| Message ID | 20230310103210.22372-7-vbabka@suse.cz (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | remove SLOB and allow kfree() with kmem_cache_alloc() | expand |
On Fri, Mar 10, 2023 at 11:32:08AM +0100, Vlastimil Babka wrote: > Remove the SLOB implementation. > > RIP SLOB allocator (2006 - 2023) > > Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Goodbye to SLOB. Acked-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> > --- > mm/slob.c | 757 ------------------------------------------------------ > 1 file changed, 757 deletions(-) > delete mode 100644 mm/slob.c > > diff --git a/mm/slob.c b/mm/slob.c > deleted file mode 100644 > index fe567fcfa3a3..000000000000 > --- a/mm/slob.c > +++ /dev/null
On Fri, Mar 10, 2023 at 11:32:08AM +0100, Vlastimil Babka wrote: > Remove the SLOB implementation. > > RIP SLOB allocator (2006 - 2023) > > Signed-off-by: Vlastimil Babka <vbabka@suse.cz> > --- > mm/slob.c | 757 ------------------------------------------------------ > 1 file changed, 757 deletions(-) > delete mode 100644 mm/slob.c > > diff --git a/mm/slob.c b/mm/slob.c > deleted file mode 100644 > index fe567fcfa3a3..000000000000 > --- a/mm/slob.c > +++ /dev/null > @@ -1,757 +0,0 @@ > -// SPDX-License-Identifier: GPL-2.0 > -/* > - * SLOB Allocator: Simple List Of Blocks > - * > - * Matt Mackall <mpm@selenic.com> 12/30/03 > - * > - * NUMA support by Paul Mundt, 2007. > - * > - * How SLOB works: > - * > - * The core of SLOB is a traditional K&R style heap allocator, with > - * support for returning aligned objects. The granularity of this > - * allocator is as little as 2 bytes, however typically most architectures > - * will require 4 bytes on 32-bit and 8 bytes on 64-bit. > - * > - * The slob heap is a set of linked list of pages from alloc_pages(), > - * and within each page, there is a singly-linked list of free blocks > - * (slob_t). The heap is grown on demand. To reduce fragmentation, > - * heap pages are segregated into three lists, with objects less than > - * 256 bytes, objects less than 1024 bytes, and all other objects. > - * > - * Allocation from heap involves first searching for a page with > - * sufficient free blocks (using a next-fit-like approach) followed by > - * a first-fit scan of the page. Deallocation inserts objects back > - * into the free list in address order, so this is effectively an > - * address-ordered first fit. > - * > - * Above this is an implementation of kmalloc/kfree. Blocks returned > - * from kmalloc are prepended with a 4-byte header with the kmalloc size. > - * If kmalloc is asked for objects of PAGE_SIZE or larger, it calls > - * alloc_pages() directly, allocating compound pages so the page order > - * does not have to be separately tracked. > - * These objects are detected in kfree() because folio_test_slab() > - * is false for them. > - * > - * SLAB is emulated on top of SLOB by simply calling constructors and > - * destructors for every SLAB allocation. Objects are returned with the > - * 4-byte alignment unless the SLAB_HWCACHE_ALIGN flag is set, in which > - * case the low-level allocator will fragment blocks to create the proper > - * alignment. Again, objects of page-size or greater are allocated by > - * calling alloc_pages(). As SLAB objects know their size, no separate > - * size bookkeeping is necessary and there is essentially no allocation > - * space overhead, and compound pages aren't needed for multi-page > - * allocations. > - * > - * NUMA support in SLOB is fairly simplistic, pushing most of the real > - * logic down