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    SubjectRe: XFS related Oops (suspend/resume related)
    On Tue, Nov 27, 2007 at 04:51:38PM +0100, Rafael J. Wysocki wrote:
    > On Monday, 26 of November 2007, Rafael J. Wysocki wrote:
    > > On Monday, 26 of November 2007, David Chinner wrote:
    > > > Now there's a message that I haven't seen in about 3 years.
    > > >
    > > > It indicates that the linux inode connected to the xfs_inode is not
    > > > the correct one. i.e. that the linux inode cache is out of step with
    > > > the XFS inode cache.
    > > >
    > > > Basically, that is not supposed to happen. I suspect that the way
    > > > threads are frozen is resulting in an inode lookup racing with
    > > > a reclaim. The reclaim thread gets stopped after any use threads,
    > > > and so we could have the situation that a process blocked in lookup
    > > > has the XFS inode reclaimed and reused before it gets unblocked.
    > > >
    > > > The question is why is it happening now when none of that code in
    > > > XFS has changed?
    > > >
    > > > Rafael, when are threads frozen? Only when they schedule or call
    > > > try_to_freeze()?
    > >
    > > Kernel threads freeze only when they call try_to_freeze(). User space tasks
    > > freeze while executing the signals handling code.
    > >
    > > > Did the freezer mechanism change in 2.6.23 (this is on 2.6.23.1)?
    > >
    > > Yes. Kernel threads are not sent fake signals by the freezer any more.
    >
    > Ah, sorry, this change has been merged after 2.6.23. However, before 2.6.23
    > we had another important change that caused all kernel threads to have
    > PF_NOFREEZE set by default, unless they call set_freezable() explicitly.

    So try_to_freeze() will never freeze a thread if it has not been
    set_freezable()? And xfsbufd will never be frozen?

    Cheers,

    Dave.
    --
    Dave Chinner
    Principal Engineer
    SGI Australian Software Group
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