[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    [W:0.019 / U:53.856 seconds]
    ©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site