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Diffstat (limited to '')
| -rw-r--r-- | mm/percpu-vm.c | 410 |
1 files changed, 410 insertions, 0 deletions
diff --git a/mm/percpu-vm.c b/mm/percpu-vm.c new file mode 100644 index 0000000000..2054c9213c --- /dev/null +++ b/mm/percpu-vm.c @@ -0,0 +1,410 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * mm/percpu-vm.c - vmalloc area based chunk allocation + * + * Copyright (C) 2010 SUSE Linux Products GmbH + * Copyright (C) 2010 Tejun Heo <tj@kernel.org> + * + * Chunks are mapped into vmalloc areas and populated page by page. + * This is the default chunk allocator. + */ +#include "internal.h" + +static struct page *pcpu_chunk_page(struct pcpu_chunk *chunk, + unsigned int cpu, int page_idx) +{ + /* must not be used on pre-mapped chunk */ + WARN_ON(chunk->immutable); + + return vmalloc_to_page((void *)pcpu_chunk_addr(chunk, cpu, page_idx)); +} + +/** + * pcpu_get_pages - get temp pages array + * + * Returns pointer to array of pointers to struct page which can be indexed + * with pcpu_page_idx(). Note that there is only one array and accesses + * should be serialized by pcpu_alloc_mutex. + * + * RETURNS: + * Pointer to temp pages array on success. + */ +static struct page **pcpu_get_pages(void) +{ + static struct page **pages; + size_t pages_size = pcpu_nr_units * pcpu_unit_pages * sizeof(pages[0]); + + lockdep_assert_held(&pcpu_alloc_mutex); + + if (!pages) + pages = pcpu_mem_zalloc(pages_size, GFP_KERNEL); + return pages; +} + +/** + * pcpu_free_pages - free pages which were allocated for @chunk + * @chunk: chunk pages were allocated for + * @pages: array of pages to be freed, indexed by pcpu_page_idx() + * @page_start: page index of the first page to be freed + * @page_end: page index of the last page to be freed + 1 + * + * Free pages [@page_start and @page_end) in @pages for all units. + * The pages were allocated for @chunk. + */ +static void pcpu_free_pages(struct pcpu_chunk *chunk, + struct page **pages, int page_start, int page_end) +{ + unsigned int cpu; + int i; + + for_each_possible_cpu(cpu) { + for (i = page_start; i < page_end; i++) { + struct page *page = pages[pcpu_page_idx(cpu, i)]; + + if (page) + __free_page(page); + } + } +} + +/** + * pcpu_alloc_pages - allocates pages for @chunk + * @chunk: target chunk + * @pages: array to put the allocated pages into, indexed by pcpu_page_idx() + * @page_start: page index of the first page to be allocated + * @page_end: page index of the last page to be allocated + 1 + * @gfp: allocation flags passed to the underlying allocator + * + * Allocate pages [@page_start,@page_end) into @pages for all units. + * The allocation is for @chunk. Percpu core doesn't care about the + * content of @pages and will pass it verbatim to pcpu_map_pages(). + */ +static int pcpu_alloc_pages(struct pcpu_chunk *chunk, + struct page **pages, int page_start, int page_end, + gfp_t gfp) +{ + unsigned int cpu, tcpu; + int i; + + gfp |= __GFP_HIGHMEM; + + for_each_possible_cpu(cpu) { + for (i = page_start; i < page_end; i++) { + struct page **pagep = &pages[pcpu_page_idx(cpu, i)]; + + *pagep = alloc_pages_node(cpu_to_node(cpu), gfp, 0); + if (!*pagep) + goto err; + } + } + return 0; + +err: + while (--i >= page_start) + __free_page(pages[pcpu_page_idx(cpu, i)]); + + for_each_possible_cpu(tcpu) { + if (tcpu == cpu) + break; + for (i = page_start; i < page_end; i++) + __free_page(pages[pcpu_page_idx(tcpu, i)]); + } + return -ENOMEM; +} + +/** + * pcpu_pre_unmap_flush - flush cache prior to unmapping + * @chunk: chunk the regions to be flushed belongs to + * @page_start: page index of the first page to be flushed + * @page_end: page index of the last page to be flushed + 1 + * + * Pages in [@page_start,@page_end) of @chunk are about to be + * unmapped. Flush cache. As each flushing trial can be very + * expensive, issue flush on the whole region at once rather than + * doing it for each cpu. This could be an overkill but is more + * scalable. + */ +static void pcpu_pre_unmap_flush(struct pcpu_chunk *chunk, + int page_start, int page_end) +{ + flush_cache_vunmap( + pcpu_chunk_addr(chunk, pcpu_low_unit_cpu, page_start), + pcpu_chunk_addr(chunk, pcpu_high_unit_cpu, page_end)); +} + +static void __pcpu_unmap_pages(unsigned long addr, int nr_pages) +{ + vunmap_range_noflush(addr, addr + (nr_pages << PAGE_SHIFT)); +} + +/** + * pcpu_unmap_pages - unmap pages out of a pcpu_chunk + * @chunk: chunk of interest + * @pages: pages array which can be used to pass information to free + * @page_start: page index of the first page to unmap + * @page_end: page index of the last page to unmap + 1 + * + * For each cpu, unmap pages [@page_start,@page_end) out of @chunk. + * Corresponding elements in @pages were cleared by the caller and can + * be used to carry information to pcpu_free_pages() which will be + * called after all unmaps are finished. The caller should call + * proper pre/post flush functions. + */ +static void pcpu_unmap_pages(struct pcpu_chunk *chunk, + struct page **pages, int page_start, int page_end) +{ + unsigned int cpu; + int i; + + for_each_possible_cpu(cpu) { + for (i = page_start; i < page_end; i++) { + struct page *page; + + page = pcpu_chunk_page(chunk, cpu, i); + WARN_ON(!page); + pages[pcpu_page_idx(cpu, i)] = page; + } + __pcpu_unmap_pages(pcpu_chunk_addr(chunk, cpu, page_start), + page_end - page_start); + } +} + +/** + * pcpu_post_unmap_tlb_flush - flush TLB after unmapping + * @chunk: pcpu_chunk the regions to be flushed belong to + * @page_start: page index of the first page to be flushed + * @page_end: page index of the last page to be flushed + 1 + * + * Pages [@page_start,@page_end) of @chunk have been unmapped. Flush + * TLB for the regions. This can be skipped if the area is to be + * returned to vmalloc as vmalloc will handle TLB flushing lazily. + * + * As with pcpu_pre_unmap_flush(), TLB flushing also is done at once + * for the whole region. + */ +static void pcpu_post_unmap_tlb_flush(struct pcpu_chunk *chunk, + int page_start, int page_end) +{ + flush_tlb_kernel_range( + pcpu_chunk_addr(chunk, pcpu_low_unit_cpu, page_start), + pcpu_chunk_addr(chunk, pcpu_high_unit_cpu, page_end)); +} + +static int __pcpu_map_pages(unsigned long addr, struct page **pages, + int nr_pages) +{ + return vmap_pages_range_noflush(addr, addr + (nr_pages << PAGE_SHIFT), + PAGE_KERNEL, pages, PAGE_SHIFT); +} + +/** + * pcpu_map_pages - map pages into a pcpu_chunk + * @chunk: chunk of interest + * @pages: pages array containing pages to be mapped + * @page_start: page index of the first page to map + * @page_end: page index of the last page to map + 1 + * + * For each cpu, map pages [@page_start,@page_end) into @chunk. The + * caller is responsible for calling pcpu_post_map_flush() after all + * mappings are complete. + * + * This function is responsible for setting up whatever is necessary for + * reverse lookup (addr -> chunk). + */ +static int pcpu_map_pages(struct pcpu_chunk *chunk, + struct page **pages, int page_start, int page_end) +{ + unsigned int cpu, tcpu; + int i, err; + + for_each_possible_cpu(cpu) { + err = __pcpu_map_pages(pcpu_chunk_addr(chunk, cpu, page_start), + &pages[pcpu_page_idx(cpu, page_start)], + page_end - page_start); + if (err < 0) + goto err; + + for (i = page_start; i < page_end; i++) + pcpu_set_page_chunk(pages[pcpu_page_idx(cpu, i)], + chunk); + } + return 0; +err: + for_each_possible_cpu(tcpu) { + if (tcpu == cpu) + break; + __pcpu_unmap_pages(pcpu_chunk_addr(chunk, tcpu, page_start), + page_end - page_start); + } + pcpu_post_unmap_tlb_flush(chunk, page_start, page_end); + return err; +} + +/** + * pcpu_post_map_flush - flush cache after mapping + * @chunk: pcpu_chunk the regions to be flushed belong to + * @page_start: page index of the first page to be flushed + * @page_end: page index of the last page to be flushed + 1 + * + * Pages [@page_start,@page_end) of @chunk have been mapped. Flush + * cache. + * + * As with pcpu_pre_unmap_flush(), TLB flushing also is done at once + * for the whole region. + */ +static void pcpu_post_map_flush(struct pcpu_chunk *chunk, + int page_start, int page_end) +{ + flush_cache_vmap( + pcpu_chunk_addr(chunk, pcpu_low_unit_cpu, page_start), + pcpu_chunk_addr(chunk, pcpu_high_unit_cpu, page_end)); +} + +/** + * pcpu_populate_chunk - populate and map an area of a pcpu_chunk + * @chunk: chunk of interest + * @page_start: the start page + * @page_end: the end page + * @gfp: allocation flags passed to the underlying memory allocator + * + * For each cpu, populate and map pages [@page_start,@page_end) into + * @chunk. + * + * CONTEXT: + * pcpu_alloc_mutex, does GFP_KERNEL allocation. + */ +static int pcpu_populate_chunk(struct pcpu_chunk *chunk, + int page_start, int page_end, gfp_t gfp) +{ + struct page **pages; + + pages = pcpu_get_pages(); + if (!pages) + return -ENOMEM; + + if (pcpu_alloc_pages(chunk, pages, page_start, page_end, gfp)) + return -ENOMEM; + + if (pcpu_map_pages(chunk, pages, page_start, page_end)) { + pcpu_free_pages(chunk, pages, page_start, page_end); + return -ENOMEM; + } + pcpu_post_map_flush(chunk, page_start, page_end); + + return 0; +} + +/** + * pcpu_depopulate_chunk - depopulate and unmap an area of a pcpu_chunk + * @chunk: chunk to depopulate + * @page_start: the start page + * @page_end: the end page + * + * For each cpu, depopulate and unmap pages [@page_start,@page_end) + * from @chunk. + * + * Caller is required to call pcpu_post_unmap_tlb_flush() if not returning the + * region back to vmalloc() which will lazily flush the tlb. + * + * CONTEXT: + * pcpu_alloc_mutex. + */ +static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk, + int page_start, int page_end) +{ + struct page **pages; + + /* + * If control reaches here, there must have been at least one + * successful population attempt so the temp pages array must + * be available now. + */ + pages = pcpu_get_pages(); + BUG_ON(!pages); + + /* unmap and free */ + pcpu_pre_unmap_flush(chunk, page_start, page_end); + + pcpu_unmap_pages(chunk, pages, page_start, page_end); + + pcpu_free_pages(chunk, pages, page_start, page_end); +} + +static struct pcpu_chunk *pcpu_create_chunk(gfp_t gfp) +{ + struct pcpu_chunk *chunk; + struct vm_struct **vms; + + chunk = pcpu_alloc_chunk(gfp); + if (!chunk) + return NULL; + + vms = pcpu_get_vm_areas(pcpu_group_offsets, pcpu_group_sizes, + pcpu_nr_groups, pcpu_atom_size); + if (!vms) { + pcpu_free_chunk(chunk); + return NULL; + } + + chunk->data = vms; + chunk->base_addr = vms[0]->addr - pcpu_group_offsets[0]; + + pcpu_stats_chunk_alloc(); + trace_percpu_create_chunk(chunk->base_addr); + + return chunk; +} + +static void pcpu_destroy_chunk(struct pcpu_chunk *chunk) +{ + if (!chunk) + return; + + pcpu_stats_chunk_dealloc(); + trace_percpu_destroy_chunk(chunk->base_addr); + + if (chunk->data) + pcpu_free_vm_areas(chunk->data, pcpu_nr_groups); + pcpu_free_chunk(chunk); +} + +static struct page *pcpu_addr_to_page(void *addr) +{ + return vmalloc_to_page(addr); +} + +static int __init pcpu_verify_alloc_info(const struct pcpu_alloc_info *ai) +{ + /* no extra restriction */ + return 0; +} + +/** + * pcpu_should_reclaim_chunk - determine if a chunk should go into reclaim + * @chunk: chunk of interest + * + * This is the entry point for percpu reclaim. If a chunk qualifies, it is then + * isolated and managed in separate lists at the back of pcpu_slot: sidelined + * and to_depopulate respectively. The to_depopulate list holds chunks slated + * for depopulation. They no longer contribute to pcpu_nr_empty_pop_pages once + * they are on this list. Once depopulated, they are moved onto the sidelined + * list which enables them to be pulled back in for allocation if no other chunk + * can suffice the allocation. + */ +static bool pcpu_should_reclaim_chunk(struct pcpu_chunk *chunk) +{ + /* do not reclaim either the first chunk or reserved chunk */ + if (chunk == pcpu_first_chunk || chunk == pcpu_reserved_chunk) + return false; + + /* + * If it is isolated, it may be on the sidelined list so move it back to + * the to_depopulate list. If we hit at least 1/4 pages empty pages AND + * there is no system-wide shortage of empty pages aside from this + * chunk, move it to the to_depopulate list. + */ + return ((chunk->isolated && chunk->nr_empty_pop_pages) || + (pcpu_nr_empty_pop_pages > + (PCPU_EMPTY_POP_PAGES_HIGH + chunk->nr_empty_pop_pages) && + chunk->nr_empty_pop_pages >= chunk->nr_pages / 4)); +} |