On Tue, Sep 22, 2020 at 04:06:03PM +0100, Matthew Wilcox wrote: > I don't think it makes sense to list all vmalloc-style allocators here. > It won't be updated by people who add new variations. How about this? > > * Free the virtually continuous memory area starting at @addr, as > * obtained from one of the vmalloc() family of APIs. This will > * usually also free the physical memory underlying the virtual > * allocation, but that memory is reference counted, so it will not > * be freed until the last user goes away. > * > * If @addr is NULL, no operation is performed. > > I'm trying to strike a balance between being accurate and not requiring > device driver authors to learn all about struct page. I may be too > close to the implementation to write good documentation for it. I think the above is sensible, but not enough. vmap really needs to be treated special, as by default area->pages for vmap is NULL. So for vfree to be useful on a vmap mapping, the callers needs to manually set it up by poking into the internals. Actually, I think we really want another API rather than vmap for that. Let me respin my series to include that.
