On Thu, Jun 18, 2020 at 06:45:29AM +0530, Anshuman Khandual wrote:
> There are many instances where vmemap allocation is often switched between
> regular memory and device memory just based on whether altmap is available
> or not. vmemmap_alloc_block_buf() is used in various platforms to allocate
> vmemmap mappings. Lets also enable it to handle altmap based device memory
> allocation along with existing regular memory allocations. This will help
> in avoiding the altmap based allocation switch in many places.
>
> While here also implement a regular memory allocation fallback mechanism
> when the first preferred device memory allocation fails. This will ensure
> preserving the existing semantics on powerpc platform. To summarize there
> are three different methods to call vmemmap_alloc_block_buf().
>
> (., NULL, false) /* Allocate from system RAM */
> (., altmap, false) /* Allocate from altmap without any fallback */
> (., altmap, true) /* Allocate from altmap with fallback (system RAM) */
[...]
> diff --git a/arch/powerpc/mm/init_64.c b/arch/powerpc/mm/init_64.c
> index bc73abf0bc25..01e25b56eccb 100644
> --- a/arch/powerpc/mm/init_64.c
> +++ b/arch/powerpc/mm/init_64.c
> @@ -225,12 +225,12 @@ int __meminit vmemmap_populate(unsigned long start,
> unsigned long end, int node,
> * fall back to system memory if the altmap allocation fail.
> */
> if (altmap && !altmap_cross_boundary(altmap, start, page_size))
> {
> - p = altmap_alloc_block_buf(page_size, altmap);
> - if (!p)
> - pr_debug("altmap block allocation failed,
> falling back to system memory");
> + p = vmemmap_alloc_block_buf(page_size, node,
> + altmap, true);
> + } else {
> + p = vmemmap_alloc_block_buf(page_size, node,
> + NULL, false);
> }
> - if (!p)
> - p = vmemmap_alloc_block_buf(page_size, node);
> if (!p)
> return -ENOMEM;
Is the fallback argument actually necessary. It may be cleaner to just
leave the code as is with the choice between altmap and NULL. If an arch
needs a fallback (only powerpc), they have the fallback in place
already. I don't see the powerpc code any better after this change.
I'm fine with the altmap argument though.
--
Catalin
