Re: [linux-pm] Is it supposed to be ok to call del_gendisk whileuserspace is frozen?

From: Alan Stern
Date: Mon Mar 01 2010 - 10:23:33 EST

On Mon, 1 Mar 2010, Pavel Machek wrote:

> Hi!
> > > > This is a matter for Jens. Is the bdi writeback task freezable? If it
> > > > is, should it be made unfreezable?
> > >
> > > I'm not a big expect on what tasks should be freezable or not. As it
> > > stands, the writeback tasks will attempt to freeze and thaw with the
> > > system. I guess that screws the sync from resume call, since it's not
> > > running and the sync will wait for it to retrieve and finish that work
> > > item.
> > >
> > > To the suspend experts - can we safely mark the writeback tasks as
> > > non-freezable?
> >
> > The reason for freezing those tasks is to avoid writebacks at random
> > times during a system sleep transition, when the underlying device may
> > already be suspended, right?
> It is also there to avoid inconsistency between in-filesystem data and
> snapshot in hibernation image.

A good point, although in this case I think it won't matter. Writing
out a dirty page twice (once right after taking the snapshot and then
again after resuming from hibernation) will leave the disk in a correct

Alan Stern

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