rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P6104/1:b..l
rcu: (detected by 0, t=10502 jiffies, g=9621, q=188 ncpus=2)
task:udevd state:R running task stack:27112 pid:6104 tgid:6104 ppid:5189 task_flags:0x400140 flags:0x00080000
Call Trace:
context_switch kernel/sched/core.c:5256 [inline]
__schedule+0x1139/0x6150 kernel/sched/core.c:6863
preempt_schedule_common+0x44/0xc0 kernel/sched/core.c:7047
preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12
__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
_raw_spin_unlock_irqrestore+0x61/0x80 kernel/locking/spinlock.c:194
sock_def_readable+0x15b/0x5d0 net/core/sock.c:3611
unix_dgram_sendmsg+0xcbd/0x1830 net/unix/af_unix.c:2286
sock_sendmsg_nosec net/socket.c:727 [inline]
__sock_sendmsg net/socket.c:742 [inline]
sock_write_iter+0x566/0x610 net/socket.c:1195
new_sync_write fs/read_write.c:593 [inline]
vfs_write+0x7d3/0x11d0 fs/read_write.c:686
ksys_write+0x1f8/0x250 fs/read_write.c:738
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xcd/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f0a1caa7407
RSP: 002b:00007ffe96807ef0 EFLAGS: 00000202 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f0a1d1c0880 RCX: 00007f0a1caa7407
RDX: 0000000000000000 RSI: 00007ffe96807f97 RDI: 000000000000000a
RBP: 000000000000000a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 00007f0a1d1c06e8
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
rcu: rcu_preempt kthread starved for 10522 jiffies! g9621 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:28024 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000
Call Trace:
context_switch kernel/sched/core.c:5256 [inline]
__schedule+0x1139/0x6150 kernel/sched/core.c:6863
__schedule_loop kernel/sched/core.c:6945 [inline]
schedule+0xe7/0x3a0 kernel/sched/core.c:6960
schedule_timeout+0x123/0x290 kernel/time/sleep_timeout.c:99
rcu_gp_fqs_loop+0x1ea/0xaf0 kernel/rcu/tree.c:2083
rcu_gp_kthread+0x26d/0x380 kernel/rcu/tree.c:2285
kthread+0x3c5/0x780 kernel/kthread.c:463
ret_from_fork+0x983/0xb10 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 6109 Comm: syz.4.31 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:check_kcov_mode kernel/kcov.c:185 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x3b/0x70 kernel/kcov.c:217
Code: 8b 05 a9 c9 f3 11 a9 00 01 ff 00 74 1d f6 c4 01 74 43 a9 00 00 0f 00 75 3c a9 00 00 f0 00 75 35 8b 82 6c 16 00 00 85 c0 74 2b <8b> 82 48 16 00 00 83 f8 02 75 20 48 8b 8a 50 16 00 00 8b 92 4c 16
RSP: 0018:ffffc90002ff7cd8 EFLAGS: 00040246
RAX: 0000000080000000 RBX: ffffc90002ff7f48 RCX: ffffffff815e93b3
RDX: ffff8880206c4980 RSI: ffffffff815e964d RDI: ffffc90002ff7fa0
RBP: 00007fffec7e1eb8 R08: 0000000000000006 R09: 00007ffffffff000
R10: 00007fffec7e1eb8 R11: ffff8880206c54b0 R12: ffffc90002ff7df8
R13: ffff8880206c4980 R14: ffffc90002ff7e00 R15: ffff8880206c52f0
FS: 0000555587e0f500(0000) GS:ffff8881249f5000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000556f4969de50 CR3: 000000002fcbc000 CR4: 00000000003526f0
Call Trace:
__unsafe_setup_sigcontext arch/x86/kernel/signal_64.c:110 [inline]
x64_setup_rt_frame+0x46d/0xcf0 arch/x86/kernel/signal_64.c:189
setup_rt_frame arch/x86/kernel/signal.c:250 [inline]
handle_signal arch/x86/kernel/signal.c:294 [inline]
arch_do_signal_or_restart+0x5da/0x7e0 arch/x86/kernel/signal.c:339
__exit_to_user_mode_loop kernel/entry/common.c:41 [inline]
exit_to_user_mode_loop+0x8c/0x540 kernel/entry/common.c:75
__exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline]
do_syscall_64+0x4ee/0xf80 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f08c018f749
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fffec7e2ba8 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 00007f08c03e5fa0 RCX: 00007f08c018f749
RDX: 0000200000000240 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f08c0213f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f08c03e5fa0 R14: 00007f08c03e5fa0 R15: 0000000000000004