Re: oops with dual xeon 2.8ghz 4gb ram +smp, software raid, lvm,and xfs

[Andrew Morton]

Neil Brown <neilb@xxxxxxxxxxxxxxx> wrote:
>
> If a ->make_request_fn did synchronous IO things would definitely get
>  unstuck.   But I don't think they should and doubt if they do (md
>  certainly doesn't).

generic_make_request() can block in get_request_wait(), but I can't
immediately think of a way in which that can deadlock things, especially if
each level is using a distinct queue.

It could certainly deadlock if a higher-level make_request() caller
required allocation of two or more requests at a lower level - all we'd
need is N/2 proceses each trying to allocate two requests.  But such a
lockup could happen in the current code anyway..  
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