411 lines
12 KiB
C
411 lines
12 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* mm/percpu-vm.c - vmalloc area based chunk allocation
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*
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* Copyright (C) 2010 SUSE Linux Products GmbH
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* Copyright (C) 2010 Tejun Heo <tj@kernel.org>
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*
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* Chunks are mapped into vmalloc areas and populated page by page.
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* This is the default chunk allocator.
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*/
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#include "internal.h"
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static struct page *pcpu_chunk_page(struct pcpu_chunk *chunk,
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unsigned int cpu, int page_idx)
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{
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/* must not be used on pre-mapped chunk */
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WARN_ON(chunk->immutable);
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return vmalloc_to_page((void *)pcpu_chunk_addr(chunk, cpu, page_idx));
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}
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/**
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* pcpu_get_pages - get temp pages array
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*
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* Returns pointer to array of pointers to struct page which can be indexed
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* with pcpu_page_idx(). Note that there is only one array and accesses
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* should be serialized by pcpu_alloc_mutex.
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*
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* RETURNS:
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* Pointer to temp pages array on success.
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*/
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static struct page **pcpu_get_pages(void)
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{
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static struct page **pages;
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size_t pages_size = pcpu_nr_units * pcpu_unit_pages * sizeof(pages[0]);
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lockdep_assert_held(&pcpu_alloc_mutex);
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if (!pages)
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pages = pcpu_mem_zalloc(pages_size, GFP_KERNEL);
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return pages;
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}
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/**
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* pcpu_free_pages - free pages which were allocated for @chunk
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* @chunk: chunk pages were allocated for
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* @pages: array of pages to be freed, indexed by pcpu_page_idx()
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* @page_start: page index of the first page to be freed
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* @page_end: page index of the last page to be freed + 1
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*
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* Free pages [@page_start and @page_end) in @pages for all units.
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* The pages were allocated for @chunk.
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*/
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static void pcpu_free_pages(struct pcpu_chunk *chunk,
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struct page **pages, int page_start, int page_end)
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{
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unsigned int cpu;
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int i;
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for_each_possible_cpu(cpu) {
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for (i = page_start; i < page_end; i++) {
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struct page *page = pages[pcpu_page_idx(cpu, i)];
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if (page)
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__free_page(page);
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}
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}
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}
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/**
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* pcpu_alloc_pages - allocates pages for @chunk
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* @chunk: target chunk
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* @pages: array to put the allocated pages into, indexed by pcpu_page_idx()
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* @page_start: page index of the first page to be allocated
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* @page_end: page index of the last page to be allocated + 1
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* @gfp: allocation flags passed to the underlying allocator
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*
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* Allocate pages [@page_start,@page_end) into @pages for all units.
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* The allocation is for @chunk. Percpu core doesn't care about the
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* content of @pages and will pass it verbatim to pcpu_map_pages().
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*/
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static int pcpu_alloc_pages(struct pcpu_chunk *chunk,
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struct page **pages, int page_start, int page_end,
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gfp_t gfp)
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{
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unsigned int cpu, tcpu;
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int i;
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gfp |= __GFP_HIGHMEM;
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for_each_possible_cpu(cpu) {
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for (i = page_start; i < page_end; i++) {
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struct page **pagep = &pages[pcpu_page_idx(cpu, i)];
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*pagep = alloc_pages_node(cpu_to_node(cpu), gfp, 0);
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if (!*pagep)
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goto err;
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}
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}
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return 0;
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err:
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while (--i >= page_start)
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__free_page(pages[pcpu_page_idx(cpu, i)]);
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for_each_possible_cpu(tcpu) {
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if (tcpu == cpu)
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break;
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for (i = page_start; i < page_end; i++)
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__free_page(pages[pcpu_page_idx(tcpu, i)]);
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}
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return -ENOMEM;
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}
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/**
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* pcpu_pre_unmap_flush - flush cache prior to unmapping
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* @chunk: chunk the regions to be flushed belongs to
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* @page_start: page index of the first page to be flushed
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* @page_end: page index of the last page to be flushed + 1
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*
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* Pages in [@page_start,@page_end) of @chunk are about to be
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* unmapped. Flush cache. As each flushing trial can be very
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* expensive, issue flush on the whole region at once rather than
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* doing it for each cpu. This could be an overkill but is more
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* scalable.
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*/
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static void pcpu_pre_unmap_flush(struct pcpu_chunk *chunk,
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int page_start, int page_end)
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{
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flush_cache_vunmap(
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pcpu_chunk_addr(chunk, pcpu_low_unit_cpu, page_start),
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pcpu_chunk_addr(chunk, pcpu_high_unit_cpu, page_end));
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}
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static void __pcpu_unmap_pages(unsigned long addr, int nr_pages)
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{
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vunmap_range_noflush(addr, addr + (nr_pages << PAGE_SHIFT));
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}
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/**
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* pcpu_unmap_pages - unmap pages out of a pcpu_chunk
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* @chunk: chunk of interest
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* @pages: pages array which can be used to pass information to free
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* @page_start: page index of the first page to unmap
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* @page_end: page index of the last page to unmap + 1
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*
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* For each cpu, unmap pages [@page_start,@page_end) out of @chunk.
