On Sun, Aug 12, 2007 at 11:44:00PM -0700, Daniel Phillips ([EMAIL PROTECTED])
wrote:
> On Sunday 12 August 2007 22:36, I wrote:
> > Note! There are two more issues I forgot to mention earlier.
>
> Oops, and there is also:
>
> 3) The bio throttle, which is supposed to prevent deadlock, can itself
> deadlock. Let me see if I can remember how it goes.
>
> * generic_make_request puts a bio in flight
> * the bio gets past the throttle and initiates network IO
> * net calls sk_alloc->alloc_pages->shrink_caches
> * shrink_caches submits a bio recursively to our block device
> * this bio blocks on the throttle
> * net may never get the memory it needs, and we are wedged
If system is in such condition, it is already broken - throttle limit
must be lowered (next time) not to allow such situation.
--
Evgeniy Polyakov
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