diff options
Diffstat (limited to 'mm/percpu.c')
| -rw-r--r-- | mm/percpu.c | 1522 |
1 files changed, 954 insertions, 568 deletions
diff --git a/mm/percpu.c b/mm/percpu.c index bd4130a69bbc..59d44d61f5f1 100644 --- a/mm/percpu.c +++ b/mm/percpu.c @@ -4,44 +4,53 @@ * Copyright (C) 2009 SUSE Linux Products GmbH * Copyright (C) 2009 Tejun Heo <tj@kernel.org> * - * This file is released under the GPLv2. + * Copyright (C) 2017 Facebook Inc. + * Copyright (C) 2017 Dennis Zhou <dennisszhou@gmail.com> * - * This is percpu allocator which can handle both static and dynamic - * areas. Percpu areas are allocated in chunks. Each chunk is - * consisted of boot-time determined number of units and the first - * chunk is used for static percpu variables in the kernel image - * (special boot time alloc/init handling necessary as these areas - * need to be brought up before allocation services are running). - * Unit grows as necessary and all units grow or shrink in unison. - * When a chunk is filled up, another chunk is allocated. + * This file is released under the GPLv2 license. + * + * The percpu allocator handles both static and dynamic areas. Percpu + * areas are allocated in chunks which are divided into units. There is + * a 1-to-1 mapping for units to possible cpus. These units are grouped + * based on NUMA properties of the machine. * * c0 c1 c2 * ------------------- ------------------- ------------ * | u0 | u1 | u2 | u3 | | u0 | u1 | u2 | u3 | | u0 | u1 | u * ------------------- ...... ------------------- .... ------------ * - * Allocation is done in offset-size areas of single unit space. Ie, - * an area of 512 bytes at 6k in c1 occupies 512 bytes at 6k of c1:u0, - * c1:u1, c1:u2 and c1:u3. On UMA, units corresponds directly to - * cpus. On NUMA, the mapping can be non-linear and even sparse. - * Percpu access can be done by configuring percpu base registers - * according to cpu to unit mapping and pcpu_unit_size. - * - * There are usually many small percpu allocations many of them being - * as small as 4 bytes. The allocator organizes chunks into lists - * according to free size and tries to allocate from the fullest one. - * Each chunk keeps the maximum contiguous area size hint which is - * guaranteed to be equal to or larger than the maximum contiguous - * area in the chunk. This helps the allocator not to iterate the - * chunk maps unnecessarily. - * - * Allocation state in each chunk is kept using an array of integers - * on chunk->map. A positive value in the map represents a free - * region and negative allocated. Allocation inside a chunk is done - * by scanning this map sequentially and serving the first matching - * entry. This is mostly copied from the percpu_modalloc() allocator. - * Chunks can be determined from the address using the index field - * in the page struct. The index field contains a pointer to the chunk. + * Allocation is done by offsets into a unit's address space. Ie., an + * area of 512 bytes at 6k in c1 occupies 512 bytes at 6k in c1:u0, + * c1:u1, c1:u2, etc. On NUMA machines, the mapping may be non-linear + * and even sparse. Access is handled by configuring percpu base + * registers according to the cpu to unit mappings and offsetting the + * base address using pcpu_unit_size. + * + * There is special consideration for the first chunk which must handle + * the static percpu variables in the kernel image as allocation services + * are not online yet. In short, the first chunk is structured like so: + * + * <Static | [Reserved] | Dynamic> + * + * The static data is copied from the original section managed by the + * linker. The reserved section, if non-zero, primarily manages static + * percpu variables from kernel modules. Finally, the dynamic section + * takes care of normal allocations. + * + * The allocator organizes chunks into lists according to free size and + * tries to allocate from the fullest chunk first. Each chunk is managed + * by a bitmap with metadata blocks. The allocation map is updated on + * every allocation and free to reflect the current state while the boundary + * map is only updated on allocation. Each metadata block contains + * information to help mitigate the need to iterate over large portions + * of the bitmap. The reverse mapping from page to chunk is stored in + * the page's index. Lastly, units are lazily backed and grow in unison. + * + * There is a unique conversion that goes on here between bytes and bits. + * Each bit represents a fragment of size PCPU_MIN_ALLOC_SIZE. The chunk + * tracks the number of pages it is responsible for in nr_pages. Helper + * functions are used to convert from between the bytes, bits, and blocks. + * All hints are managed in bits unless explicitly stated. * * To use this allocator, arch code should do the following: * @@ -58,6 +67,7 @@ #include <linux/bitmap.h> #include <linux/bootmem.h> #include <linux/err.h> +#include <linux/lcm.h> #include <linux/list.h> #include <linux/log2.h> #include <linux/mm.h> @@ -81,10 +91,9 @@ #include "percpu-internal.h" -#define PCPU_SLOT_BASE_SHIFT 5 /* 1-31 shares the same slot */ -#define PCPU_DFL_MAP_ALLOC 16 /* start a map with 16 ents */ -#define PCPU_ATOMIC_MAP_MARGIN_LOW 32 -#define PCPU_ATOMIC_MAP_MARGIN_HIGH 64 +/* the slots are sorted by free bytes left, 1-31 bytes share the same slot */ +#define PCPU_SLOT_BASE_SHIFT 5 + #define PCPU_EMPTY_POP_PAGES_LOW 2 #define PCPU_EMPTY_POP_PAGES_HIGH 4 @@ -140,13 +149,10 @@ struct pcpu_chunk *pcpu_first_chunk __ro_after_init; /* * Optional reserved chunk. This chunk reserves part of the first - * chunk and serves it for reserved allocations. The amount of - * reserved offset is in pcpu_reserved_chunk_limit. When reserved - * area doesn't exist, the following variables contain NULL and 0 - * respectively. + * chunk and serves it for reserved allocations. When the reserved + * region doesn't exist, the following variable is NULL. */ struct pcpu_chunk *pcpu_reserved_chunk __ro_after_init; -static int pcpu_reserved_chunk_limit __ro_after_init; DEFINE_SPINLOCK(pcpu_lock); /* all internal data structures */ static DEFINE_MUTEX(pcpu_alloc_mutex); /* chunk create/destroy, [de]pop, map ext */ @@ -160,7 +166,7 @@ static LIST_HEAD(pcpu_map_extend_chunks); * The number of empty populated pages, protected by pcpu_lock. The * reserved chunk doesn't contribute to the count. */ -static int pcpu_nr_empty_pop_pages; +int pcpu_nr_empty_pop_pages; /* * Balance work is used to populate or destroy chunks asynchronously. We @@ -179,19 +185,26 @@ static void pcpu_schedule_balance_work(void) schedule_work(&pcpu_balance_work); } -static bool pcpu_addr_in_first_chunk(void *addr) +/** + * pcpu_addr_in_chunk - check if the address is served from this chunk + * @chunk: chunk of interest + * @addr: percpu address + * + * RETURNS: + * True if the address is served from this chunk. + */ +static bool pcpu_addr_in_chunk(struct pcpu_chunk *chunk, void *addr) { - void *first_start = pcpu_first_chunk->base_addr; + void *start_addr, *end_addr; - return addr >= first_start && addr < first_start + pcpu_unit_size; -} + if (!chunk) + return false; -static bool pcpu_addr_in_reserved_chunk(void *addr) -{ - void *first_start = pcpu_first_chunk->base_addr; + start_addr = chunk->base_addr + chunk->start_offset; + end_addr = chunk->base_addr + chunk->nr_pages * PAGE_SIZE - + chunk->end_offset; - return addr >= first_start && - addr < first_start + pcpu_reserved_chunk_limit; + return addr >= start_addr && addr < end_addr; } static int __pcpu_size_to_slot(int size) @@ -209,10 +222,10 @@ static int pcpu_size_to_slot(int size) static int pcpu_chunk_slot(const struct pcpu_chunk *chunk) { - if (chunk->free_size < sizeof(int) || chunk->contig_hint < sizeof(int)) + if (chunk->free_bytes < PCPU_MIN_ALLOC_SIZE || chunk->contig_bits == 0) return 0; - return pcpu_size_to_slot(chunk->free_size); + return pcpu_size_to_slot(chunk->free_bytes); } /* set the pointer to a chunk in a page struct */ @@ -232,42 +245,200 @@ static int __maybe_unused pcpu_page_idx(unsigned int cpu, int page_idx) return pcpu_unit_map[cpu] * pcpu_unit_pages + page_idx; } +static