Messages in this thread Patch in this message | | | From | Claudio Imbrenda <> | Subject | [PATCH v3 1/2] mm/vmalloc: add vmalloc_no_huge | Date | Thu, 10 Jun 2021 17:42:19 +0200 |
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The recent patches to add support for hugepage vmalloc mappings added a flag for __vmalloc_node_range to allow to request small 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 small 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 function is exported, therefore it is usable by modules.
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Uladzislau Rezki (Sony) <urezki@gmail.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Christoph Hellwig <hch@infradead.org> --- include/linux/vmalloc.h | 1 + mm/vmalloc.c | 16 ++++++++++++++++ 2 files changed, 17 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..296a2fcc3fbe 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -2998,6 +2998,22 @@ 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 -- 2.31.1
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