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




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