unsigned long pcpu_unit_page_offset(unsigned int cpu, int page_idx) +{ + return pcpu_unit_offsets[cpu] + (page_idx << PAGE_SHIFT); +} + static unsigned long pcpu_chunk_addr(struct pcpu_chunk *chunk, unsigned int cpu, int page_idx) { - return (unsigned long)chunk->base_addr + pcpu_unit_offsets[cpu] + - (page_idx << PAGE_SHIFT); + return (unsigned long)chunk->base_addr + + pcpu_unit_page_offset(cpu, page_idx); } -static void __maybe_unused pcpu_next_unpop(struct pcpu_chunk *chunk, - int *rs, int *re, int end) +static void pcpu_next_unpop(unsigned long *bitmap, int *rs, int *re, int end) { - *rs = find_next_zero_bit(chunk->populated, end, *rs); - *re = find_next_bit(chunk->populated, end, *rs + 1); + *rs = find_next_zero_bit(bitmap, end, *rs); + *re = find_next_bit(bitmap, end, *rs + 1); } -static void __maybe_unused pcpu_next_pop(struct pcpu_chunk *chunk, - int *rs, int *re, int end) +static void pcpu_next_pop(unsigned long *bitmap, int *rs, int *re, int end) { - *rs = find_next_bit(chunk->populated, end, *rs); - *re = find_next_zero_bit(chunk->populated, end, *rs + 1); + *rs = find_next_bit(bitmap, end, *rs); + *re = find_next_zero_bit(bitmap, end, *rs + 1); } /* - * (Un)populated page region iterators. Iterate over (un)populated - * page regions between @start and @end in @chunk. @rs and @re should - * be integer variables and will be set to start and end page index of - * the current region. + * Bitmap region iterators. Iterates over the bitmap between + * [@start, @end) in @chunk. @rs and @re should be integer variables + * and will be set to start and end index of the current free region. + */ +#define pcpu_for_each_unpop_region(bitmap, rs, re, start, end) \ + for ((rs) = (start), pcpu_next_unpop((bitmap), &(rs), &(re), (end)); \ + (rs) < (re); \ + (rs) = (re) + 1, pcpu_next_unpop((bitmap), &(rs), &(re), (end))) + +#define pcpu_for_each_pop_region(bitmap, rs, re, start, end) \ + for ((rs) = (start), pcpu_next_pop((bitmap), &(rs), &(re), (end)); \ + (rs) < (re); \ + (rs) = (re) + 1, pcpu_next_pop((bitmap), &(rs), &(re), (end))) + +/* + * The following are helper functions to help access bitmaps and convert + * between bitmap offsets to address offsets. + */ +static unsigned long *pcpu_index_alloc_map(struct pcpu_chunk *chunk, int index) +{ + return chunk->alloc_map + + (index * PCPU_BITMAP_BLOCK_BITS / BITS_PER_LONG); +} + +static unsigned long pcpu_off_to_block_index(int off) +{ + return off / PCPU_BITMAP_BLOCK_BITS; +} + +static unsigned long pcpu_off_to_block_off(int off) +{ + return off & (PCPU_BITMAP_BLOCK_BITS - 1); +} + +static unsigned long pcpu_block_off_to_off(int index, int off) +{ + return index * PCPU_BITMAP_BLOCK_BITS + off; +} + +/** + * pcpu_next_md_free_region - finds the next hint free area + * @chunk: chunk of interest + * @bit_off: chunk offset + * @bits: size of free area + * + * Helper function for pcpu_for_each_md_free_region. It checks + * block->contig_hint and performs aggregation across blocks to find the + * next hint. It modifies bit_off and bits in-place to be consumed in the + * loop. + */ +static void pcpu_next_md_free_region(struct pcpu_chunk *chunk, int *bit_off, + int *bits) +{ + int i = pcpu_off_to_block_index(*bit_off); + int block_off = pcpu_off_to_block_off(*bit_off); + struct pcpu_block_md *block; + + *bits = 0; + for (block = chunk->md_blocks + i; i < pcpu_chunk_nr_blocks(chunk); + block++, i++) { + /* handles contig area across blocks */ + if (*bits) { + *bits += block->left_free; + if (block->left_free == PCPU_BITMAP_BLOCK_BITS) + continue; + return; + } + + /* + * This checks three things. First is there a contig_hint to + * check. Second, have we checked this hint before by + * comparing the block_off. Third, is this the same as the + * right contig hint. In the last case, it spills over into + * the next block and should be handled by the contig area + * across blocks code. + */ + *bits = block->contig_hint; + if (*bits && block->contig_hint_start >= block_off && + *bits + block->contig_hint_start < PCPU_BITMAP_BLOCK_BITS) { + *bit_off = pcpu_block_off_to_off(i, + block->contig_hint_start); + return; + } + + *bits = block->right_free; + *bit_off = (i + 1) * PCPU_BITMAP_BLOCK_BITS - block->right_free; + } +} + +/** + * pcpu_next_fit_region - finds fit areas for a given allocation request + * @chunk: chunk of interest + * @alloc_bits: size of allocation + * @align: alignment of area (max PAGE_SIZE) + * @bit_off: chunk offset + * @bits: size of free area + * + * Finds the next free region that is viable for use with a given size and + * alignment. This only returns if there is a valid area to be used for this + * allocation. block->first_free is returned if the allocation request fits + * within the block to see if the request can be fulfilled prior to the contig + * hint. */ -#define pcpu_for_each_unpop_region(chunk, rs, re, start, end) \ - for ((rs) = (start), pcpu_next_unpop((chunk), &(rs), &(re), (end)); \ - (rs) < (re); \ - (rs) = (re) + 1, pcpu_next_unpop((chunk), &(rs), &(re), (end))) +static void pcpu_next_fit_region(struct pcpu_chunk *chunk, int alloc_bits, + int align, int *bit_off, int *bits) +{ + int i = pcpu_off_to_block_index(*bit_off); + int block_off = pcpu_off_to_block_off(*bit_off); + struct pcpu_block_md *block; + + *bits = 0; + for (block = chunk->md_blocks + i; i < pcpu_chunk_nr_blocks(chunk); + block++, i++) { + /* handles contig area across blocks */ + if (*bits) { + *bits += block->left_free; + if (*bits >= alloc_bits) + return; + if (block->left_free == PCPU_BITMAP_BLOCK_BITS) + continue; + } + + /* check block->contig_hint */ + *bits = ALIGN(block->contig_hint_start, align) - + block->contig_hint_start; + /* + * This uses the block offset to determine if this has been + * checked in the prior iteration. + */ + if (block->contig_hint && + block->contig_hint_start >= block_off && + block->contig_hint >= *bits + alloc_bits) { + *bits += alloc_bits + block->contig_hint_start - + block->first_free; + *bit_off = pcpu_block_off_to_off(i, block->first_free); + return; + } + + *bit_off = ALIGN(PCPU_BITMAP_BLOCK_BITS - block->right_free, + align); + *bits = PCPU_BITMAP_BLOCK_BITS - *bit_off; + *bit_off = pcpu_block_off_to_off(i, *bit_off); + if (*bits >= alloc_bits) + return; + } -#define pcpu_for_each_pop_region(chunk, rs, re, start, end) \ - for ((rs) = (start), pcpu_next_pop((chunk), &(rs), &(re), (end)); \ - (rs) < (re); \ - (rs) = (re) + 1, pcpu_next_pop((chunk), &(rs), &(re), (end))) + /* no valid offsets were found - fail condition */ + *bit_off = pcpu_chunk_map_bits(chunk); +} + +/* + * Metadata free area iterators. These perform aggregation of free areas + * based on the metadata blocks and return the offset @bit_off and size in + * bits of the free area @bits. pcpu_for_each_fit_region only returns when + * a fit is found for the allocation request. + */ +#define pcpu_for_each_md_free_region(chunk, bit_off, bits) \ + for (pcpu_next_md_free_region((chunk), &(bit_off), &(bits)); \ + (bit_off) < pcpu_chunk_map_bits((chunk)); \ + (bit_off) += (bits) + 1, \ + pcpu_next_md_free_region((chunk), &(bit_off), &(bits))) + +#define pcpu_for_each_fit_region(chunk, alloc_bits, align, bit_off, bits) \ + for (pcpu_next_fit_region((chunk), (alloc_bits), (align), &(bit_off), \ + &(bits)); \ + (bit_off) < pcpu_chunk_map_bits((chunk)); \ + (bit_off) += (bits), \ + pcpu_next_fit_region((chunk), (alloc_bits), (align), &(bit_off), \ + &(bits))) /** * pcpu_mem_zalloc - allocate memory @@ -306,38 +477,6 @@ static void pcpu_mem_free(void *ptr) } /** - * pcpu_count_occupied_pages - count the number of pages an area occupies - * @chunk: chunk of interest - * @i: index of the area in question - * - * Count the number of pages chunk's @i'th area occupies. When the area's - * start and/or end address isn't aligned to page boundary, the straddled - * page is included in the count iff the rest of the page is free. - */ -static int pcpu_count_occupied_pages(struct pcpu_chunk *chunk, int i) -{ - int off = chunk->map[i] & ~1; - int end = chunk->map[i + 1] & ~1; - - if (!PAGE_ALIGNED(off) && i > 0) { - int prev = chunk->map[i - 1]; - - if (!