FYI, we noticed the following commit:

commit: 867786e506615777d96589532760026ee995e830 ("rcu: Use for_each_leaf_node_cpu() in force_qs_rnp()")
https://github.com/fbq/linux.git leaf-node

in testcase: boot

on test machine: qemu-system-x86_64 -enable-kvm -cpu host -smp 2 -m 2G

caused below changes:


+------------------------------------------------+------------+------------+
|                                                | b024ae3068 | 867786e506 |
+------------------------------------------------+------------+------------+
| boot_successes                                 | 30         | 11         |
| boot_failures                                  | 0          | 21         |
| BUG:kernel_hang_in_test_stage                  | 0          | 2          |
| INFO:rcu_preempt_detected_stalls_on_CPUs/tasks | 0          | 19         |
| calltrace:populate_rootfs                      | 0          | 19         |
| calltrace:SyS_write                            | 0          | 5          |
| calltrace:SyS_open                             | 0          | 2          |
| calltrace:SyS_mkdir                            | 0          | 1          |
| calltrace:SyS_newlstat                         | 0          | 1          |
+------------------------------------------------+------------+------------+



[   13.248262] pci 0000:00:02.0: Video device with shadowed ROM at [mem 0x000c0000-0x000dffff]
[   13.268999] PCI: CLS 0 bytes, default 64
[   13.280821] Unpacking initramfs...
[  117.229392] INFO: rcu_preempt detected stalls on CPUs/tasks:
[  117.289959] All QSes seen, last rcu_preempt kthread activity 2 (4294948278-4294948276), jiffies_till_next_fqs=1, root ->qsmask 0x2
[  117.312450] swapper/0       R  running task        0     1      0 0x00080000
[  117.331767]  ffff880077403ee0 ffffffffa42f6494 ffffffffa5052540 ffff880077417940
[  117.352989]  ffff880077403f60 ffffffffa43214aa 0000000000000002 ffff880077403f18
[  117.369357]  ffff88007481ab40 ffffffffa437b7e6 ffffffffffffff66 0000000077403f28
[  117.388704] Call Trace:
[  117.396733]  <IRQ> 
[  117.401563]  [<ffffffffa42f6494>] sched_show_task+0xc9/0xce
[  117.417968]  [<ffffffffa43214aa>] rcu_check_callbacks+0x633/0x7db
[  117.432872]  [<ffffffffa437b7e6>] ? irq_trace+0x32/0x37
[  117.445762]  [<ffffffffa43271d1>] update_process_times+0x35/0x64
[  117.460312]  [<ffffffffa4338d32>] tick_nohz_handler+0xf6/0x15c
[  117.474251]  [<ffffffffa423b2f0>] local_apic_timer_interrupt+0x4b/0x4e
[  117.487864]  [<ffffffffa4ab0a64>] smp_apic_timer_interrupt+0x2e/0x3e
[  117.501506]  [<ffffffffa4ab0001>] apic_timer_interrupt+0x91/0xa0
[  117.510415]  <EOI> 
[  117.513338]  [<ffffffffa471cbda>] ? simple_strtoull+0x61/0x61
[  117.527140]  [<ffffffffa51f33d4>] ? parse_header+0x37/0xe9
[  117.540004]  [<ffffffffa4402b99>] ? ___cache_free+0x245/0x2a9
[  117.553745]  [<ffffffffa4401d79>] ? compound_head+0x2b/0x3c
[  117.565148]  [<ffffffffa437b7e6>] ? irq_trace+0x32/0x37
[  117.578048]  [<ffffffffa51f3593>] do_header+0x89/0x1cc
[  117.588672]  [<ffffffffa51f2f82>] write_buffer+0x32/0x4a
[  117.597037]  [<ffffffffa51f2fd4>] flush_buffer+0x3a/0xcc
[  117.606495]  [<ffffffffa51f2e94>] ? initrd_load+0x4e/0x4e
[  117.616870]  [<ffffffffa523290f>] __gunzip+0x38d/0x44c
[  117.627537]  [<ffffffffa5232573>] ? bunzip2+0x4df/0x4df
[  117.635832]  [<ffffffffa51f2f9a>] ? write_buffer+0x4a/0x4a
[  117.646073]  [<ffffffffa52329ce>] ? __gunzip+0x44c/0x44c
[  117.655664]  [<ffffffffa5232a18>] gunzip+0x4a/0x4c
[  117.666128]  [<ffffffffa51f2e94>] ? initrd_load+0x4e/0x4e
[  117.678963]  [<ffffffffa51f2f9a>] ? write_buffer+0x4a/0x4a
[  117.692345]  [<ffffffffa51f3910>] unpack_to_rootfs+0x1da/0x339
[  117.706340]  [<ffffffffa51f2e94>] ? initrd_load+0x4e/0x4e
[  117.719276]  [<ffffffffa51f3bc7>] ? maybe_link+0x158/0x158
[  117.733437]  [<ffffffffa51f18fd>] ? set_debug_rodata+0x20/0x20
[  117.747078]  [<ffffffffa51f3c3a>] populate_rootfs+0x73/0xdf
[  117.758969]  [<ffffffffa51f3bc7>] ? maybe_link+0x158/0x158
[  117.772448]  [<ffffffffa420050a>] do_one_initcall+0xa7/0x18d
[  117.782438]  [<ffffffffa51f18fd>] ? set_debug_rodata+0x20/0x20
[  117.795624]  [<ffffffffa51f2425>] kernel_init_freeable+0x1c5/0x270
[  117.808457]  [<ffffffffa4aa8065>] ? rest_init+0x8c/0x8c
[  117.820931]  [<ffffffffa4aa8079>] kernel_init+0x14/0x14c
[  117.832116]  [<ffffffffa4aa8065>] ? rest_init+0x8c/0x8c
[  117.844525]  [<ffffffffa4aae92a>] ret_from_fork+0x2a/0x40
[  140.516967] Freeing initrd memory: 140196K (ffff8800776e7000 - ffff88007ffd0000)
[  140.572471] Scanning for low memory corruption every 60 seconds
[  140.645128] AVX or AES-NI instructions are not detected.


To reproduce:

        git clone git://git.kernel.org/pub/scm/linux/kernel/git/wfg/lkp-tests.git
        cd lkp-tests
        bin/lkp qemu -k <bzImage> job-script  # job-script is attached in this email



Thanks,
Ying Huang