linux-kernel - Re: [SUSPECTED SPAM] Re: [linux-pm] Proposal for a new algorithm for reading & writing a hibernation image.

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <1275698720.10045.15.camel@maxim-laptop>
Date:	Sat, 05 Jun 2010 03:45:20 +0300
From:	Maxim Levitsky <maximlevitsky@...il.com>
To:	Nigel Cunningham <ncunningham@...a.org.au>
Cc:	Pavel Machek <pavel@....cz>,
	pm list <linux-pm@...ts.linux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>,
	TuxOnIce-devel <tuxonice-devel@...onice.net>
Subject: Re: [SUSPECTED SPAM] Re: [linux-pm] Proposal for a new algorithm
 for reading & writing a hibernation image.

On Sat, 2010-06-05 at 03:36 +0300, Maxim Levitsky wrote: 
> On Sat, 2010-06-05 at 09:58 +1000, Nigel Cunningham wrote: 
> > Hi Maxim.
> > 
> > On 05/06/10 09:39, Maxim Levitsky wrote:
> > > On Thu, 2010-06-03 at 16:50 +0200, Pavel Machek wrote:
> > >>
> > >> "Nigel Cunningham"<ncunningham@...a.org.au>  wrote:
> > >>
> > >>> Hi.
> > >>>
> > >>> On 30/05/10 15:25, Pavel Machek wrote:
> > >>>> Hi!
> > >>>>
> > >>>>> 2. Prior to writing any of the image, also set up new 4k page tables
> > >>>>> such that an attempt to make a change to any of the pages we're about to
> > >>>>> write to disk will result in a page fault, giving us an opportunity to
> > >>>>> flag the page as needing an atomic copy later. Once this is done, write
> > >>>>> protection for the page can be disabled and the write that caused the
> > >>>>> fault allowed to proceed.
> > >>>>
> > >>>> Tricky.
> > >>>>
> > >>>> page faulting code touches memory, too...
> > >>>
> > >>> Yeah. I realise we'd need to make the pages that are used to record the
> > >>> faults be unprotected themselves. I'm imagining a bitmap for that.
> > >>>
> > >>> Do you see any reason that it could be inherently impossible? That's
> > >>> what I really want to know before (potentially) wasting time trying it.
> > >>
> > >> I'm not sure it is impossible, but it certainly seems way too complex to be
> > >> practical.
> > >>
> > >> 2mb pages will probably present a problem, as will bat mappings on powerpc.
> > >
> > >
> > > Some time ago, after tuxonce caused medium fs corruption twice on my
> > > root filesystem (superblock gone for example), I was thinking too about
> > > how to make it safe to save whole memory.
> > 
> > I'd be asking why you got the corruption. On the odd occasion where it 
> > has been reported, it's usually been because the person didn't set up 
> > their initramfs correctly (resumed after mounting filesystems). Is there 
> > any chance that you did that?
I didn't use any initramfs.
I did use kernel modesetting and nouveau.
I used ext4.
The corruption happened after normal suspend.
I replaces swsusp with tuxonice.

Anyway, some more or less verified method must be used to save memory
because fs corruption is too scary thing to have.

I can't say it scared me that much 'cause I had dealt with worse
corruptions before, but being thrown to  "grub rescue>" on boot is not
pleasant thing to see.

Best regards,
Maxim Levitsky


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/