to the page allocator, and simply doing the node accounting > - * on the upper levels. In the event that a node id is explicitly > - * provided, __alloc_pages_node() with the specified node id is used > - * instead. The common case (or when the node id isn't explicitly provided) > - * will default to the current node, as per numa_node_id(). > - * > - * Node aware pages are still inserted in to the global freelist, and > - * these are scanned for by matching against the node id encoded in the > - * page flags. As a result, block allocations that can be satisfied from > - * the freelist will only be done so on pages residing on the same node, > - * in order to prevent random node placement. > - */ > - > -#include <linux/kernel.h> > -#include <linux/slab.h> > - > -#include <linux/mm.h> > -#include <linux/swap.h> /* struct reclaim_state */ > -#include <linux/cache.h> > -#include <linux/init.h> > -#include <linux/export.h> > -#include <linux/rcupdate.h> > -#include <linux/list.h> > -#include <linux/kmemleak.h> > - > -#include <trace/events/kmem.h> > - > -#include <linux/atomic.h> > - > -#include "slab.h" > -/* > - * slob_block has a field 'units', which indicates size of block if +ve, > - * or offset of next block if -ve (in SLOB_UNITs). > - * > - * Free blocks of size 1 unit simply contain the offset of the next block. > - * Those with larger size contain their size in the first SLOB_UNIT of > - * memory, and the offset of the next free block in the second SLOB_UNIT. > - */ > -#if PAGE_SIZE <= (32767 * 2) > -typedef s16 slobidx_t; > -#else > -typedef s32 slobidx_t; > -#endif > - > -struct slob_block { > - slobidx_t units; > -}; > -typedef struct slob_block slob_t; > - > -/* > - * All partially free slob pages go on these lists. > - */ > -#define SLOB_BREAK1 256 > -#define SLOB_BREAK2 1024 > -static LIST_HEAD(free_slob_small); > -static LIST_HEAD(free_slob_medium); > -static LIST_HEAD(free_slob_large); > - > -/* > - * slob_page_free: true for pages on free_slob_pages list. > - */ > -static inline int slob_page_free(struct slab *slab) > -{ > - return PageSlobFree(slab_page(slab)); > -} > - > -static void set_slob_page_free(struct slab *slab, struct list_head *list) > -{ > - list_add(&slab->slab_list, list); > - __SetPageSlobFree(slab_page(slab)); > -} > - > -static inline void clear_slob_page_free(struct slab *slab) > -{ > - list_del(&slab->slab_list); > - __ClearPageSlobFree(slab_page(slab)); > -} > - > -#define SLOB_UNIT sizeof(slob_t) > -#define SLOB_UNITS(size) DIV_ROUND_UP(size, SLOB_UNIT) > - > -/* > - * struct slob_rcu is inserted at the tail of allocated slob blocks, which > - * were created with a SLAB_TYPESAFE_BY_RCU slab. slob_rcu is used to free > - * the block using call_rcu. > - */ > -struct slob_rcu { > - struct rcu_head head; > - int size; > -}; > - > -/* > - * slob_lock protects all slob allocator structures. > - */ > -static DEFINE_SPINLOCK(slob_lock); > - > -/* > - * Encode the given size and next info into a free slob block s. > - */ > -static void set_slob(slob_t *s, slobidx_t size, slob_t *next) > -{ > - slob_t *base = (slob_t *)((unsigned long)s & PAGE_MASK); > - slobidx_t offset = next - base; > - > - if (size > 1) { > - s[0].units = size; > - s[1].units = offset; > - } else > - s[0].units = -offset; > -} > - > -/* > - * Return the size of a slob block. > - */ > -static slobidx_t slob_units(slob_t *s) > -{ > - if (s->units > 0) > - return s->units; > - return 1; > -} > - > -/* > - * Return the next free slob block pointer after this one. > - */ > -static slob_t *slob_next(slob_t *s) > -{ > - slob_t *base = (slob_t *)((unsigned long)s & PAGE_MASK); > - slobidx_t next; > - > - if (s[0].units < 0) > - next = -s[0].units; > - else > - next = s[1].units; > - return base+next; > -} > - > -/* > - * Returns true if s is the last free block in its page. > - */ > -static int slob_last(slob_t *s) > -{ > - return !