syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	(detected by 0, t=10502 jiffies, g=8089, q=46 ncpus=2)
rcu: All QSes seen, last rcu_preempt kthread activity 10502 (4294955534-4294945032), jiffies_till_next_fqs=1, root ->qsmask 0x0
rcu: rcu_preempt kthread starved for 10502 jiffies! g8089 f0x2 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
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:27752 pid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5380 [inline]
 __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
 schedule+0xbd/0x170 kernel/sched/core.c:6773
 schedule_timeout+0x160/0x280 kernel/time/timer.c:2167
 rcu_gp_fqs_loop+0x302/0x1560 kernel/rcu/tree.c:1667
 rcu_gp_kthread+0x99/0x380 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: 0 PID: 5819 Comm: syz-executor155 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:lock_acquire+0x1f2/0x410 kernel/locking/lockdep.c:5758
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 04 3c 00 00 00 00 66 43 c7 44 3c 09 00 00 43 c6 44 3c 0b 00
RSP: 0018:ffffc900045bfae0 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 5ea55f4cb735b600
RDX: 0000000000000000 RSI: ffffffff8aaace60 RDI: ffffffff8afc6f40
RBP: ffffc900045bfbf0 R08: dffffc0000000000 R09: 1ffffffff21b52a6
R10: dffffc0000000000 R11: fffffbfff21b52a7 R12: 1ffff920008b7f68
R13: ffff88801bbc14a0 R14: 0000000000000246 R15: dffffc0000000000
FS:  00005555665e73c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f09eed1cbe0 CR3: 000000002378c000 CR4: 00000000003506f0
Call Trace:
 <TASK>
 __might_fault+0xc6/0x120 mm/memory.c:5968
 rseq_get_rseq_cs_ptr_val kernel/rseq.c:161 [inline]
 rseq_get_rseq_cs kernel/rseq.c:183 [inline]
 rseq_ip_fixup kernel/rseq.c:303 [inline]
 __rseq_handle_notify_resume+0x12e/0x1170 kernel/rseq.c:351
 rseq_handle_notify_resume include/linux/sched.h:2364 [inline]
 rseq_signal_deliver include/linux/sched.h:2372 [inline]
 setup_rt_frame arch/x86/kernel/signal.c:212 [inline]
 handle_signal arch/x86/kernel/signal.c:267 [inline]
 arch_do_signal_or_restart+0x3bb/0x7b0 arch/x86/kernel/signal.c:312
 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
 exit_to_user_mode_prepare+0xf6/0x180 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302
 do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:87
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f09eed05289
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 1b 00 00 90 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffcc7241808 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 0000000000000003 RCX: 00007f09eed05289
RDX: 000020000006b000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 00007f09eecbd990 R09: 00007f09eecbd990
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f09eed55188
R13: 00007f09eed5bebc R14: 00007ffcc7241840 R15: 0000000000000000
 </TASK>