520 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:finish_task_switch+0x26a/0x8f0 kernel/sched/core.c:5123
Code: 0f 84 3b 01 00 00 48 85 db 0f 85 5a 01 00 00 e9 e8 04 00 00 4c 8b 75 d0 4c 89 e7 e8 e0 6d c9 08 e8 6b b7 2e 00 fb 4c 8b 65 c0 <49> 8d bc 24 f8 15 00 00 48 89 f8 48 c1 e8 03 42 0f b6 04 28 84 c0
RSP: 0018:ffffc90004fd7cd8 EFLAGS: 00000286
RAX: 59d914a5e7f87800 RBX: 0000000000000000 RCX: 59d914a5e7f87800
RDX: dffffc0000000000 RSI: ffffffff8a8c0580 RDI: ffffffff8adef760
RBP: ffffc90004fd7d30 R08: dffffc0000000000 R09: ffffed10171c7559
R10: ffffed10171c7559 R11: 1ffff110171c7558 R12: ffff88802e259dc0
R13: dffffc0000000000 R14: ffff888019340000 R15: ffff8880b8f3b590
FS:  000055557f8f1500(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f63757d8b30 CR3: 0000000078339000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5247 [inline]
 __schedule+0x10f4/0x40b0 kernel/sched/core.c:6561
 schedule+0xb9/0x180 kernel/sched/core.c:6637
 exit_to_user_mode_loop+0x47/0x110 kernel/entry/common.c:165
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
 irqentry_exit_to_user_mode+0x5/0x30 kernel/entry/common.c:316
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0033:0x7f637546ef9b
Code: 24 1e 01 45 31 ff 45 31 f6 44 0f b6 e6 85 c0 0f 84 9e 00 00 00 44 89 f9 49 8b 50 40 4c 89 f0 49 03 14 ca 80 3d 0d 8e 37 00 00 <49> 89 d6 48 89 d5 74 28 25 ff 0f 00 00 83 f0 3d 8d 04 c0 89 c5 c1
RSP: 002b:00007ffc28405860 EFLAGS: 00000202
RAX: ffffffff8183db7a RBX: 00007f6376315720 RCX: 0000000000022481
RDX: ffffffff8183dd37 RSI: ffffffff8183d7e6 RDI: 000000000000000e
RBP: ffffffff8183d7e6 R08: 00007f63757e6218 R09: 00007f63757d2000
R10: 00007f63747fb008 R11: 000000000000000e R12: 000000000000000e
R13: 0000000000000000 R14: ffffffff8183db7a R15: 0000000000022481
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/12/02 23:35 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_getpid
* Struck through repros no longer work on HEAD.