Sounds like I have arrived at a kernelnewbies question.
On Thu, 23 Oct 2003, Tim Hockin wrote:
> On Thu, Oct 23, 2003 at 01:00:57PM -0400, Mike Waychison wrote:
> > >Would a GFP_ATOMIC make a difference to the analysis?
>
> > Yes, sleeping within a spinlock is bad practice because it may
> > eventually deadlock. Pretend that the lock is taken, the call to
> > kmalloc is made, the mm system doesn't have any immidiately free memory
> > and through some flow of execution requires that a some pseudo-block
> > device backed filesystem needs to be mounted -> deadlock. I have no
> > idea if this is currently a likely scenario, however not sleeping within
> > a lock is 'The Right Thing' and should be avoided at all costs.
>
> it's worse than that. It's forbidden. It's a VERY likely deadlock scenario
> in the general sense, even if this particular case is not. If you need to
> lock something and you need to sleep holding that lock, use a semaphore.
>
>
I see.
But, I believe that the BKL is essentially a spinlock and it's used in all
sorts of places, including by me in the patch for autofs4.
Do I need to review this?
What's different about the BKL?
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