(prev & 1) && prev <= round_down(off, PAGE_SIZE)) - off = round_down(off, PAGE_SIZE); - } - - if (!PAGE_ALIGNED(end) && i + 1 < chunk->map_used) { - int next = chunk->map[i + 1]; - int nend = chunk->map[i + 2] & ~1; - - if (!(next & 1) && nend >= round_up(end, PAGE_SIZE)) - end = round_up(end, PAGE_SIZE); - } - - return max_t(int, PFN_DOWN(end) - PFN_UP(off), 0); -} - -/** * pcpu_chunk_relocate - put chunk in the appropriate chunk slot * @chunk: chunk of interest * @oslot: the previous slot it was on @@ -363,383 +502,706 @@ static void pcpu_chunk_relocate(struct pcpu_chunk *chunk, int oslot) } /** - * pcpu_need_to_extend - determine whether chunk area map needs to be extended + * pcpu_cnt_pop_pages- counts populated backing pages in range * @chunk: chunk of interest - * @is_atomic: the allocation context + * @bit_off: start offset + * @bits: size of area to check * - * Determine whether area map of @chunk needs to be extended. If - * @is_atomic, only the amount necessary for a new allocation is - * considered; however, async extension is scheduled if the left amount is - * low. If !@is_atomic, it aims for more empty space. Combined, this - * ensures that the map is likely to have enough available space to - * accomodate atomic allocations which can't extend maps directly. - * - * CONTEXT: - * pcpu_lock. + * Calculates the number of populated pages in the region + * [page_start, page_end). This keeps track of how many empty populated + * pages are available and decide if async work should be scheduled. * * RETURNS: - * New target map allocation length if extension is necessary, 0 - * otherwise. + * The nr of populated pages. */ -static int pcpu_need_to_extend(struct pcpu_chunk *chunk, bool is_atomic) +static inline int pcpu_cnt_pop_pages(struct pcpu_chunk *chunk, int bit_off, + int bits) { - int margin, new_alloc; - - lockdep_assert_held(&pcpu_lock); - - if (is_atomic) { - margin = 3; + int page_start = PFN_UP(bit_off * PCPU_MIN_ALLOC_SIZE); + int page_end = PFN_DOWN((bit_off + bits) * PCPU_MIN_ALLOC_SIZE); - if (chunk->map_alloc < - chunk->map_used + PCPU_ATOMIC_MAP_MARGIN_LOW) { - if (list_empty(&chunk->map_extend_list)) { - list_add_tail(&chunk->map_extend_list, - &pcpu_map_extend_chunks); - pcpu_schedule_balance_work(); - } - } - } else { - margin = PCPU_ATOMIC_MAP_MARGIN_HIGH; - } - - if (chunk->map_alloc >= chunk->map_used + margin) + if (page_start >= page_end) return 0; - new_alloc = PCPU_DFL_MAP_ALLOC; - while (new_alloc < chunk->map_used + margin) - new_alloc *= 2; - - return new_alloc; + /* + * bitmap_weight counts the number of bits set in a bitmap up to + * the specified number of bits. This is counting the populated + * pages up to page_end and then subtracting the populated pages + * up to page_start to count the populated pages in + * [page_start, page_end). + */ + return bitmap_weight(chunk->populated, page_end) - + bitmap_weight(chunk->populated, page_start); } /** - * pcpu_extend_area_map - extend area map of a chunk + * pcpu_chunk_update - updates the chunk metadata given a free area * @chunk: chunk of interest - * @new_alloc: new target allocation length of the area map + * @bit_off: chunk offset + * @bits: size of free area * - * Extend area map of @chunk to have @new_alloc entries. + * This updates the chunk's contig hint and starting offset given a free area. + * Choose the best starting offset if the contig hint is equal. + */ +static void pcpu_chunk_update(struct pcpu_chunk *chunk, int bit_off, int bits) +{ + if (bits > chunk->contig_bits) { + chunk->contig_bits_start = bit_off; + chunk->contig_bits = bits; + } else if (bits == chunk->contig_bits && chunk->contig_bits_start && + (!bit_off || + __ffs(bit_off) > __ffs(chunk->contig_bits_start))) { + /* use the start with the best alignment */ + chunk->contig_bits_start = bit_off; + } +} + +/** + * pcpu_chunk_refresh_hint - updates metadata about a chunk + * @chunk: chunk of interest * - * CONTEXT: - * Does GFP_KERNEL allocation. Grabs and releases pcpu_lock. + * Iterates over the metadata blocks to find the largest contig area. + * It also counts the populated pages and uses the delta to update the + * global count. * - * RETURNS: - * 0 on success, -errno on failure. + * Updates: + * chunk->contig_bits + * chunk->contig_bits_start + * nr_empty_pop_pages (chunk and global) */ -static int pcpu_extend_area_map(struct pcpu_chunk *chunk, int new_alloc) +static void pcpu_chunk_refresh_hint(struct pcpu_chunk *chunk) { - int *old = NULL, *new = NULL; - size_t old_size = 0, new_size = new_alloc * sizeof(new[0]); - unsigned long flags; + int bit_off, bits, nr_empty_pop_pages; - lockdep_assert_held(&pcpu_alloc_mutex); + /* clear metadata */ + chunk->contig_bits = 0; - new = pcpu_mem_zalloc(new_size); - if (!new) - return -ENOMEM; + bit_off = chunk->first_bit; + bits = nr_empty_pop_pages = 0; + pcpu_for_each_md_free_region(chunk, bit_off, bits) { + pcpu_chunk_update(chunk, bit_off, bits); - /* acquire pcpu_lock and switch to new area map */ - spin_lock_irqsave(&pcpu_lock, flags); + nr_empty_pop_pages += pcpu_cnt_pop_pages(chunk, bit_off, bits); + } - if (new_alloc <= chunk->map_alloc) - goto out_unlock; + /* + * Keep track of nr_empty_pop_pages. + * + * The chunk maintains the previous number of free pages it held, + * so the delta is used to update the global counter. The reserved + * chunk is not part of the free page count as they are populated + * at init and are special to serving reserved allocations. + */ + if (chunk != pcpu_reserved_chunk) + pcpu_nr_empty_pop_pages += + (nr_empty_pop_pages - chunk->nr_empty_pop_pages); - old_size = chunk->map_alloc * sizeof(chunk->map[0]); - old = chunk->map; + chunk->nr_empty_pop_pages = nr_empty_pop_pages; +} - memcpy(new, old, old_size); +/** + * pcpu_block_update - updates a block given a free area + * @block: block of interest + * @start: start offset in block + * @end: end offset in block + * + * Updates a block given a known free area. The region [start, end) is + * expected to be the entirety of the free area within a block. Chooses + * the best starting offset if the contig hints are equal. + */ +static void pcpu_block_update(struct pcpu_block_md *block, int start, int end) +{ + int contig = end - start; + + block->first_free = min(block->first_free, start); + if (start == 0) + block->left_free = contig; + + if (end == PCPU_BITMAP_BLOCK_BITS) + block->right_free = contig; + + if (contig > block->contig_hint) { + block->contig_hint_start = start; + block->contig_hint = contig; + } else if (block->contig_hint_start && contig == block->contig_hint && + (!start || __ffs(start) > __ffs(block->contig_hint_start))) { + /* use the start with the best alignment */ + block->contig_hint_start = start; + } +} - chunk->map_alloc = new_alloc; - chunk->map = new; - new = NULL; +/** + * pcpu_block_refresh_hint + * @chunk: chunk of interest + * @index: index of the metadata block + * + * Scans over the block beginning at first_free and updates the block + * metadata accordingly. + */ +static void pcpu_block_refresh_hint(struct pcpu_chunk *chunk, int index) +{ + struct pcpu_block_md *block = chunk->md_blocks + index; + unsigned long *alloc_map = pcpu_index_alloc_map(chunk, index); + int rs, re; /* region start, region end */ + + /* clear hints */ + block->contig_hint = 0; + block->left_free = block->right_free = 0; + + /* iterate over free areas and update the contig hints */ + pcpu_for_each_unpop_region(alloc_map, rs, re, block->first_free, + PCPU_BITMAP_BLOCK_BITS) { + pcpu_block_update(block, rs, re); + } +} -out_unlock: - spin_unlock_irqrestore(&pcpu_lock, flags); +/** + * pcpu_block_update_hint_alloc - update hint on allocation path + * @chunk: chunk of interest + * @bit_off: chunk offset + * @bits: size of request + * + * Updates metadata for the allocation path. The metadata only has to be + * refreshed by a full scan iff the chunk's contig hint is broken. Block level + * scans are required if the block's contig hint is broken. + */ +static void pcpu_block_update_hint_alloc(struct pcpu_chunk *chunk, int