Re: vmalloc: Return page array on vunmap

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

On Thursday 27 March 2008 15:18, Christoph Lameter wrote:
> Make vunmap return the page array that was used at vmap. This is useful
> if one has no structures to track the page array but simply stores the
> virtual address somewhere. The disposition of the page array can then
> be decided upon by the caller after vunmap has torn down the mapping.
>
> vfree() may now also be used instead of vunmap. vfree() will release the
> page array after vunmap'ping it. If vfree() is called to free the page
> array then the page array must either be
>
> 1. Allocated via the slab allocator
>
> 2. Allocated via vmalloc but then VM_VPAGES must have been passed at
>    vunmap to specify that a vfree is needed.

Is this really for something important? Because vmap/vunmap is so slow
and unscalable that it is pretty well unusable for any kind of dynamic
allocations. I have mostly rewritten it so it is a lot more scalable,
but all these little patches will make annoying rejects... Can it wait?

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