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From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Young <dyoung@redhat.com>,
	bhe@redhat.com, Eric Biederman <ebiederm@xmission.com>,
	linux-kernel@vger.kernel.org, kexec@lists.infradead.org,
	Eric DeVolder <eric.devolder@oracle.com>,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>
Subject: Re: [PATCH] Only allow to set crash_kexec_post_notifiers on boot time
Date: Mon, 21 Sep 2020 16:18:12 -0400	[thread overview]
Message-ID: <20200921201811.GB3437@char.us.oracle.com> (raw)
In-Reply-To: <20200918174743.0994c59f058451948837dcb6@linux-foundation.org>

On Fri, Sep 18, 2020 at 05:47:43PM -0700, Andrew Morton wrote:
> On Fri, 18 Sep 2020 11:25:46 +0800 Dave Young <dyoung@redhat.com> wrote:
> 
> > crash_kexec_post_notifiers enables running various panic notifier
> > before kdump kernel booting. This increases risks of kdump failure.
> > It is well documented in kernel-parameters.txt. We do not suggest
> > people to enable it together with kdump unless he/she is really sure.
> > This is also not suggested to be enabled by default when users are
> > not aware in distributions.
> > 
> > But unfortunately it is enabled by default in systemd, see below
> > discussions in a systemd report, we can not convince systemd to change
> > it:
> > https://github.com/systemd/systemd/issues/16661
> > 
> > Actually we have got reports about kdump kernel hangs in both s390x
> > and powerpcle cases caused by the systemd change,  also some x86 cases
> > could also be caused by the same (although that is in Hyper-V code
> > instead of systemd, that need to be addressed separately).

Perhaps it may be better to fix the issus on s390x and PowerPC as well?

> > 
> > Thus to avoid the auto enablement here just disable the param writable
> > permission in sysfs.
> > 
> 
> Well.  I don't think this is at all a desirable way of resolving a
> disagreement with the systemd developers
> 
> At the above github address I'm seeing "ryncsn added a commit to
> ryncsn/systemd that referenced this issue 9 days ago", "pstore: don't
> enable crash_kexec_post_notifiers by default".  So didn't that address
> the issue?

It does in systemd, but there is a strong interest in making this on by default.

  parent reply	other threads:[~2020-09-21 20:16 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-18  3:25 [PATCH] Only allow to set crash_kexec_post_notifiers on boot time Dave Young
2020-09-19  0:47 ` Andrew Morton
2020-09-19  7:26   ` Dave Young
2020-09-21 20:18   ` Konrad Rzeszutek Wilk [this message]
2020-09-22  1:45     ` Eric W. Biederman
2020-09-23  2:43       ` Dave Young
2020-09-23 15:48         ` Konrad Rzeszutek Wilk
2020-09-24 16:15           ` Michael Kelley
2020-09-24 16:25             ` Eric W. Biederman
2020-09-24 16:43               ` Michael Kelley
2020-09-24 17:16                 ` boris.ostrovsky
2020-09-25  3:05                   ` Dave Young
2020-09-25 14:56                     ` Konrad Rzeszutek Wilk
2020-09-27  2:51                       ` Dave Young
2020-09-29 13:36                       ` Philipp Rudo
2020-09-29 19:10                         ` boris.ostrovsky
2020-09-22 10:58     ` Philipp Rudo
2020-09-22 14:50       ` boris.ostrovsky
2020-09-22 17:04         ` Guilherme G. Piccoli
2020-09-23  2:25     ` Dave Young

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