linux-kernel - Re: [PATCH v3 6/6] freezer,sched: Rewrite core freezer logic

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Message-ID: <436fa401-e113-0393-f47a-ed23890364d7@linux.ibm.com>
Date:   Mon, 26 Sep 2022 12:55:21 +0200
From:   Christian Borntraeger <borntraeger@...ux.ibm.com>
To:     peterz@...radead.org
Cc:     bigeasy@...utronix.de, dietmar.eggemann@....com,
        ebiederm@...ssion.com, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org, mgorman@...e.de, mingo@...nel.org,
        oleg@...hat.com, rjw@...ysocki.net, rostedt@...dmis.org,
        tj@...nel.org, vincent.guittot@...aro.org, will@...nel.org,
        Marc Hartmayer <mhartmay@...ux.ibm.com>
Subject: Re: [PATCH v3 6/6] freezer,sched: Rewrite core freezer logic



Am 26.09.22 um 10:06 schrieb Christian Borntraeger:
> 
> 
> Am 23.09.22 um 09:53 schrieb Christian Borntraeger:
>> Am 23.09.22 um 09:21 schrieb Christian Borntraeger:
>>> Peter,
>>>
>>> as a heads-up. This commit (bisected and verified) triggers a
>>> regression in our KVM on s390x CI. The symptom is that a specific
>>> testcase (start a guest with next kernel and a poky ramdisk,
>>> then ssh via vsock into the guest and run the reboot command) now
>>> takes much longer (300 instead of 20 seconds). From a first look
>>> it seems that the sshd takes very long to end during shutdown
>>> but I have not looked into that yet.
>>> Any quick idea?
>>>
>>> Christian
>>
>> the sshd seems to hang in virtio-serial (not vsock).
> 
> FWIW, sshd does not seem to hang, instead it seems to busy loop in
> wait_port_writable calling into the scheduler over and over again.

-#define TASK_FREEZABLE                 0x00002000
+#define TASK_FREEZABLE                 0x00000000

"Fixes" the issue. Just have to find out which of users is responsible.