rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	(detected by 1, t=10002 jiffies, g=1253, q=404 ncpus=2)
rcu: All QSes seen, last rcu_preempt kthread activity 10002 (4294952521-4294942519), jiffies_till_next_fqs=1, root ->qsmask 0x0
rcu: rcu_preempt kthread starved for 10002 jiffies! g1253 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:0     pid:18    tgid:18    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5945 [inline]
 __schedule+0x1322/0x1df0 kernel/sched/core.c:7791
 __schedule_loop kernel/sched/core.c:7872 [inline]
 schedule+0xc6/0x240 kernel/sched/core.c:7887
 schedule_timeout+0x139/0x3a0 kernel/time/timer.c:2619
 rcu_gp_fqs_loop+0x2f2/0x12f0 kernel/rcu/tree.c:2053
 rcu_gp_kthread+0x99/0x380 kernel/rcu/tree.c:2255
 kthread+0x2ca/0x370 kernel/kthread.c:389
 ret_from_fork+0x67/0xa0 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 1 UID: 0 PID: 799 Comm: syz.0.128 Not tainted syzkaller #0 68071847e78a8b5e73ab1b858b320f4e6b4f981b
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:__sanitizer_cov_trace_pc+0x8/0x70 kernel/kcov.c:213
Code: 52 00 5b 5d c3 cc cc cc cc cc cc cc cc cc cc cc cc cc b8 97 86 b1 cc 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 55 48 89 e5 <48> 8b 45 08 65 48 8b 0c 25 00 eb 04 00 65 8b 15 ec ea 7e 7e 81 e2
RSP: 0018:ffffc9000df479b0 EFLAGS: 00000206
RAX: 1ffff1102707f39b RBX: ffffffffffffff28 RCX: dffffc0000000000
RDX: ffffc90001651000 RSI: 000000000007ffff RDI: 0000000000080000
RBP: ffffc9000df479b0 R08: ffff888123ab59af R09: 0000000000000000
R10: ffff888123ab59a0 R11: ffffed1024756b36 R12: ffff8881383f8a80
R13: ffff88811189aaa0 R14: ffff8881383f9c20 R15: ffff88813776ddc0
FS:  00007f62faecc6c0(0000) GS:ffff8881f6f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f12b4de7dac CR3: 000000013b574000 CR4: 00000000003526b0
Call Trace:
 <TASK>
 do_make_slave fs/pnode.c:100 [inline]
 change_mnt_propagation+0x14a/0xb00 fs/pnode.c:128
 umount_tree+0xdfd/0xf70 fs/namespace.c:1803
 attach_recursive_mnt+0x6df/0x21e0 fs/namespace.c:2549
 graft_tree+0x157/0x1c0 fs/namespace.c:2684
 do_loopback+0x364/0x4b0 fs/namespace.c:2816
 path_mount+0x582/0x1050 fs/namespace.c:3858
 do_mount fs/namespace.c:3877 [inline]
 __do_sys_mount fs/namespace.c:4087 [inline]
 __se_sys_mount+0x2bd/0x480 fs/namespace.c:4064
 __x64_sys_mount+0xc3/0xf0 fs/namespace.c:4064
 x64_sys_call+0x2021/0x2ee0 arch/x86/include/generated/asm/syscalls_64.h:166
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x58/0xf0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7f62f9f8eec9
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:00007f62faecc038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f62fa1e5fa0 RCX: 00007f62f9f8eec9
RDX: 0000000000000000 RSI: 0000200000000200 RDI: 00002000000002c0
RBP: 00007f62fa011f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000101091 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f62fa1e6038 R14: 00007f62fa1e5fa0 R15: 00007fff2ef7f5b8
 </TASK>