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* Corresponding elements in @pages were cleared by the caller and can
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* be used to carry information to pcpu_free_pages() which will be
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* called after all unmaps are finished. The caller should call
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* proper pre/post flush functions.
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*/
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static void pcpu_unmap_pages(struct pcpu_chunk *chunk,
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struct page **pages, int page_start, int page_end)
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{
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unsigned int cpu;
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int i;
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for_each_possible_cpu(cpu) {
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for (i = page_start; i < page_end; i++) {
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struct page *page;
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page = pcpu_chunk_page(chunk, cpu, i);
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WARN_ON(!page);
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pages[pcpu_page_idx(cpu, i)] = page;
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}
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__pcpu_unmap_pages(pcpu_chunk_addr(chunk, cpu, page_start),
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page_end - page_start);
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}
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}
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/**
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* pcpu_post_unmap_tlb_flush - flush TLB after unmapping
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* @chunk: pcpu_chunk the regions to be flushed belong to
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* @page_start: page index of the first page to be flushed
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* @page_end: page index of the last page to be flushed + 1
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*
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* Pages [@page_start,@page_end) of @chunk have been unmapped. Flush
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* TLB for the regions. This can be skipped if the area is to be
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* returned to vmalloc as vmalloc will handle TLB flushing lazily.
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*
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* As with pcpu_pre_unmap_flush(), TLB flushing also is done at once
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* for the whole region.
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*/
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static void pcpu_post_unmap_tlb_flush(struct pcpu_chunk *chunk,
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int page_start, int page_end)
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{
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flush_tlb_kernel_range(
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pcpu_chunk_addr(chunk, pcpu_low_unit_cpu, page_start),
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pcpu_chunk_addr(chunk, pcpu_high_unit_cpu, page_end));
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}
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static int __pcpu_map_pages(unsigned long addr, struct page **pages,
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int nr_pages)
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{
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return vmap_pages_range_noflush(addr, addr + (nr_pages << PAGE_SHIFT),
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PAGE_KERNEL, pages, PAGE_SHIFT);
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}
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/**
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* pcpu_map_pages - map pages into a pcpu_chunk
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* @chunk: chunk of interest
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* @pages: pages array containing pages to be mapped
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* @page_start: page index of the first page to map
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* @page_end: page index of the last page to map + 1
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*
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* For each cpu, map pages [@page_start,@page_end) into @chunk. The
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* caller is responsible for calling pcpu_post_map_flush() after all
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* mappings are complete.
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*
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* This function is responsible for setting up whatever is necessary for
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* reverse lookup (addr -> chunk).
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*/
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static int pcpu_map_pages(struct pcpu_chunk *chunk,
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struct page **pages, int page_start, int page_end)
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{
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unsigned int cpu, tcpu;
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int i, err;
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for_each_possible_cpu(cpu) {
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err = __pcpu_map_pages(pcpu_chunk_addr(chunk, cpu, page_start),
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&pages[pcpu_page_idx(cpu, page_start)],
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page_end - page_start);
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if (err < 0)
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goto err;
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for (i = page_start; i < page_end; i++)
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pcpu_set_page_chunk(pages[pcpu_page_idx(cpu, i)],
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chunk);
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}
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return 0;
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err:
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for_each_possible_cpu(tcpu) {
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if (tcpu == cpu)
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break;
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__pcpu_unmap_pages(pcpu_chunk_addr(chunk, tcpu, page_start),
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page_end - page_start);
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}
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pcpu_post_unmap_tlb_flush(chunk, page_start, page_end);
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return err;
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}
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/**
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* pcpu_post_map_flush - flush cache after mapping
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* @chunk: pcpu_chunk the regions to be flushed belong to
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* @page_start: page index of the first page to be flushed
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* @page_end: page index of the last page to be flushed + 1
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*
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* Pages [@page_start,@page_end) of @chunk have been mapped. Flush
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* cache.
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*
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* As with pcpu_pre_unmap_flush(), TLB flushing also is done at once
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* for the whole region.
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*/
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static void pcpu_post_map_flush(struct pcpu_chunk *chunk,
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int page_start, int page_end)
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{
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flush_cache_vmap(
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pcpu_chunk_addr(chunk, pcpu_low_unit_cpu, page_start),
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pcpu_chunk_addr(chunk, pcpu_high_unit_cpu, page_end));
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}
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/**
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* pcpu_populate_chunk - populate and map an area of a pcpu_chunk
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* @chunk: chunk of interest
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* @page_start: the start page
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* @page_end: the end page
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* @gfp: allocation flags passed to the underlying memory allocator
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*
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* For each cpu, populate and map pages [@page_start,@page_end) into
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* @chunk.
