Re: [linux-pm] Is it supposed to be ok to call del_gendisk whileuserspace is frozen?
From: Pavel Machek
Date: Wed Mar 03 2010 - 16:51:18 EST
> > > 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
No, I don't think so. Have you considered all the various journalling
Definitely not in presence of I/O errors. Commit block can only be
written after previous blocks are successfully writen to the journal.
So lets see:
Write previous block, write commit block, write more blocks
<hibernation powerdown, restart>
Error writing previous block (block now contains garbage), leading to
journalling assumptions broken: commit block is there, but previous
blocks are not intact. Data loss.
...and that was the first I could think about. Lets not do
this. Barriers were invented for a reason.
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/