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    SubjectRe: [RFC PATCH] freezer: revert 27920651fe "PM / Freezer: Make fake_signal_wake_up() wake TASK_KILLABLE tasks too"
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    On Mon, Oct 31, 2011 at 6:24 PM, Rafael J. Wysocki <rjw@sisk.pl> wrote:
    > On Monday, October 31, 2011, Tejun Heo wrote:
    >> Commit 27920651fe "PM / Freezer: Make fake_signal_wake_up() wake
    >> TASK_KILLABLE tasks too" made freezer wake up tasks in TASK_KILLABLE
    >> sleep too citing non-interruptible but killable sleeps in cifs and
    >> nfs.
    >>
    >> I don't think we can do this.  We should not send spurious unsolicited
    >> non-interruptible wakeups.  Most synchornization constructs are built
    >> to cope with spurious wakeups and any INTERRUPTIBLE sleep must be able
    >> to handle spurious wakeups but that's not true for KILLABLE sleeps -
    >> KILLABLE condition cannot be cancelled.
    >>
    >> This is probably okay for most cases but circumventing fundamental
    >> wakeup condition like this is asking for trouble.  Furthermore, I'm
    >> not sure the behavior change brought on by this change - breaking
    >> nfs/cifs uninterruptible operation guarantee - is correct.  If such
    >> behavior is desirable, the right thing to do is using intr mount
    >> option, not circumventing it from PM layer.
    >
    > Do you have any specific examples of breakage, or is it just that you _think_
    > it's not quite right?
    >
    > One patch depending on that change has been merged already and I have two
    > more in the queue, so I'd like to clarify this ASAP.  Jeff, Steve?
    >
    >> Signed-off-by: Tejun Heo <tj@kernel.org>
    >> Cc: Jeff Layton <jlayton@redhat.com>
    >> ---
    >> Neil, Steve, do the network filesystems need a way to indicate "I can
    >> either be killed or enter freezer"?

    Probably, yes, but I will defer to Jeff as he has looked
    more recently at these issues.

    I can explain cifs state, and disconnect/reconnection of sessions
    (and smb2 is a little more feature rich in this regard), but will
    let Jeff explain the more subtle points you are getting at.

    --
    Thanks,

    Steve
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