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*
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* CONTEXT:
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* pcpu_alloc_mutex, does GFP_KERNEL allocation.
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*/
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static int pcpu_populate_chunk(struct pcpu_chunk *chunk,
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int page_start, int page_end, gfp_t gfp)
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{
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struct page **pages;
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pages = pcpu_get_pages();
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if (!pages)
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return -ENOMEM;
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if (pcpu_alloc_pages(chunk, pages, page_start, page_end, gfp))
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return -ENOMEM;
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if (pcpu_map_pages(chunk, pages, page_start, page_end)) {
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pcpu_free_pages(chunk, pages, page_start, page_end);
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return -ENOMEM;
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}
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pcpu_post_map_flush(chunk, page_start, page_end);
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return 0;
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}
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/**
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* pcpu_depopulate_chunk - depopulate and unmap an area of a pcpu_chunk
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* @chunk: chunk to depopulate
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* @page_start: the start page
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* @page_end: the end page
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*
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* For each cpu, depopulate and unmap pages [@page_start,@page_end)
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* from @chunk.
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*
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* Caller is required to call pcpu_post_unmap_tlb_flush() if not returning the
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* region back to vmalloc() which will lazily flush the tlb.
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*
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* CONTEXT:
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* pcpu_alloc_mutex.
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*/
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static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk,
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int page_start, int page_end)
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{
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struct page **pages;
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/*
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* If control reaches here, there must have been at least one
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* successful population attempt so the temp pages array must
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* be available now.
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*/
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pages = pcpu_get_pages();
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BUG_ON(!pages);
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/* unmap and free */
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pcpu_pre_unmap_flush(chunk, page_start, page_end);
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pcpu_unmap_pages(chunk, pages, page_start, page_end);
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pcpu_free_pages(chunk, pages, page_start, page_end);
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}
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static struct pcpu_chunk *pcpu_create_chunk(gfp_t gfp)
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{
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struct pcpu_chunk *chunk;
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struct vm_struct **vms;
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chunk = pcpu_alloc_chunk(gfp);
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if (!chunk)
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return NULL;
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vms = pcpu_get_vm_areas(pcpu_group_offsets, pcpu_group_sizes,
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pcpu_nr_groups, pcpu_atom_size);
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if (!vms) {
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pcpu_free_chunk(chunk);
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return NULL;
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}
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chunk->data = vms;
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chunk->base_addr = vms[0]->addr - pcpu_group_offsets[0];
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pcpu_stats_chunk_alloc();
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trace_percpu_create_chunk(chunk->base_addr);
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return chunk;
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}
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static void pcpu_destroy_chunk(struct pcpu_chunk *chunk)
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{
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if (!chunk)
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return;
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pcpu_stats_chunk_dealloc();
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trace_percpu_destroy_chunk(chunk->base_addr);
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if (chunk->data)
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pcpu_free_vm_areas(chunk->data, pcpu_nr_groups);
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pcpu_free_chunk(chunk);
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}
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static struct page *pcpu_addr_to_page(void *addr)
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{
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return vmalloc_to_page(addr);
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}
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static int __init pcpu_verify_alloc_info(const struct pcpu_alloc_info *ai)
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{
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/* no extra restriction */
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return 0;
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}
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/**
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* pcpu_should_reclaim_chunk - determine if a chunk should go into reclaim
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* @chunk: chunk of interest
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*
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* This is the entry point for percpu reclaim. If a chunk qualifies, it is then
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* isolated and managed in separate lists at the back of pcpu_slot: sidelined
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* and to_depopulate respectively. The to_depopulate list holds chunks slated
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* for depopulation. They no longer contribute to pcpu_nr_empty_pop_pages once
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* they are on this list. Once depopulated, they are moved onto the sidelined
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* list which enables them to be pulled back in for allocation if no other chunk
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* can suffice the allocation.
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*/
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static bool pcpu_should_reclaim_chunk(struct pcpu_chunk *chunk)
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{
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/* do not reclaim either the first chunk or reserved chunk */
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if (chunk == pcpu_first_chunk || chunk == pcpu_reserved_chunk)
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return false;
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/*
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* If it is isolated, it may be on the sidelined list so move it back to
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* the to_depopulate list. If we hit at least 1/4 pages empty pages AND
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* there is no system-wide shortage of empty pages aside from this
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* chunk, move it to the to_depopulate list.
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*/
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return ((chunk->isolated && chunk->nr_empty_pop_pages) ||
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(pcpu_nr_empty_pop_pages >
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(PCPU_EMPTY_POP_PAGES_HIGH + chunk->nr_empty_pop_pages) &&
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chunk->nr_empty_pop_pages >= chunk->nr_pages / 4));
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}
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