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    SubjectRe: 2.6.27-rc4: lots of 'in_atomic():1, irqs_disabled():0' with software-raid1
    On Fri, 29 Aug 2008 17:36:08 +1000 Neil Brown <neilb@suse.de> wrote:

    > On Thursday August 28, akpm@linux-foundation.org wrote:
    > >
    > > I'm curious about how this happened.
    > >
    > > afaict from reading the code, this:
    > >
    > > rcu_read_lock();
    > > might_sleep();
    > > rcu_read_unlock();
    > >
    > > will warn if CONFIG_PREEMPT_RCU=n but won't warn if
    > > CONFIG_PREEMPT_RCU=y. If correct, that's a nasty trap.
    > >
    > > Is that what you did?
    >
    > Uhm..
    > $ grep PREEMPT /home/src/md-x86-64/.config
    > CONFIG_PREEMPT_NONE=y
    > # CONFIG_PREEMPT_VOLUNTARY is not set
    > # CONFIG_PREEMPT is not set
    > $ grep DEBUG_SPIN /home/src/md-x86-64/.config
    > CONFIG_DEBUG_SPINLOCK=y
    > CONFIG_DEBUG_SPINLOCK_SLEEP=y
    > $ grep RCU /home/src/md-x86-64/.config
    > CONFIG_CLASSIC_RCU=y
    > # CONFIG_RCU_TORTURE_TEST is not set
    >
    > This definitely doesn't report an error if I put "might_sleep" inside
    > rcu_read_lock. I tried to figure out why but got lost.

    CONFIG_DEBUG_SPINLOCK_SLEEP doesn't do much useful without
    CONFIG_PREEMPT=y. Perhaps we could improve the Kconfig situation
    there.

    The most fine Documentation/SubmitChecklist instructeth:

    12: Has been tested with CONFIG_PREEMPT, CONFIG_DEBUG_PREEMPT,
    CONFIG_DEBUG_SLAB, CONFIG_DEBUG_PAGEALLOC, CONFIG_DEBUG_MUTEXES,
    CONFIG_DEBUG_SPINLOCK, CONFIG_DEBUG_SPINLOCK_SLEEP all simultaneously
    enabled.

    (which might need updating for new goodies - it was written a while ago).



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