percpu-vm.c | Explore in Territory

// 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 <[email protected]>
 *
 * 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)
{ … }

/**
 * 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)
{ … }

/**
 * 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)
{ … }

/**
 * 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)
{ … }

/**
 * 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)
{ … }

static void __pcpu_unmap_pages(unsigned long addr, int nr_pages)
{ … }

/**
 * 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)
{ … }

/**
 * 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)
{ … }

static int __pcpu_map_pages(unsigned long addr, struct page **pages,
			    int nr_pages)
{ … }

/**
 * 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)
{ … }

/**
 * 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)
{ … }

/**
 * 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)
{ … }

/**
 * 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)
{ … }

static struct pcpu_chunk *pcpu_create_chunk(gfp_t gfp)
{ … }

static void pcpu_destroy_chunk(struct pcpu_chunk *chunk)
{ … }

static struct page *pcpu_addr_to_page(void *addr)
{ … }

static int __init pcpu_verify_alloc_info(const struct pcpu_alloc_info *ai)
{ … }

/**
 * 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)
{ … }
linux/mm/percpu-vm.c
