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    SubjectRe: MMC/SD Root filesystem suspend/resume problems

    > > > Lots of Linux handhelds use MMC/SD devices as the root file system.
    > > > This has worked quite reliably for many kernel versions. In 2.6.22,
    > > > it seems that if you suspend such a system then resume it, the device
    > > > locks up. Trying to execute anything on the filesystem results in a
    > > > "Permission Denied" message. I did see a message from the MMC
    > > > subsystem saying it had redetected the card. There are also messages
    > > > on the console like "MMC: killing requests for dead queue" each time
    > > > you suspend/resume.
    > >
    > > The card is removed when you suspend and readded when you resume.
    > > That's the only safe thing we can do until we get suspend support in
    > > the filesystems.
    > >
    > > If you really want to shoot yourself in the foot, there is a Kconfig
    > > option that keeps the card around across the suspend.
    > I enabled the MMC_UNSAFE_RESUME option and the problems I was seeing was
    > "fixed". I think having this option is a bad idea (in its current form)
    > as it doesn't actually stop filesystem corruption.
    > With the option disabled, if a filesystem is mounted when you suspend my
    > tests show the filesystem is corrupted. At least if the option is
    > enabled, the filesystem is only corrupted if you remove the card whilst
    > suspended which is more preferable.

    Are we talking _corruption_ here, or are we talking 'the kind of
    corruption recoverable by fsck that happens on powerfail'?


    (cesky, pictures)
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