Re: [PATCH V3 (RESEND) 2/3] mm/sparsemem: Enable vmem_altmap support in vmemmap_alloc_block_buf()
From: Catalin Marinas <catalin.marinas@arm.com>
Date: 2020-07-02 14:07:59
Also in:
linux-arm-kernel, linux-mm, lkml
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) */
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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