From: tomli@tomli.me
To: "Aaro Koskinen" <aaro.koskinen@iki.fi>,
"Paul E. McKenney" <paulmck@linux.ibm.com>,
"Rafael J. Wysocki" <rafael@kernel.org>,
"Ville Syrjälä" <ville.syrjala@linux.intel.com>
Cc: ak@linux.intel.com, bp@alien8.de, hpa@zytor.com,
linux-kernel@vger.kernel.org, mingo@redhat.com,
rjw@rjwysocki.net, viresh.kumar@linaro.org,
linux-mips@vger.kernel.org
Subject: Re: [REGRESSION 4.20-rc1] 45975c7d21a1 ("rcu: Define RCU-sched API in terms of RCU for Tree RCU PREEMPT builds")
Date: Wed, 6 Feb 2019 09:22:14 +0800 [thread overview]
Message-ID: <20190206012214.GA25642@x220> (raw)
In-Reply-To: <20190205185914.GB16356@darkstar.musicnaut.iki.fi>
> OK, thanks. This looks slightly different from the Loongson problem:
>
> - In Loongson, we don't get stuck in RCU, but in
> cpufreq_dbs_governor_stop -> irq_work_sync().
>
> - I run non-preemptible kernel, and my system still gets stuck.
>
> What is common is that it's UP with i8259 PIC.
>
> A.
Now it's an interesting case. Because on my machine, the problem I
encountered seems to be the identical one of the original thread,
disabling preempting can effectively solve the lockup. Also, my
issue is not only occuring on 4.20-rc1, but also on earlier kernels,
with a lower probability.
But on your machine, you have another non-identical, but closely-
related issue. It seems the timing-dependent lockup of i8259 PIC can
be triggered in different ways.
The conclusion is clear though, there's a real lockup condition in
i8259 PIC driver, and it's causing real issues. Aaro, have you tried
submitting your i8259 patch to the mainline? Despite your concerns
about its underlying cause, I think a fix should be submitted. If there
are no objections from the maintainers, I suggest submitting it to the
mainline upstream, and send it to linux-stable, requesting it to be
applied on 3.16, 4.4, 4.9, 4.14, 4.19, 4.20 stable branches. If you
are busy, I can help submitting.
Tom Li
prev parent reply other threads:[~2019-02-06 1:22 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20181113135453.GW9144@intel.com>
[not found] ` <20181113151037.GG4170@linux.ibm.com>
[not found] ` <20181114202013.GA27603@linux.ibm.com>
[not found] ` <20181126220122.GA6345@linux.ibm.com>
2019-02-05 5:07 ` [REGRESSION 4.20-rc1] 45975c7d21a1 ("rcu: Define RCU-sched API in terms of RCU for Tree RCU PREEMPT builds") Tom Li
2019-02-05 9:58 ` Aaro Koskinen
2019-02-05 13:05 ` Tom Li
2019-02-05 18:59 ` Aaro Koskinen
2019-02-06 1:22 ` tomli [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190206012214.GA25642@x220 \
--to=tomli@tomli.me \
--cc=aaro.koskinen@iki.fi \
--cc=ak@linux.intel.com \
--cc=bp@alien8.de \
--cc=hpa@zytor.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mips@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=paulmck@linux.ibm.com \
--cc=rafael@kernel.org \
--cc=rjw@rjwysocki.net \
--cc=ville.syrjala@linux.intel.com \
--cc=viresh.kumar@linaro.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).