[lkml]   [2007]   [Jul]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [RFC][PATCH -mm] Freezer: Handle uninterruptible tasks
On Mon, 9 Jul 2007, Jeremy Maitin-Shepard wrote:

> Pavel Machek <> writes:
> [snip]
> > I don't know how to do that mechanism... but if we knew where to trap
> > filesystem writes, we could simply freeze at that point, and at that
> > point only, no?
> Any operation at all that has an external effect must not occur after
> the snapshot is made; otherwise, there will be random hard-to-find
> corruptions and other problems occurring as a result. Thus, for
> example, any writes (either directly or indirectly through e.g. a
> filesystem) to non-volatile storage, any network traffic, any
> communication with hardware like a printer must be prevented after the
> snapshot.

You have forgotten one critical point: The writes to save the snapshot
image must be allowed. That's what makes it really hard.

Alan Stern

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2007-07-09 16:49    [from the cache]
©2003-2014 Jasper Spaans. hosted at Digital Ocean