linux-kernel - Re: [PATCH] PM / hibernate: Introduce snapshot test mode for hibernation

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Message-ID: <CAJZ5v0hsero4EhCwjo2mz4tN4aHj=bhsgcVJUYjHF9Kem=6M6g@mail.gmail.com>
Date:	Wed, 13 Jul 2016 22:44:24 +0200
From:	"Rafael J. Wysocki" <rafael@...nel.org>
To:	Pavel Machek <pavel@....cz>
Cc:	"Rafael J. Wysocki" <rafael@...nel.org>,
	Chen Yu <yu.c.chen@...el.com>,
	Linux PM <linux-pm@...r.kernel.org>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Len Brown <len.brown@...el.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] PM / hibernate: Introduce snapshot test mode for hibernation

On Wed, Jul 13, 2016 at 10:26 PM, Pavel Machek <pavel@....cz> wrote:
> On Wed 2016-07-13 22:04:27, Rafael J. Wysocki wrote:
>> On Wed, Jul 13, 2016 at 7:01 PM, Pavel Machek <pavel@....cz> wrote:
>> > Hi!
>> >
>> >> >>and then swapon the swap device, and do a testing. This should be safer?
>> >> >Yeah, that's the way. Read-only root is other option.
>> >> >
>> >> >>>I guess updating documentation would be welcome from my side,
>> >> >>>otherwise it should be ok.
>> >> >>OK, I'll  update the documents.
>> >> >Just add fat warning into the documentation.
>> >> OK.
>> >
>> > Actually... If you could add
>> >
>> > printk(KERN_ALERT "Hibernation image written. If you have any
>> > filesystems mounted read-write and attempt to resume, you'll corrupt
>> > your data. To prevent that, remove the hibernation image.\n")
>> >
>> > ...I guess that would save someone's filesystem. (Yes, very high
>> > loglevel. If you attempt to do this from anything else then singleuser
>> > or initrd, you are asking for problems, so... lets make sure user sees
>> > it.)
>>
>> Please see the new version of this patch:
>> https://patchwork.kernel.org/patch/9226837/
>
> New version changes nothing, right? You still need to be sure
> filesystems are not mounted r/w. So I would still like to see printk()
> with warning.

It shouldn't matter how they are mounted, because the contents of
persistent storage don't change.

Thanks,
Rafael