rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	(detected by 0, t=10502 jiffies, g=18845, q=338 ncpus=2)
rcu: All QSes seen, last rcu_preempt kthread activity 10502 (4294961657-4294951155), jiffies_till_next_fqs=1, root ->qsmask 0x0
rcu: rcu_preempt kthread starved for 10502 jiffies! g18845 f0x2 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:27680 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5290 [inline]
 __schedule+0x14db/0x5030 kernel/sched/core.c:6902
 __schedule_loop kernel/sched/core.c:6984 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:6999
 schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x301/0x11b0 kernel/rcu/tree.c:2095
 rcu_gp_kthread+0x9b/0x2d0 kernel/rcu/tree.c:2297
 kthread+0x389/0x480 kernel/kthread.c:467
 ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </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 UID: 0 PID: 6460 Comm: syz.0.21 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:constant_test_bit arch/x86/include/asm/bitops.h:202 [inline]
RIP: 0010:arch_test_bit arch/x86/include/asm/bitops.h:232 [inline]
RIP: 0010:_test_bit include/asm-generic/bitops/instrumented-non-atomic.h:142 [inline]
RIP: 0010:test_ti_thread_flag include/linux/thread_info.h:131 [inline]
RIP: 0010:restore_fpregs_from_user arch/x86/kernel/fpu/signal.c:-1 [inline]
RIP: 0010:__fpu_restore_sig arch/x86/kernel/fpu/signal.c:346 [inline]
RIP: 0010:fpu__restore_sig+0x62e/0x10d0 arch/x86/kernel/fpu/signal.c:480
Code: 00 00 4c 8b 24 24 41 ff 8c 24 ac 17 00 00 31 ff 44 89 ee e8 44 ed 56 00 4c 89 e7 be 08 00 00 00 e8 97 c0 bd 00 48 8b 44 24 50 <42> 80 3c 30 00 74 08 4c 89 e7 e8 13 be bd 00 4d 8b 24 24 41 81 e4
RSP: 0018:ffffc90003ccfae0 EFLAGS: 00000256
RAX: 1ffff110046ea000 RBX: ffff888023751990 RCX: ffffffff816a80a9
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffff888023750000
RBP: ffffc90003ccfc90 R08: ffff888023750007 R09: 1ffff110046ea000
R10: dffffc0000000000 R11: ffffed10046ea001 R12: ffff888023750000
R13: 0000000000000000 R14: dffffc0000000000 R15: 00007f0fa6bb8d00
FS:  00007f0fa6bb96c0(0000) GS:ffff888125aad000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f4395f36440 CR3: 0000000030c32000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 restore_sigcontext arch/x86/kernel/signal_64.c:95 [inline]
 __ia32_sys_rt_sigreturn+0x704/0x860 arch/x86/kernel/signal_64.c:268
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f0fa5d8f747
Code: ff ff 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
RSP: 002b:00007f0fa6bb90e8 EFLAGS: 00000246
RAX: 00000000000000ca RBX: 00007f0fa5fe5fa8 RCX: 00007f0fa5d8f749
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f0fa5fe5fa8
RBP: 00007f0fa5fe5fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f0fa5fe6038 R14: 00007fffd6c6e920 R15: 00007fffd6c6ea08
 </TASK>