From 15a64f5a8870b5610b616a4aa753262dfaa5d76e Mon Sep 17 00:00:00 2001 From: Claudio Imbrenda Date: Thu, 24 Jun 2021 18:39:36 -0700 Subject: [PATCH] mm/vmalloc: add vmalloc_no_huge Patch series "mm: add vmalloc_no_huge and use it", v4. Add vmalloc_no_huge() and export it, so modules can allocate memory with small pages. Use the newly added vmalloc_no_huge() in KVM on s390 to get around a hardware limitation. This patch (of 2): Commit 121e6f3258fe3 ("mm/vmalloc: hugepage vmalloc mappings") added support for hugepage vmalloc mappings, it also added the flag VM_NO_HUGE_VMAP for __vmalloc_node_range to request the allocation to be performed with 0-order non-huge pages. This flag is not accessible when calling vmalloc, the only option is to call directly __vmalloc_node_range, which is not exported. This means that a module can't vmalloc memory with small pages. Case in point: KVM on s390x needs to vmalloc a large area, and it needs to be mapped with non-huge pages, because of a hardware limitation. This patch adds the function vmalloc_no_huge, which works like vmalloc, but it is guaranteed to always back the mapping using small pages. This new function is exported, therefore it is usable by modules. [akpm@linux-foundation.org: whitespace fixes, per Christoph] Link: https://lkml.kernel.org/r/20210614132357.10202-1-imbrenda@linux.ibm.com Link: https://lkml.kernel.org/r/20210614132357.10202-2-imbrenda@linux.ibm.com Fixes: 121e6f3258fe3 ("mm/vmalloc: hugepage vmalloc mappings") Signed-off-by: Claudio Imbrenda Reviewed-by: Uladzislau Rezki (Sony) Acked-by: Nicholas Piggin Reviewed-by: David Hildenbrand Acked-by: David Rientjes Cc: Uladzislau Rezki (Sony) Cc: Catalin Marinas Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Christoph Hellwig Cc: Cornelia Huck Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/vmalloc.h | 1 + mm/vmalloc.c | 17 +++++++++++++++++ 2 files changed, 18 insertions(+) diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h index 4d668abb6391..bfaaf0b6fa76 100644 --- a/include/linux/vmalloc.h +++ b/include/linux/vmalloc.h @@ -135,6 +135,7 @@ extern void *__vmalloc_node_range(unsigned long size, unsigned long align, const void *caller); void *__vmalloc_node(unsigned long size, unsigned long align, gfp_t gfp_mask, int node, const void *caller); +void *vmalloc_no_huge(unsigned long size); extern void vfree(const void *addr); extern void vfree_atomic(const void *addr); diff --git a/mm/vmalloc.c b/mm/vmalloc.c index a13ac524f6ff..fada19e17814 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -2998,6 +2998,23 @@ void *vmalloc(unsigned long size) } EXPORT_SYMBOL(vmalloc); +/** + * vmalloc_no_huge - allocate virtually contiguous memory using small pages + * @size: allocation size + * + * Allocate enough non-huge pages to cover @size from the page level + * allocator and map them into contiguous kernel virtual space. + * + * Return: pointer to the allocated memory or %NULL on error + */ +void *vmalloc_no_huge(unsigned long size) +{ + return __vmalloc_node_range(size, 1, VMALLOC_START, VMALLOC_END, + GFP_KERNEL, PAGE_KERNEL, VM_NO_HUGE_VMAP, + NUMA_NO_NODE, __builtin_return_address(0)); +} +EXPORT_SYMBOL(vmalloc_no_huge); + /** * vzalloc - allocate virtually contiguous memory with zero fill * @size: allocation size