syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	(detected by 0, t=10502 jiffies, g=7037, q=44 ncpus=2)
rcu: All QSes seen, last rcu_preempt kthread activity 10503 (4294955083-4294944580), jiffies_till_next_fqs=1, root ->qsmask 0x0
rcu: rcu_preempt kthread starved for 10504 jiffies! g7037 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:27656 pid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x1553/0x45a0 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+0x313/0x1590 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:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 5794 Comm: syz-executor368 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
RIP: 0010:__rb_insert lib/rbtree.c:94 [inline]
RIP: 0010:rb_insert_color+0x3f/0x670 lib/rbtree.c:436
Code: 49 89 fc 49 be 00 00 00 00 00 fc ff df 48 89 f8 48 c1 e8 03 42 80 3c 30 00 74 08 4c 89 e7 e8 e8 14 6b f7 49 8b 1c 24 48 85 db <0f> 84 06 06 00 00 4c 89 7c 24 10 eb 13 49 8b 1f 4d 89 fc 48 83 e3
RSP: 0018:ffffc90004b1fa40 EFLAGS: 00000086
RAX: 1ffff11005b6f816 RBX: ffff8880b8f2c050 RCX: ffff8880747f0000
RDX: 0000000000000000 RSI: ffff8880b8f2b7d0 RDI: ffff88802db7c0b0
RBP: ffff8880b8f2c001 R08: ffff88802db7c0c7 R09: 0000000000000000
R10: ffff88802db7c0b8 R11: ffffed1005b6f819 R12: ffff88802db7c0b0
R13: dffffc0000000000 R14: dffffc0000000000 R15: ffff8880b8f2b7d0
FS:  000055557f4763c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000140 CR3: 00000000745e9000 CR4: 00000000003506e0
Call Trace:
 <TASK>
 rb_insert_color_cached include/linux/rbtree.h:114 [inline]
 rb_add_cached include/linux/rbtree.h:183 [inline]
 timerqueue_add+0x1ca/0x1f0 lib/timerqueue.c:40
 enqueue_hrtimer+0x19b/0x370 kernel/time/hrtimer.c:1116
 __hrtimer_start_range_ns kernel/time/hrtimer.c:1290 [inline]
 hrtimer_start_range_ns+0xb4c/0xff0 kernel/time/hrtimer.c:1351
 posixtimer_rearm+0x135/0x340 kernel/time/posix-timers.c:268
 dequeue_signal+0x1ba/0x4b0 kernel/signal.c:706
 get_signal+0x551/0x13f0 kernel/signal.c:2782
 arch_do_signal_or_restart+0xc2/0x800 arch/x86/kernel/signal.c:310
 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
 exit_to_user_mode_prepare+0xee/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+0x61/0xa0 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fb746679449
Code: c0 79 93 eb d5 48 8d 7c 1d 00 eb 99 0f 1f 44 00 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 d0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffe1c478ca8 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 0000000000000003 RCX: 00007fb746679449
RDX: 000020000006b000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000200000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fb7466f70b2
R13: 00007fb7466f512a R14: 0000200000000148 R15: 0000000000000000
 </TASK>