Re: [dm-devel] Re: [PATCH resubmit] do_mount: reduce stack consumption

[Nick Piggin <nickpiggin@yahoo.com.au>]

Neil Brown wrote:
> On Tuesday November 8, nickpiggin@yahoo.com.au wrote:

> > Possibly it could go into struct io_context?
>
>
> My quick reading of the code says that we could have to 
> allocate the struct right there in generic_make_request, and I don't
> think we can be certain that such an allocation will succeed.
>
> Code that uses io_context can limp along if it doesn't exist.  
> The new generic_make_request needs this bio_list to be present 
> or it cannot do it's job.

You can ask for the io context without having a request. However,
there is nothing like a mempool for them so code really should be
able to limp along without them.

I guess it would be silly to require such an allocation to succeed
here, because the block layer is pretty free of OOM deadlocks.

--
SUSE Labs, Novell Inc.

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