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    SubjectRe: [GIT PULL pm-next] freezer: fix various bugs and simplify implementation
    On Monday, August 22, 2011, Tejun Heo wrote:
    > Hello, Rafael.
    > On Sun, Aug 21, 2011 at 08:03:14PM +0200, Rafael J. Wysocki wrote:
    > > From: Rafael J. Wysocki <>
    > > Subject: PM / Freezer: Move might_sleep() from try_to_freeze()
    > >
    > > There are some code paths that call try_to_freeze() from interrupt
    > > context, but doing so they know that the current process cannot
    > > possible be freezing (e.g. during reboot on ARM). However, the
    > > recently added might_sleep() annotation in try_to_freeze()
    > > triggers in those cases, making it look like there were bugs in
    > > those places, which really isn't the case.
    > >
    > > Therefore move might_sleep() from try_to_freeze() to
    > > __refrigerator() so that it doesn't produce false positives.
    > Hmmm... I can't quite agree with this change. Some invocations of
    > try_to_freeze() can be very difficult to trigger. Freezing isn't a
    > frequent operation after some try_to_freeze() can be buried in weird
    > places. might_sleep() is exactly to detect context bugs in these
    > situations. If a code path is called from both sleepable and
    > unsleepable context and it knows that the latter wouldn't happen if
    > the system is freezing, that code path should conditionalize
    > invocation of try_to_freeze() based on its knowledge of context. That
    > way, all other normal cases get the might_sleep() protection and the
    > peculiar logic in that code path is explicitly described - win win.
    > Can you please point me to where the problem was?

    Apparently, during reboot on ARM try_to_freeze() is called via
    do_signal() with interrupts disabled.


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