From:   Peng Fan <peng.fan@nxp.com>
To:     "mingo@redhat.com" <mingo@redhat.com>,
        "peterz@infradead.org" <peterz@infradead.org>,
        "juri.lelli@redhat.com" <juri.lelli@redhat.com>,
        "vincent.guittot@linaro.org" <vincent.guittot@linaro.org>,
        "dietmar.eggemann@arm.com" <dietmar.eggemann@arm.com>,
        "rostedt@goodmis.org" <rostedt@goodmis.org>,
        "bsegall@google.com" <bsegall@google.com>,
        "mgorman@suse.de" <mgorman@suse.de>,
        "bristot@redhat.com" <bristot@redhat.com>,
        "vschneid@redhat.com" <vschneid@redhat.com>,
        "tglx@linutronix.de" <tglx@linutronix.de>,
        "Rafael J. Wysocki" <rafael@kernel.org>
CC:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Jan Kiszka <jan.kiszka@siemens.com>
Subject: Fail to freeze process
Thread-Topic: Fail to freeze process
Thread-Index: AdlHUq0eJRhyCNK0Rb6CRNu6YQQwPQ==
Date:   Thu, 23 Feb 2023 06:49:31 +0000
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List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

Hi kernel experts,

I am facing a suspend/resume issue with linux on top of jailhouse hyperviso=
r on
ARM64 platform with 6.1 kernel.=20
Actually without enabling jailhouse hypervisor, the kernel suspend/resume w=
ell.
So it should be the jailhouse hypervisor introduce some interrupt/timer or =
else
bug cause this issue. But I have no idea for now what bug may introduce suc=
h
issue. So I wanna narrow and debug from linux side see why freeze time, the=
n
move into jailhouse hypervisor to fix it.

I have try to enlarge freeze time to 90s, still has similar issue, process =
freeze
failure, the issue not happen every time, but after a few round suspend/res=
ume,=20
it triggers. And the cpu running the process has a very large timer expirat=
ion value.
Even I use jtag to trigger the timer interrupt, the cpu runs into idle agai=
n.

I see the process has flag 0xa05, it has SIG Pending, but not sure why it c=
ould
not freeze.

Seems I have no idea to wakeup the cpu from idle and let it schedule.

Hope you have any ideas.

---- Running < /unit_tests/SRTC/rtcwakeup.out > test ----

rtcwakeup.[ 1153.430758] PM: suspend entry (deep)
out: wakeup from "mem" using rtc0[ 1153.435689] Filesystems sync: 0.000 sec=
onds
 at Fri Jan  2 00:20:51 1970
[ 1153.487507] Freezing user space processes ...
[ 1173.495070] Freezing of tasks failed after 20.003 seconds (1 tasks refus=
ing to freeze, wq_busy=3D0):
[ 1173.504091] task:systemd-userwor state:R stack:0     pid:1563  ppid:588 =
   flags:0x00000a05
[ 1173.512457] Call trace:
[ 1173.514909]  __switch_to+0xf0/0x170
[ 1173.518416]  __schedule+0x28c/0x710
[ 1173.521916]  schedule+0x5c/0xd0
[ 1173.525064]  schedule_timeout+0x8c/0x100
[ 1173.528996]  __skb_wait_for_more_packets+0x128/0x190
[ 1173.533975]  __skb_recv_datagram+0x80/0xe0
[ 1173.538081]  skb_recv_datagram+0x34/0x90
[ 1173.542014]  unix_accept+0xa0/0x1c0
[ 1173.545511]  do_accept+0x114/0x190
[ 1173.548916]  __sys_accept4+0x70/0xe4
[ 1173.552503]  __arm64_sys_accept4+0x20/0x30
[ 1173.556609]  invoke_syscall+0x48/0x114
[ 1173.560368]  el0_svc_common.constprop.0+0xcc/0xec
[ 1173.565085]  do_el0_svc+0x2c/0xd0
[ 1173.568412]  el0_svc+0x2c/0x84
[ 1173.571472]  el0t_64_sync_handler+0xf4/0x120
[ 1173.575752]  el0t_64_sync+0x18c/0x190
[ 1173.579434]
[ 1173.580947] OOM killer enabled.
[ 1173.584095] Restarting tasks ... done.
[ 1173.589831] random: crng reseeded on system resumption
[ 1173.595422] PM: suspend exit
write /sys/power/state: Device or resource busy
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D
suspend 57 times
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D

Thanks,
Peng.