bit_off, + int bits) +{ + struct pcpu_block_md *s_block, *e_block, *block; + int s_index, e_index; /* block indexes of the freed allocation */ + int s_off, e_off; /* block offsets of the freed allocation */ /* - * pcpu_mem_free() might end up calling vfree() which uses - * IRQ-unsafe lock and thus can't be called under pcpu_lock. + * Calculate per block offsets. + * The calculation uses an inclusive range, but the resulting offsets + * are [start, end). e_index always points to the last block in the + * range. */ - pcpu_mem_free(old); - pcpu_mem_free(new); + s_index = pcpu_off_to_block_index(bit_off); + e_index = pcpu_off_to_block_index(bit_off + bits - 1); + s_off = pcpu_off_to_block_off(bit_off); + e_off = pcpu_off_to_block_off(bit_off + bits - 1) + 1; - return 0; + s_block = chunk->md_blocks + s_index; + e_block = chunk->md_blocks + e_index; + + /* + * Update s_block. + * block->first_free must be updated if the allocation takes its place. + * If the allocation breaks the contig_hint, a scan is required to + * restore this hint. + */ + if (s_off == s_block->first_free) + s_block->first_free = find_next_zero_bit( + pcpu_index_alloc_map(chunk, s_index), + PCPU_BITMAP_BLOCK_BITS, + s_off + bits); + + if (s_off >= s_block->contig_hint_start && + s_off < s_block->contig_hint_start + s_block->contig_hint) { + /* block contig hint is broken - scan to fix it */ + pcpu_block_refresh_hint(chunk, s_index); + } else { + /* update left and right contig manually */ + s_block->left_free = min(s_block->left_free, s_off); + if (s_index == e_index) + s_block->right_free = min_t(int, s_block->right_free, + PCPU_BITMAP_BLOCK_BITS - e_off); + else + s_block->right_free = 0; + } + + /* + * Update e_block. + */ + if (s_index != e_index) { + /* + * When the allocation is across blocks, the end is along + * the left part of the e_block. + */ + e_block->first_free = find_next_zero_bit( + pcpu_index_alloc_map(chunk, e_index), + PCPU_BITMAP_BLOCK_BITS, e_off); + + if (e_off == PCPU_BITMAP_BLOCK_BITS) { + /* reset the block */ + e_block++; + } else { + if (e_off > e_block->contig_hint_start) { + /* contig hint is broken - scan to fix it */ + pcpu_block_refresh_hint(chunk, e_index); + } else { + e_block->left_free = 0; + e_block->right_free = + min_t(int, e_block->right_free, + PCPU_BITMAP_BLOCK_BITS - e_off); + } + } + + /* update in-between md_blocks */ + for (block = s_block + 1; block < e_block; block++) { + block->contig_hint = 0; + block->left_free = 0; + block->right_free = 0; + } + } + + /* + * The only time a full chunk scan is required is if the chunk + * contig hint is broken. Otherwise, it means a smaller space + * was used and therefore the chunk contig hint is still correct. + */ + if (bit_off >= chunk->contig_bits_start && + bit_off < chunk->contig_bits_start + chunk->contig_bits) + pcpu_chunk_refresh_hint(chunk); } /** - * pcpu_fit_in_area - try to fit the requested allocation in a candidate area - * @chunk: chunk the candidate area belongs to - * @off: the offset to the start of the candidate area - * @this_size: the size of the candidate area - * @size: the size of the target allocation - * @align: the alignment of the target allocation - * @pop_only: only allocate from already populated region - * - * We're trying to allocate @size bytes aligned at @align. @chunk's area - * at @off sized @this_size is a candidate. This function determines - * whether the target allocation fits in the candidate area and returns the - * number of bytes to pad after @off. If the target area doesn't fit, -1 - * is returned. - * - * If @pop_only is %true, this function only considers the already - * populated part of the candidate area. + * pcpu_block_update_hint_free - updates the block hints on the free path + * @chunk: chunk of interest + * @bit_off: chunk offset + * @bits: size of request + * + * Updates metadata for the allocation path. This avoids a blind block + * refresh by making use of the block contig hints. If this fails, it scans + * forward and backward to determine the extent of the free area. This is + * capped at the boundary of blocks. + * + * A chunk update is triggered if a page becomes free, a block becomes free, + * or the free spans across blocks. This tradeoff is to minimize iterating + * over the block metadata to update chunk->contig_bits. chunk->contig_bits + * may be off by up to a page, but it will never be more than the available + * space. If the contig hint is contained in one block, it will be accurate. */ -static int pcpu_fit_in_area(struct pcpu_chunk *chunk, int off, int this_size, - int size, int align, bool pop_only) +static void pcpu_block_update_hint_free(struct pcpu_chunk *chunk, int bit_off, + int bits) { - int cand_off = off; - - while (true) { - int head = ALIGN(cand_off, align) - off; - int page_start, page_end, rs, re; + struct pcpu_block_md *s_block, *e_block, *block; + int s_index, e_index; /* block indexes of the freed allocation */ + int s_off, e_off; /* block offsets of the freed allocation */ + int start, end; /* start and end of the whole free area */ - if (this_size < head + size) - return -1; + /* + * Calculate per block offsets. + * The calculation uses an inclusive range, but the resulting offsets + * are [start, end). e_index always points to the last block in the + * range. + */ + s_index = pcpu_off_to_block_index(bit_off); + e_index = pcpu_off_to_block_index(bit_off + bits - 1); + s_off = pcpu_off_to_block_off(bit_off); + e_off = pcpu_off_to_block_off(bit_off + bits - 1) + 1; - if (!pop_only) - return head; + s_block = chunk->md_blocks + s_index; + e_block = chunk->md_blocks + e_index; + /* + * Check if the freed area aligns with the block->contig_hint. + * If it does, then the scan to find the beginning/end of the + * larger free area can be avoided. + * + * start and end refer to beginning and end of the free area + * within each their respective blocks. This is not necessarily + * the entire free area as it may span blocks past the beginning + * or end of the block. + */ + start = s_off; + if (s_off == s_block->contig_hint + s_block->contig_hint_start) { + start = s_block->contig_hint_start; + } else { /* - * If the first unpopulated page is beyond the end of the - * allocation, the whole allocation is populated; - * otherwise, retry from the end of the unpopulated area. + * Scan backwards to find the extent of the free area. + * find_last_bit returns the starting bit, so if the start bit + * is returned, that means there was no last bit and the + * remainder of the chunk is free. */ - page_start = PFN_DOWN(head + off); - page_end = PFN_UP(head + off + size); - - rs = page_start; - pcpu_next_unpop(chunk, &rs, &re, PFN_UP(off + this_size)); - if (rs >= page_end) - return head; - cand_off = re * PAGE_SIZE; + int l_bit = find_last_bit(pcpu_index_alloc_map(chunk, s_index), + start); + start = (start == l_bit) ? 0 : l_bit + 1; + } + + end = e_off; + if (e_off == e_block->contig_hint_start) + end = e_block->contig_hint_start + e_block->contig_hint; + else + end = find_next_bit(pcpu_index_alloc_map(chunk, e_index), + PCPU_BITMAP_BLOCK_BITS, end); + + /* update s_block */ + e_off = (s_index == e_index) ? end : PCPU_BITMAP_BLOCK_BITS; + pcpu_block_update(s_block, start, e_off); + + /* freeing in the same block */ + if (s_index != e_index) { + /* update e_block */ + pcpu_block_update(e_block, 0, end); + + /* reset md_blocks in the middle */ + for (block = s_block + 1; block < e_block; block++) { + block->first_free = 0; + block->contig_hint_start = 0; + block->contig_hint = PCPU_BITMAP_BLOCK_BITS; + block->left_free = PCPU_BITMAP_BLOCK_BITS; + block->right_free = PCPU_BITMAP_BLOCK_BITS; + } } + + /* + * Refresh chunk metadata when the free makes a page free, a block + * free, or spans across blocks. The contig hint may be off by up to + * a page, but if the hint is contained in a block, it will be accurate + * with the else condition below. + */ + if ((ALIGN_DOWN(end, min(PCPU_BITS_PER_PAGE, PCPU_BITMAP_BLOCK_BITS)) > + ALIGN(start, min(PCPU_BITS_PER_PAGE, PCPU_BITMAP_BLOCK_BITS))) || + s_index != e_index) + pcpu_chunk_refresh_hint(chunk); + else + pcpu_chunk_update(chunk, pcpu_block_off_to_off(s_index, start), + s_block->contig_hint); } /** - * pcpu_alloc_area - allocate area from a pcpu_chunk + * pcpu_is_populated - determines if the region is populated * @chunk: chunk of interest - * @size: wanted size in bytes - * @align: wanted align - * @pop_only: allocate only from the populated area - * @occ_pages_p: out param for the number of pages the area occupies - * - * Try to allocate @size bytes area aligned at @align from @chunk. - * Note that this function only allocates the offset. It doesn't - * populate or map the area. + * @bit_off: chunk offset + * @bits: size of area + * @next_off: return value for the next offset to start searching * - * @chunk->map must have at least two free slots. + * For atomic allocations, check if the backing pages are populated. * - * CONTEXT: - * pcpu_lock. + * RETURNS: + * Bool if the backing pages are populated. + * next_index is to skip over unpopulated blocks in pcpu_find_block_fit. + */ +static bool pcpu_is_populated(struct pcpu_chunk *chunk, int bit_off, int bits, + int *next_off) +{ + int page_start, page_end, rs, re; + + page_start = PFN_DOWN(bit_off * PCPU_MIN_ALLOC_SIZE); + page_end = PFN_UP((bit_off + bits) * PCPU_MIN_ALLOC_SIZE); + + rs = page_start; + pcpu_next_unpop(chunk->populated, &rs, &re, page_end); + if (rs >= page_end) + return true; + + *next_off = re * PAGE_SIZE / PCPU_MIN_ALLOC_SIZE; + return false; +} + +/** + * pcpu_find_block_fit - finds the block index to start searching + * @chunk: chunk of interest + * @alloc_bits: size of request in allocation units + * @align: alignment of area (max PAGE_SIZE bytes) + * @pop_only: use populated regions only + * + * Given a chunk and an allocation spec, find the offset to begin searching + * for a free region. This iterates over the bitmap metadata blocks to + * find an offset that will be guaranteed to fit the requirements. It is + * not quite first fit as if the allocation does not fit in the contig hint + * of a block or chunk, it is skipped. This errs on the side of caution + * to prevent excess iteration. Poor alignment can cause the allocator to + * skip over blocks and chunks that have valid free areas. * * RETURNS: - * Allocated offset in @chunk on success, -1 if no matching area is - * found. + * The offset in the bitmap to begin searching. + * -1 if no offset is found. */ -static int pcpu_alloc_area(struct pcpu_chunk *chunk, int size, int align, - bool pop_only, int *occ_pages_p) +static int pcpu_find_block_fit(struct pcpu_chunk *chunk, int alloc_bits, + size_t align, bool pop_only) { - int oslot = pcpu_chunk_slot(chunk); - int max_contig = 0; - int i, off; - bool seen_free = false; - int *p; - - for (i = chunk->first_free, p = chunk->map + i; i < chunk->map_used; i++, p++) { - int head, tail; - int this_size; - - off = *p; - if (off & 1) - continue; + int bit_off, bits, next_off; - this_size = (p[1] & ~1) - off; + /* + * Check to see if the allocation can fit in the chunk's contig hint. + * This is an optimization to prevent scanning by assuming if it + * cannot fit in the global hint, there is memory pressure and creating + * a new chunk would happen soon. + */ + bit_off = ALIGN(chunk->contig_bits_start, align) - + chunk->contig_bits_start; + if (bit_off + alloc_bits > chunk->contig_bits) + return -1; + + bit_off = chunk->first_bit; + bits = 0; + pcpu_for_each_fit_region(chunk, alloc_bits, align, bit_off, bits) { + if (!pop_only || pcpu_is_populated(chunk, bit_off, bits, + &next_off)) + break; - head = pcpu_fit_in_area(chunk, off, this_size, size, align, - pop_only); - if (head < 0) { - if (!seen_free) { - chunk->first_free = i; - seen_free = true; - } - max_contig = max(this_size, max_contig); - continue; - } + bit_off = next_off; + bits = 0; + } - /* - * If head is small or the previous block is free, - * merge'em. Note that 'small' is defined as smaller - * than sizeof(int), which is very small but isn't too - * uncommon for percpu allocations. - */ - if (head && (head < sizeof(int) || !(p[-1] & 1))) { - *p = off += head; - if (p[-1] & 1) - chunk->free_size -= head; - else - max_contig = max(*p - p[-1], max_contig); - this_size -= head; - head = 0; - } + if (bit_off == pcpu_chunk_map_bits(chunk)) + return -1; - /* if tail is small, just keep it around */ - tail = this_size - head - size; - if (tail < sizeof(int)) { - tail = 0; - size = this_size - head; - } + return bit_off; +} - /* split if warranted */ - if (head || tail) { - int nr_extra = !!head + !!tail; - - /* insert new subblocks */ - memmove(p + nr_extra + 1, p + 1, - sizeof(chunk->map[0]) * (chunk->map_used - i)); - chunk->map_used += nr_extra; - - if (head) { - if (!seen_free) { - chunk->first_free = i; - seen_free = true; - } - *++p = off += head; - ++i; - max_contig = max(head, max_contig); - } - if (tail) { - p[1] = off + size; - max_contig = max(tail, max_contig); - } - } +/** + * pcpu_alloc_area - allocates an area from a pcpu_chunk + * @chunk: chunk of interest + * @alloc_bits: size of request in allocation units + * @align: alignment of area (max PAGE_SIZE) + * @start: bit_off to start searching + * + * This function takes in a @start offset to begin searching to fit an + * allocation of @alloc_bits with alignment @align. It needs to scan + * the allocation map because if it fits within the block's contig hint, + * @start will be block->first_free. This is an attempt to fill the + * allocation prior to breaking the contig hint. The allocation and + * boundary maps are updated accordingly if it confirms a valid + * free area. + * + * RETURNS: + * Allocated addr offset in @chunk on success. + * -1 if no matching area is found. + */ +static int pcpu_alloc_area(struct pcpu_chunk *chunk, int alloc_bits, + size_t align, int start) +{ + size_t align_mask = (align) ? (align - 1) : 0; + int bit_off, end, oslot; - if (!seen_free) - chunk->first_free = i + 1; + lockdep_assert_held(&pcpu_lock); - /* update hint and mark allocated */ - if (i + 1 == chunk->map_used) - chunk->contig_hint = max_contig; /* fully scanned */ - else - chunk->contig_hint = max(chunk->contig_hint, - max_contig); + oslot = pcpu_chunk_slot(chunk); - chunk->free_size -= size; - *p |= 1; + /* + * Search to find a fit. + */ + end = start + alloc_bits + PCPU_BITMAP_BLOCK_BITS; + bit_off = bitmap_find_next_zero_area(chunk->alloc_map, end, start, + alloc_bits, align_mask); + if (bit_off >= end) + return -1; - *occ_pages_p = pcpu_count_occupied_pages(chunk, i); - pcpu_chunk_relocate(chunk, oslot); - return off; - } + /* update alloc map */ + bitmap_set(chunk->alloc_map, bit_off, alloc_bits); + + /* update boundary map */ + set_bit(bit_off, chunk->bound_map); + bitmap_clear(chunk->bound_map, bit_off + 1, alloc_bits - 1); + set_bit(bit_off + alloc_bits, chunk->bound_map); + + chunk->free_bytes -= alloc_bits * PCPU_MIN_ALLOC_SIZE; + + /* update first free bit */ + if (bit_off == chunk->first_bit) + chunk->first_bit = find_next_zero_bit( + chunk->alloc_map, + pcpu_chunk_map_bits(chunk), + bit_off + alloc_bits); + + pcpu_block_update_hint_alloc(chunk, bit_off, alloc_bits); - chunk->contig_hint = max_contig; /* fully scanned */ pcpu_chunk_relocate(chunk, oslot); - /* tell the upper layer that this chunk has no matching area */ - return -1; + return bit_off * PCPU_MIN_ALLOC_SIZE; } /** - * pcpu_free_area - free area to a pcpu_chunk + * pcpu_free_area - frees the corresponding offset * @chunk: chunk of interest - * @freeme: offset of area to free - * @occ_pages_p: out param for the number of pages the area occupies - * - * Free area starting from @freeme to @chunk. Note that this function - * only modifies the allocation map. It doesn't depopulate or unmap - * the area. + * @off: addr offset into chunk * - * CONTEXT: - * pcpu_lock. + * This function determines the size of an allocation to free using + * the boundary bitmap and clears the allocation map. */ -static void pcpu_free_area(struct pcpu_chunk *chunk, int freeme, - int *occ_pages_p) +static void pcpu_free_area(struct pcpu_chunk *chunk, int off) { - int oslot = pcpu_chunk_slot(chunk); - int off = 0; - unsigned i, j; - int to_free = 0; - int *p; + int bit_off, bits, end, oslot; lockdep_assert_held(&pcpu_lock); pcpu_stats_area_dealloc(chunk); - freeme |= 1; /* we are searching for <given offset, in use> pair */ - - i = 0; - j = chunk->map_used; - while (i != j) { - unsigned k = (i + j) / 2; - off = chunk->map[k]; - if (off < freeme) - i = k + 1; - else if (off > freeme) - j = k; - else - i = j = k; + oslot = pcpu_chunk_slot(chunk); + + bit_off = off / PCPU_MIN_ALLOC_SIZE; + + /* find end index */ + end = find_next_bit(chunk->bound_map, pcpu_chunk_map_bits(chunk), + bit_off + 1); + bits = end - bit_off; + bitmap_clear(chunk->alloc_map, bit_off, bits); + + /* update metadata */ + chunk->free_bytes += bits * PCPU_MIN_ALLOC_SIZE; + + /* update first free bit */ + chunk->first_bit = min(chunk->first_bit, bit_off); + + pcpu_block_update_hint_free(chunk, bit_off, bits); + + pcpu_chunk_relocate(chunk, oslot); +} + +static void pcpu_init_md_blocks(struct pcpu_chunk *chunk) +{ + struct pcpu_block_md *md_block; + + for (md_block = chunk->md_blocks; + md_block != chunk->md_blocks + pcpu_chunk_nr_blocks(chunk); + md_block++) { + md_block->contig_hint = PCPU_BITMAP_BLOCK_BITS; + md_block->left_free = PCPU_BITMAP_BLOCK_BITS; + md_block->right_free = PCPU_BITMAP_BLOCK_BITS; } - BUG_ON(off != freeme); +} - if (i < chunk->first_free) - chunk->first_free = i; +/** + * pcpu_alloc_first_chunk - creates chunks that serve the first chunk + * @tmp_addr: the start of the region served + * @map_size: size of the region served + * + * This is responsible for creating the chunks that serve the first chunk. The + * base_addr is page aligned down of @tmp_addr while the region end is page + * aligned up. Offsets are kept track of to determine the region served. All + * this is done to appease the bitmap allocator in avoiding partial blocks. + * + * RETURNS: + * Chunk serving the region at @tmp_addr of @map_size. + */ +static struct pcpu_chunk * __init pcpu_alloc_first_chunk(unsigned long tmp_addr, + int map_size) +{ + struct pcpu_chunk *chunk; + unsigned long aligned_addr, lcm_align; + int start_offset, offset_bits, region_size, region_bits; - p = chunk->map + i; - *p = off &= ~1; - chunk->free_size += (p[1] & ~1) - off; + /* region calculations */ + aligned_addr = tmp_addr & PAGE_MASK; - *occ_pages_p = pcpu_count_occupied_pages(chunk, i); + start_offset = tmp_addr - aligned_addr; - /* merge with next? */ - if (!(p[1] & 1)) - to_free++; - /* merge with previous? */ - if (i > 0 && !(p[-1] & 1)) { - to_free++; - i--; - p--; + /* + * Align the end of the region with the LCM of PAGE_SIZE and + * PCPU_BITMAP_BLOCK_SIZE. One of these constants is a multiple of + * the other. + */ + lcm_align = lcm(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE); + region_size = ALIGN(start_offset + map_size, lcm_align); + + /* allocate chunk */ + chunk = memblock_virt_alloc(sizeof(struct pcpu_chunk) + + BITS_TO_LONGS(region_size >> PAGE_SHIFT), + 0); + + INIT_LIST_HEAD(&chunk->list); + + chunk->base_addr = (void *)aligned_addr; + chunk->start_offset = start_offset; + chunk->end_offset = region_size - chunk->start_offset - map_size; + + chunk->nr_pages = region_size >> PAGE_SHIFT; + region_bits = pcpu_chunk_map_bits(chunk); + + chunk->alloc_map = memblock_virt_alloc(BITS_TO_LONGS(region_bits) * + sizeof(chunk->alloc_map[0]), 0); + chunk->bound_map = memblock_virt_alloc(BITS_TO_LONGS(region_bits + 1) * + sizeof(chunk->bound_map[0]), 0); + chunk->md_blocks = memblock_virt_alloc(pcpu_chunk_nr_blocks(chunk) * + sizeof(chunk->md_blocks[0]), 0); + pcpu_init_md_blocks(chunk); + + /* manage populated page bitmap */ + chunk->immutable = true; + bitmap_fill(chunk->populated, chunk->nr_pages); + chunk->nr_populated = chunk->nr_pages; + chunk->nr_empty_pop_pages = + pcpu_cnt_pop_pages(chunk, start_offset / PCPU_MIN_ALLOC_SIZE, + map_size / PCPU_MIN_ALLOC_SIZE); + + chunk->contig_bits = map_size / PCPU_MIN_ALLOC_SIZE; + chunk->free_bytes = map_size; + + if (chunk->start_offset) { + /* hide the beginning of the bitmap */ + offset_bits = chunk->start_offset / PCPU_MIN_ALLOC_SIZE; + bitmap_set(chunk->alloc_map, 0, offset_bits); + set_bit(0, chunk->bound_map); + set_bit(offset_bits, chunk->bound_map); + + chunk->first_bit = offset_bits; + + pcpu_block_update_hint_alloc(chunk, 0, offset_bits); } - if (to_free) { - chunk->map_used -= to_free; - memmove(p + 1, p + 1 + to_free, - (chunk->map_used - i) * sizeof(chunk->map[0])); + + if (chunk->end_offset) { + /* hide the end of the bitmap */ + offset_bits = chunk->end_offset / PCPU_MIN_ALLOC_SIZE; + bitmap_set(chunk->alloc_map, + pcpu_chunk_map_bits(chunk) - offset_bits, + offset_bits); + set_bit((start_offset + map_size) / PCPU_MIN_ALLOC_SIZE, + chunk->bound_map); + set_bit(region_bits, chunk->bound_map); + + pcpu_block_update_hint_alloc(chunk, pcpu_chunk_map_bits(chunk) + - offset_bits, offset_bits); } - chunk->contig_hint = max(chunk->map[i + 1] - chunk->map[i] - 1, chunk->contig_hint); - pcpu_chunk_relocate(chunk, oslot); + return chunk; } static struct pcpu_chunk *pcpu_alloc_chunk(void) { struct pcpu_chunk *chunk; + int region_bits; chunk = pcpu_mem_zalloc(pcpu_chunk_struct_size); if (!chunk) return NULL; - chunk->map = pcpu_mem_zalloc(PCPU_DFL_MAP_ALLOC * - sizeof(chunk->map[0])); - if (!chunk->map) { - pcpu_mem_free(chunk); - return NULL; - } + INIT_LIST_HEAD(&chunk->list); + chunk->nr_pages = pcpu_unit_pages; + region_bits = pcpu_chunk_map_bits(chunk); - chunk->map_alloc = PCPU_DFL_MAP_ALLOC; - chunk->map[0] = 0; - chunk->map[1] = pcpu_unit_size | 1; - chunk->map_used = 1; - chunk->has_reserved = false; + chunk->alloc_map = pcpu_mem_zalloc(BITS_TO_LONGS(region_bits) * + sizeof(chunk->alloc_map[0])); + if (!chunk->alloc_map) + goto alloc_map_fail; - INIT_LIST_HEAD(&chunk->list); - INIT_LIST_HEAD(&chunk->map_extend_list); - chunk->free_size = pcpu_unit_size; - chunk->contig_hint = pcpu_unit_size; + chunk->bound_map = pcpu_mem_zalloc(BITS_TO_LONGS(region_bits + 1) * + sizeof(chunk->bound_map[0])); + if (!chunk->bound_map) + goto bound_map_fail; + + chunk->md_blocks = pcpu_mem_zalloc(pcpu_chunk_nr_blocks(chunk) * + sizeof(chunk->md_blocks[0])); + if (!chunk->md_blocks) + goto md_blocks_fail; + + pcpu_init_md_blocks(chunk); + + /* init metadata */ + chunk->contig_bits = region_bits; + chunk->free_bytes = chunk->nr_pages * PAGE_SIZE; return chunk; + +md_blocks_fail: + pcpu_mem_free(chunk->bound_map); +bound_map_fail: + pcpu_mem_free(chunk->alloc_map); +alloc_map_fail: + pcpu_mem_free(chunk); + + return NULL; } static void pcpu_free_chunk(struct pcpu_chunk *chunk) { if (!chunk) return; - pcpu_mem_free(chunk->map); + pcpu_mem_free(chunk->bound_map); + pcpu_mem_free(chunk->alloc_map); pcpu_mem_free(chunk); } @@ -748,13 +1210,17 @@ static void pcpu_free_chunk(struct pcpu_chunk *chunk) * @chunk: pcpu_chunk which got populated * @page_start: the start page * @page_end: the end page + * @for_alloc: if this is to populate for allocation * * Pages in [@page_start,@page_end) have been populated to @chunk. Update * the bookkeeping information accordingly. Must be called after each * successful population. + * + * If this is @for_alloc, do not increment pcpu_nr_empty_pop_pages because it + * is to serve an allocation in that area. */ -static void pcpu_chunk_populated(struct pcpu_chunk *chunk, - int page_start, int page_end) +static void pcpu_chunk_populated(struct pcpu_chunk *chunk, int page_start, + int page_end, bool for_alloc) { int nr = page_end - page_start; @@ -762,7 +1228,11 @@ static void pcpu_chunk_populated(struct pcpu_chunk *chunk, bitmap_set(chunk->populated, page_start, nr); chunk->nr_populated += nr; - pcpu_nr_empty_pop_pages += nr; + + if (!for_alloc) { + chunk->nr_empty_pop_pages += nr; + pcpu_nr_empty_pop_pages += nr; + } } /** @@ -784,6 +1254,7 @@ static void pcpu_chunk_depopulated(struct pcpu_chunk *chunk, bitmap_clear(chunk->populated, page_start, nr); chunk->nr_populated -= nr; + chunk->nr_empty_pop_pages -= nr; pcpu_nr_empty_pop_pages -= nr; } @@ -819,18 +1290,21 @@ static int __init pcpu_verify_alloc_info(const struct pcpu_alloc_info *ai); * pcpu_chunk_addr_search - determine chunk containing specified address * @addr: address for which the chunk needs to be determined. * + * This is an internal function that handles all but static allocations. + * Static percpu address values should never be passed into the allocator. + * * RETURNS: * The address of the found chunk. */ static struct pcpu_chunk *pcpu_chunk_addr_search(void *addr) { - /* is it in the first chunk? */ - if (pcpu_addr_in_first_chunk(addr)) { - /* is it in the reserved area? */ - if (pcpu_addr_in_reserved_chunk(addr)) - return pcpu_reserved_chunk; + /* is it in the dynamic region (first chunk)? */ + if (pcpu_addr_in_chunk(pcpu_first_chunk, addr)) return pcpu_first_chunk; - } + + /* is it in the reserved region? */ + if (pcpu_addr_in_chunk(pcpu_reserved_chunk, addr)) + return pcpu_reserved_chunk; /* * The address is relative to unit0 which might be unused and @@ -863,19 +1337,23 @@ static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved, struct pcpu_chunk *chunk; const char *err; bool is_atomic = (gfp & GFP_KERNEL) != GFP_KERNEL; - int occ_pages = 0; - int slot, off, new_alloc, cpu, ret; + int slot, off, cpu, ret; unsigned long flags; void __percpu *ptr; + size_t bits, bit_align; /* - * We want the lowest bit of offset available for in-use/free - * indicator, so force >= 16bit alignment and make size even. + * There is now a minimum allocation size of PCPU_MIN_ALLOC_SIZE, + * therefore alignment must be a minimum of that many bytes. + * An allocation may have internal fragmentation from rounding up + * of up to PCPU_MIN_ALLOC_SIZE - 1 bytes. */ - if (unlikely(align < 2)) - align = 2; + if (unlikely(align < PCPU_MIN_ALLOC_SIZE)) + align = PCPU_MIN_ALLOC_SIZE; - size = ALIGN(size, 2); + size = ALIGN(size, PCPU_MIN_ALLOC_SIZE); + bits = size >> PCPU_MIN_ALLOC_SHIFT; + bit_align = align >> PCPU_MIN_ALLOC_SHIFT; if (unlikely(!size || size > PCPU_MIN_UNIT_SIZE || align > PAGE_SIZE || !is_power_of_2(align))) { @@ -893,23 +1371,13 @@ static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved, if (reserved && pcpu_reserved_chunk) { chunk = pcpu_reserved_chunk; - if (size > chunk->contig_hint) { + off = pcpu_find_block_fit(chunk, bits, bit_align, is_atomic); + if (off < 0) { err = "alloc from reserved chunk failed"; goto fail_unlock; } - while ((new_alloc = pcpu_need_to_extend(chunk, is_atomic))) { - spin_unlock_irqrestore(&pcpu_lock, flags); - if (is_atomic || - pcpu_extend_area_map(chunk, new_alloc) < 0) { - err = "failed to extend area map of reserved chunk"; - goto fail; - } - spin_lock_irqsave(&pcpu_lock, flags); - } - - off = pcpu_alloc_area(chunk, size, align, is_atomic, - &occ_pages); + off = pcpu_alloc_area(chunk, bits, bit_align, off); if (off >= 0) goto area_found; @@ -921,31 +1389,15 @@ restart: /* search through normal chunks */ for (slot = pcpu_size_to_slot(size); slot < pcpu_nr_slots; slot++) { list_for_each_entry(chunk, &pcpu_slot[slot], list) { - if (size > chunk->contig_hint) + off = pcpu_find_block_fit(chunk, bits, bit_align, + is_atomic); + if (off < 0) continue; - new_alloc = pcpu_need_to_extend(chunk, is_atomic); - if (new_alloc) { - if (is_atomic) - continue; - spin_unlock_irqrestore(&pcpu_lock, flags); - if (pcpu_extend_area_map(chunk, - new_alloc) < 0) { - err = "failed to extend area map"; - goto fail; - } - spin_lock_irqsave(&pcpu_lock, flags); - /* - * pcpu_lock has been dropped, need to - * restart cpu_slot list walking. - */ - goto restart; - } - - off = pcpu_alloc_area(chunk, size, align, is_atomic, - &occ_pages); + off = pcpu_alloc_area(chunk, bits, bit_align, off); if (off >= 0) goto area_found; + } } @@ -987,30 +1439,25 @@ area_found: page_start = PFN_DOWN(off); page_end = PFN_UP(off + size); - pcpu_for_each_unpop_region(chunk, rs, re, page_start, page_end) { + pcpu_for_each_unpop_region(chunk->populated, rs, re, + page_start, page_end) { WARN_ON(chunk->immutable); ret = pcpu_populate_chunk(chunk, rs, re); spin_lock_irqsave(&pcpu_lock, flags); if (ret) { - pcpu_free_area(chunk, off, &occ_pages); + pcpu_free_area(chunk, off); err = "failed to populate"; goto fail_unlock; } - pcpu_chunk_populated(chunk, rs, re); + pcpu_chunk_populated(chunk, rs, re, true); spin_unlock_irqrestore(&pcpu_lock, flags); } mutex_unlock(&pcpu_alloc_mutex); } - if (chunk != pcpu_reserved_chunk) { - spin_lock_irqsave(&pcpu_lock, flags); - pcpu_nr_empty_pop_pages -= occ_pages; - spin_unlock_irqrestore(&pcpu_lock, flags); - } - if (pcpu_nr_empty_pop_pages < PCPU_EMPTY_POP_PAGES_LOW) pcpu_schedule_balance_work(); @@ -1128,7 +1575,6 @@ static void pcpu_balance_workfn(struct work_struct *work) if (chunk == list_first_entry(free_head, struct pcpu_chunk, list)) continue; - list_del_init(&chunk->map_extend_list); list_move(&chunk->list, &to_free); } @@ -1137,7 +1583,8 @@ static void pcpu_balance_workfn(struct work_struct *work) list_for_each_entry_safe(chunk, next, &to_free, list) { int rs, re; - pcpu_for_each_pop_region(chunk, rs, re, 0, pcpu_unit_pages) { + pcpu_for_each_pop_region(chunk->populated, rs, re, 0, + chunk->nr_pages) { pcpu_depopulate_chunk(chunk, rs, re); spin_lock_irq(&pcpu_lock); pcpu_chunk_depopulated(chunk, rs, re); @@ -1146,25 +1593,6 @@ static void pcpu_balance_workfn(struct work_struct *work) pcpu_destroy_chunk(chunk); } - /* service chunks which requested async area map extension */ - do { - int new_alloc = 0; - - spin_lock_irq(&pcpu_lock); - - chunk = list_first_entry_or_null(&pcpu_map_extend_chunks, - struct pcpu_chunk, map_extend_list); - if (chunk) { - list_del_init(&chunk->map_extend_list); - new_alloc = pcpu_need_to_extend(chunk, false); - } - - spin_unlock_irq(&pcpu_lock); - - if (new_alloc) - pcpu_extend_area_map(chunk, new_alloc); - } while (chunk); - /* * Ensure there are certain number of free populated pages for * atomic allocs. Fill up from the most packed so that atomic @@ -1194,7 +1622,7 @@ retry_pop: spin_lock_irq(&pcpu_lock); list_for_each_entry(chunk, &pcpu_slot[slot], list) { - nr_unpop = pcpu_unit_pages - chunk->nr_populated; + nr_unpop = chunk->nr_pages - chunk->nr_populated; if (nr_unpop) break; } @@ -1204,14 +1632,15 @@ retry_pop: continue; /* @chunk can't go away while pcpu_alloc_mutex is held */ - pcpu_for_each_unpop_region(chunk, rs, re, 0, pcpu_unit_pages) { + pcpu_for_each_unpop_region(chunk->populated, rs, re, 0, + chunk->nr_pages) { int nr = min(re - rs, nr_to_pop); ret = pcpu_populate_chunk(chunk, rs, rs + nr); if (!ret) { nr_to_pop -= nr; spin_lock_irq(&pcpu_lock); - pcpu_chunk_populated(chunk, rs, rs + nr); + pcpu_chunk_populated(chunk, rs, rs + nr, false); spin_unlock_irq(&pcpu_lock); } else { nr_to_pop = 0; @@ -1250,7 +1679,7 @@ void free_percpu(void __percpu *ptr) void *addr; struct pcpu_chunk *chunk; unsigned long flags; - int off, occ_pages; + int off; if (!ptr) return; @@ -1264,13 +1693,10 @@ void free_percpu(void __percpu *ptr) chunk = pcpu_chunk_addr_search(addr); off = addr - chunk->base_addr; - pcpu_free_area(chunk, off, &occ_pages); - - if (chunk != pcpu_reserved_chunk) - pcpu_nr_empty_pop_pages += occ_pages; + pcpu_free_area(chunk, off); /* if there are more than one fully free chunks, wake up grim reaper */ - if (chunk->free_size == pcpu_unit_size) { + if (chunk->free_bytes == pcpu_unit_size) { struct pcpu_chunk *pos; list_for_each_entry(pos, &pcpu_slot[pcpu_nr_slots - 1], list) @@ -1361,10 +1787,16 @@ phys_addr_t per_cpu_ptr_to_phys(void *addr) * The following test on unit_low/high isn't strictly * necessary but will speed up lookups of addresses which * aren't in the first chunk. + * + * The address check is against full chunk sizes. pcpu_base_addr + * points to the beginning of the first chunk including the + * static region. Assumes good intent as the first chunk may + * not be full (ie. < pcpu_unit_pages in size). */ - first_low = pcpu_chunk_addr(pcpu_first_chunk, pcpu_low_unit_cpu, 0); - first_high = pcpu_chunk_addr(pcpu_first_chunk, pcpu_high_unit_cpu, - pcpu_unit_pages); + first_low = (unsigned long)pcpu_base_addr + + pcpu_unit_page_offset(pcpu_low_unit_cpu, 0); + first_high = (unsigned long)pcpu_base_addr + + pcpu_unit_page_offset(pcpu_high_unit_cpu, pcpu_unit_pages); if ((unsigned long)addr >= first_low && (unsigned long)addr < first_high) { for_each_possible_cpu(cpu) { @@ -1546,12 +1978,13 @@ static void pcpu_dump_alloc_info(const char *lvl, * The caller should have mapped the first chunk at @base_addr and * copied static data to each unit. * - * If the first chunk ends up with both reserved and dynamic areas, it - * is served by two chunks - one to serve the core static and reserved - * areas and the other for the dynamic area. They share the same vm - * and page map but uses different area allocation map to stay away - * from each other. The latter chunk is circulated in the chunk slots - * and available for dynamic allocation like any other chunks. + * The first chunk will always contain a static and a dynamic region. + * However, the static region is not managed by any chunk. If the first + * chunk also contains a reserved region, it is served by two chunks - + * one for the reserved region and one for the dynamic region. They + * share the same vm, but use offset regions in the area allocation map. + * The chunk serving the dynamic region is circulated in the chunk slots + * and available for dynamic allocation like any other chunk. * * RETURNS: * 0 on success, -errno on failure. @@ -1559,17 +1992,17 @@ static void pcpu_dump_alloc_info(const char *lvl, int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai, void *base_addr) { - static int smap[PERCPU_DYNAMIC_EARLY_SLOTS] __initdata; - static int dmap[PERCPU_DYNAMIC_EARLY_SLOTS] __initdata; - size_t dyn_size = ai->dyn_size; - size_t size_sum = ai->static_size + ai->reserved_size + dyn_size; - struct pcpu_chunk *schunk, *dchunk = NULL; + size_t size_sum = ai->static_size + ai->reserved_size + ai->dyn_size; + size_t static_size, dyn_size; + struct pcpu_chunk *chunk; unsigned long *group_offsets; size_t *group_sizes; unsigned long *unit_off; unsigned int cpu; int *unit_map; int group, unit, i; + int map_size; + unsigned long tmp_addr; #define PCPU_SETUP_BUG_ON(cond) do { \ if (unlikely(cond)) { \ @@ -1592,7 +2025,12 @@ int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai, PCPU_SETUP_BUG_ON(ai->unit_size < size_sum); PCPU_SETUP_BUG_ON(offset_in_page(ai->unit_size)); PCPU_SETUP_BUG_ON(ai->unit_size < PCPU_MIN_UNIT_SIZE); + PCPU_SETUP_BUG_ON(!IS_ALIGNED(ai->unit_size, PCPU_BITMAP_BLOCK_SIZE)); PCPU_SETUP_BUG_ON(ai->dyn_size < PERCPU_DYNAMIC_EARLY_SIZE); + PCPU_SETUP_BUG_ON(!ai->dyn_size); + PCPU_SETUP_BUG_ON(!IS_ALIGNED(ai->reserved_size, PCPU_MIN_ALLOC_SIZE)); + PCPU_SETUP_BUG_ON(!(IS_ALIGNED(PCPU_BITMAP_BLOCK_SIZE, PAGE_SIZE) || + IS_ALIGNED(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE))); PCPU_SETUP_BUG_ON(pcpu_verify_alloc_info(ai) < 0); /* process group information and build config tables accordingly */ @@ -1671,64 +2109,41 @@ int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai, INIT_LIST_HEAD(&pcpu_slot[i]); /* - * Initialize static chunk. If reserved_size is zero, the - * static chunk covers static area + dynamic allocation area - * in the first chunk. If reserved_size is not zero, it - * covers static area + reserved area (mostly used for module - * static percpu allocation). + * The end of the static region needs to be aligned with the + * minimum allocation size as this offsets the reserved and + * dynamic region. The first chunk ends page aligned by + * expanding the dynamic region, therefore the dynamic region + * can be shrunk to compensate while still staying above the + * configured sizes. */ - schunk = memblock_virt_alloc(pcpu_chunk_struct_size, 0); - INIT_LIST_HEAD(&schunk->list); - INIT_LIST_HEAD(&schunk->map_extend_list); - schunk->base_addr = base_addr; - schunk->map = smap; - schunk->map_alloc = ARRAY_SIZE(smap); - schunk->immutable = true; - bitmap_fill(schunk->populated, pcpu_unit_pages); - schunk->nr_populated = pcpu_unit_pages; + static_size = ALIGN(ai->static_size, PCPU_MIN_ALLOC_SIZE); + dyn_size = ai->dyn_size - (static_size - ai->static_size); - if (ai->reserved_size) { - schunk->free_size = ai->reserved_size; - pcpu_reserved_chunk = schunk; - pcpu_reserved_chunk_limit = ai->static_size + ai->reserved_size; - } else { - schunk->free_size = dyn_size; - dyn_size = 0; /* dynamic area covered */ - } - schunk->contig_hint = schunk->free_size; - - schunk->map[0] = 1; - schunk->map[1] = ai->static_size; - schunk->map_used = 1; - if (schunk->free_size) - schunk->map[++schunk->map_used] = ai->static_size + schunk->free_size; - schunk->map[schunk->map_used] |= 1; - schunk->has_reserved = true; + /* + * Initialize first chunk. + * If the reserved_size is non-zero, this initializes the reserved + * chunk. If the reserved_size is zero, the reserved chunk is NULL + * and the dynamic region is initialized here. The first chunk, + * pcpu_first_chunk, will always point to the chunk that serves + * the dynamic region. + */ + tmp_addr = (unsigned long)base_addr + static_size; + map_size = ai->reserved_size ?: dyn_size; + chunk = pcpu_alloc_first_chunk(tmp_addr, map_size); /* init dynamic chunk if necessary */ - if (dyn_size) { - dchunk = memblock_virt_alloc(pcpu_chunk_struct_size, 0); - INIT_LIST_HEAD(&dchunk->list); - INIT_LIST_HEAD(&dchunk->map_extend_list); - dchunk->base_addr = base_addr; - dchunk->map = dmap; - dchunk->map_alloc = ARRAY_SIZE(dmap); - dchunk->immutable = true; - bitmap_fill(dchunk->populated, pcpu_unit_pages); - dchunk->nr_populated = pcpu_unit_pages; - - dchunk->contig_hint = dchunk->free_size = dyn_size; - dchunk->map[0] = 1; - dchunk->map[1] = pcpu_reserved_chunk_limit; - dchunk->map[2] = (pcpu_reserved_chunk_limit + dchunk->free_size) | 1; - dchunk->map_used = 2; - dchunk->has_reserved = true; + if (ai->reserved_size) { + pcpu_reserved_chunk = chunk; + + tmp_addr = (unsigned long)base_addr + static_size + + ai->reserved_size; + map_size = dyn_size; + chunk = pcpu_alloc_first_chunk(tmp_addr, map_size); } /* link the first chunk in */ - pcpu_first_chunk = dchunk ?: schunk; - pcpu_nr_empty_pop_pages += - pcpu_count_occupied_pages(pcpu_first_chunk, 1); + pcpu_first_chunk = chunk; + pcpu_nr_empty_pop_pages = pcpu_first_chunk->nr_empty_pop_pages; pcpu_chunk_relocate(pcpu_first_chunk, -1); pcpu_stats_chunk_alloc(); @@ -1842,6 +2257,7 @@ static struct pcpu_alloc_info * __init pcpu_build_alloc_info( */ min_unit_size = max_t(size_t, size_sum, PCPU_MIN_UNIT_SIZE); + /* determine the maximum # of units that can fit in an allocation */ alloc_size = roundup(min_unit_size, atom_size); upa = alloc_size / min_unit_size; while (alloc_size % upa || (offset_in_page(alloc_size / upa))) @@ -1868,9 +2284,9 @@ static struct pcpu_alloc_info * __init pcpu_build_alloc_info( } /* - * Expand unit size until address space usage goes over 75% - * and then as much as possible without using more address - * space. + * Wasted space is caused by a ratio imbalance of upa to group_cnt. + * Expand the unit_size until we use >= 75% of the units allocated. + * Related to atom_size, which could be much larger than the unit_size. */ last_allocs = INT_MAX; for (upa = max_upa; upa; upa--) { @@ -2299,36 +2715,6 @@ void __init setup_per_cpu_areas(void) #endif /* CONFIG_SMP */ /* - * First and reserved chunks are initialized with temporary allocation - * map in initdata so that they can be used before slab is online. - * This function is called after slab is brought up and replaces those - * with properly allocated maps. - */ -void __init percpu_init_late(void) -{ - struct pcpu_chunk *target_chunks[] = - { pcpu_first_chunk, pcpu_reserved_chunk, NULL }; - struct pcpu_chunk *chunk; - unsigned long flags; - int i; - - for (i = 0; (chunk = target_chunks[i]); i++) { - int *map; - const size_t size = PERCPU_DYNAMIC_EARLY_SLOTS * sizeof(map[0]); - - BUILD_BUG_ON(size > PAGE_SIZE); - - map = pcpu_mem_zalloc(size); - BUG_ON(!map); - - spin_lock_irqsave(&pcpu_lock, flags); - memcpy(map, chunk->map, size); - chunk->map = map; - spin_unlock_irqrestore(&pcpu_lock, flags); - } -} - -/* * Percpu allocator is initialized early during boot when neither slab or * workqueue is available. Plug async management until everything is up * and running. |