((unsigned long)slob_next(s) & ~PAGE_MASK); > -} > - > -static void *slob_new_pages(gfp_t gfp, int order, int node) > -{ > - struct page *page; > - > -#ifdef CONFIG_NUMA > - if (node != NUMA_NO_NODE) > - page = __alloc_pages_node(node, gfp, order); > - else > -#endif > - page = alloc_pages(gfp, order); > - > - if (!page) > - return NULL; > - > - mod_node_page_state(page_pgdat(page), NR_SLAB_UNRECLAIMABLE_B, > - PAGE_SIZE << order); > - return page_address(page); > -} > - > -static void slob_free_pages(void *b, int order) > -{ > - struct page *sp = virt_to_page(b); > - > - if (current->reclaim_state) > - current->reclaim_state->reclaimed_slab += 1 << order; > - > - mod_node_page_state(page_pgdat(sp), NR_SLAB_UNRECLAIMABLE_B, > - -(PAGE_SIZE << order)); > - __free_pages(sp, order); > -} > - > -/* > - * slob_page_alloc() - Allocate a slob block within a given slob_page sp. > - * @sp: Page to look in. > - * @size: Size of the allocation. > - * @align: Allocation alignment. > - * @align_offset: Offset in the allocated block that will be aligned. > - * @page_removed_from_list: Return parameter. > - * > - * Tries to find a chunk of memory at least @size bytes big within @page. > - * > - * Return: Pointer to memory if allocated, %NULL otherwise. If the > - * allocation fills up @page then the page is removed from the > - * freelist, in this case @page_removed_from_list will be set to > - * true (set to false otherwise). > - */ > -static void *slob_page_alloc(struct slab *sp, size_t size, int align, > - int align_offset, bool *page_removed_from_list) > -{ > - slob_t *prev, *cur, *aligned = NULL; > - int delta = 0, units = SLOB_UNITS(size); > - > - *page_removed_from_list = false; > - for (prev = NULL, cur = sp->freelist; ; prev = cur, cur = slob_next(cur)) { > - slobidx_t avail = slob_units(cur); > - > - /* > - * 'aligned' will hold the address of the slob block so that the > - * address 'aligned'+'align_offset' is aligned according to the > - * 'align' parameter. This is for kmalloc() which prepends the > - * allocated block with its size, so that the block itself is > - * aligned when needed. > - */ > - if (align) { > - aligned = (slob_t *) > - (ALIGN((unsigned long)cur + align_offset, align) > - - align_offset); > - delta = aligned - cur; > - } > - if (avail >= units + delta) { /* room enough? */ > - slob_t *next; > - > - if (delta) { /* need to fragment head to align? */ > - next = slob_next(cur); > - set_slob(aligned, avail - delta, next); > - set_slob(cur, delta, aligned); > - prev = cur; > - cur = aligned; > - avail = slob_units(cur); > - } > - > - next = slob_next(cur); > - if (avail == units) { /* exact fit? unlink. */ > - if (prev) > - set_slob(prev, slob_units(prev), next); > - else > - sp->freelist = next; > - } else { /* fragment */ > - if (prev) > - set_slob(prev, slob_units(prev), cur + units); > - else > - sp->freelist = cur + units; > - set_slob(cur + units, avail - units, next); > - } > - > - sp->units -= units; > - if (!sp->units) { > - clear_slob_page_free(sp); > - *page_removed_from_list = true; > - } > - return cur; > - } > - if (slob_last(cur)) > - return NULL; > - } > -} > - > -/* > - * slob_alloc: entry point into the slob allocator. > - */ > -static void *slob_alloc(size_t size, gfp_t gfp, int align, int node, > - int align_offset) > -{ > - struct folio *folio; > - struct slab *sp; > - struct list_head *slob_list; > - slob_t *b = NULL; > - unsigned long flags; > - bool _unused; > - > - if (size < SLOB_BREAK1) > - slob_list = &free_slob_small; > - else if (size < SLOB_BREAK2) > - slob_list = &free_slob_medium; > - else > - slob_list = &free_slob_large; > - > - spin_lock_irqsave(&slob_lock, flags); > - /* Iterate through each partially free page, try to find room */ > - list_for_each_entry(sp, slob_list, slab_list) { > - bool page_removed_from_list = false; > -#ifdef CONFIG_NUMA > - /* > - * If there's a node specification, search for a partial > - * page with a matching node id in the freelist. > - */ > - if (node != NUMA_NO_NODE && slab_nid(sp) != node) > - continue; > -#endif > - /* Enough room on this page? */ > - if (sp->units < SLOB_UNITS(size)) > - continue; > - > - b = slob_page_alloc(sp, size, align, align_offset, &page_removed_from_list); > - if (!b) > - continue; > - > - /* > - * If slob_page_alloc() removed sp from the list then we > - * cannot call list functions on sp. If so allocation > - * did not fragment the page anyway so optimisation is > - * unnecessary. > - */ > - if (!page_removed_from_list) { > - /* > - * Improve fragment distribution and reduce our average > - * search time by starting our next search here. (see > - * Knuth vol 1, sec 2.5, pg 449) > - */ > - if (!list_is_first(&sp->slab_list, slob_list)) > - list_rotate_to_front(&sp->slab_list, slob_list); > - } > - break; > - } > - spin_unlock_irqrestore(&slob_lock, flags); > - > - /* Not enough space: must allocate a new page */ > - if (!b) { > - b = slob_new_pages(gfp & ~__GFP_ZERO, 0, node); > - if (!b) > - return NULL; > - folio = virt_to_folio(b); > - __folio_set_slab(folio); > - sp = folio_slab(folio); > - > - spin_lock_irqsave(&slob_lock, flags); > - sp->units = SLOB_UNITS(PAGE_SIZE); > - sp->freelist = b; > - INIT_LIST_HEAD(&sp->slab_list); > - set_slob(b, SLOB_UNITS(PAGE_SIZE), b + SLOB_UNITS(PAGE_SIZE)); > - set_slob_page_free(sp, slob_list); > - b = slob_page_alloc(sp, size, align, align_offset, &_unused); > - BUG_ON(!b); > - spin_unlock_irqrestore(&slob_lock, flags); > - } > - if (unlikely(gfp & __GFP_ZERO)) > - memset(b, 0, size); > - return b; > -} > - > -/* > - * slob_free: entry point into the slob allocator. > - */ > -static void slob_free(void *block, int size) > -{ > - struct slab *sp; > - slob_t *prev, *next, *b = (slob_t *)block; > - slobidx_t units; > - unsigned long flags; > - struct list_head *slob_list; > - > - if (unlikely(ZERO_OR_NULL_PTR(block))) > - return; > - BUG_ON(!size); > - > - sp = virt_to_slab(block); > - units = SLOB_UNITS(size); > - > - spin_lock_irqsave(&slob_lock, flags); > - > - if (sp->units + units == SLOB_UNITS(PAGE_SIZE)) { > - /* Go directly to page allocator. Do not pass slob allocator */ > - if (slob_page_free(sp)) > - clear_slob_page_free(sp); > - spin_unlock_irqrestore(&slob_lock, flags); > - __folio_clear_slab(slab_folio(sp)); > - slob_free_pages(b, 0); > - return; > - } > - > - if (!slob_page_free(sp)) { > - /* This slob page is about to become partially free. Easy! */ > - sp->units = units; > - sp->freelist = b; > - set_slob(b, units, > - (void *)((unsigned long)(b + > - SLOB_UNITS(PAGE_SIZE)) & PAGE_MASK)); > - if (size < SLOB_BREAK1) > - slob_list = &free_slob_small; > - else if (size < SLOB_BREAK2) > - slob_list = &free_slob_medium; > - else > - slob_list = &free_slob_large; > - set_slob_page_free(sp, slob_list); > - goto out; > - } > - > - /* > - * Otherwise the page is already partially free, so find reinsertion > - * point. > - */ > - sp->units += units; > - > - if (b < (slob_t *)sp->freelist) { > - if (b + units == sp->freelist) { > - units += slob_units(sp->freelist); > - sp->freelist = slob_next(sp->freelist); > - } > - set_slob(b, units, sp->freelist); > - sp->freelist = b; > - } else { > - prev = sp->freelist; > - next = slob_next(prev); > - while (b > next) { > - prev = next; > - next = slob_next(prev); > - } > - > - if (!slob_last(prev) && b + units == next) { > - units += slob_units(next); > - set_slob(b, units, slob_next(next)); > - } else > - set_slob(b, units, next); > - > - if (prev + slob_units(prev) == b) { > - units = slob_units(b) + slob_units(prev); > - set_slob(prev, units, slob_next(b)); > - } else > - set_slob(prev, slob_units(prev), b); > - } > -out: > - spin_unlock_irqrestore(&slob_lock, flags); > -} > - > -#ifdef CONFIG_PRINTK > -void __kmem_obj_info(struct kmem_obj_info *kpp, void *object, struct slab *slab) > -{ > - kpp->kp_ptr = object; > - kpp->kp_slab = slab; > -} > -#endif > - > -/* > - * End of slob allocator proper. Begin kmem_cache_alloc and kmalloc frontend. > - */ > - > -static __always_inline void * > -__do_kmalloc_node(size_t size, gfp_t gfp, int node, unsigned long caller) > -{ > - unsigned int *m; > - unsigned int minalign; > - void *ret; > - > - minalign = max_t(unsigned int, ARCH_KMALLOC_MINALIGN, > - arch_slab_minalign()); > - gfp &= gfp_allowed_mask; > - > - might_alloc(gfp); > - > - if (size < PAGE_SIZE - minalign) { > - int align = minalign; > - > - /* > - * For power of two sizes, guarantee natural alignment for > - * kmalloc()'d objects. > - */ > - if (is_power_of_2(size)) > - align = max_t(unsigned int, minalign, size); > - > - if (!size) > - return ZERO_SIZE_PTR; > - > - m = slob_alloc(size + minalign, gfp, align, node, minalign); > - > - if (!m) > - return NULL; > - *m = size; > - ret = (void *)m + minalign; > - > - trace_kmalloc(caller, ret, size, size + minalign, gfp, node); > - } else { > - unsigned int order = get_order(size); > - > - if (likely(order)) > - gfp |= __GFP_COMP; > - ret = slob_new_pages(gfp, order, node); > - > - trace_kmalloc(caller, ret, size, PAGE_SIZE << order, gfp, node); > - } > - > - kmemleak_alloc(ret, size, 1, gfp); > - return ret; > -} > - > -void *__kmalloc(size_t size, gfp_t gfp) > -{ > - return __do_kmalloc_node(size, gfp, NUMA_NO_NODE, _RET_IP_); > -} > -EXPORT_SYMBOL(__kmalloc); > - > -void *__kmalloc_node_track_caller(size_t size, gfp_t gfp, > - int node, unsigned long caller) > -{ > - return __do_kmalloc_node(size, gfp, node, caller); > -} > -EXPORT_SYMBOL(__kmalloc_node_track_caller); > - > -void kfree(const void *block) > -{ > - struct folio *sp; > - > - trace_kfree(_RET_IP_, block); > - > - if (unlikely(ZERO_OR_NULL_PTR(block))) > - return; > - kmemleak_free(block); > - > - sp = virt_to_folio(block); > - if (folio_test_slab(sp)) { > - unsigned int align = max_t(unsigned int, > - ARCH_KMALLOC_MINALIGN, > - arch_slab_minalign()); > - unsigned int *m = (unsigned int *)(block - align); > - > - slob_free(m, *m + align); > - } else { > - unsigned int order = folio_order(sp); > - > - mod_node_page_state(folio_pgdat(sp), NR_SLAB_UNRECLAIMABLE_B, > - -(PAGE_SIZE << order)); > - __free_pages(folio_page(sp, 0), order); > - > - } > -} > -EXPORT_SYMBOL(kfree); > - > -size_t kmalloc_size_roundup(size_t size) > -{ > - /* Short-circuit the 0 size case. */ > - if (unlikely(size == 0)) > - return 0; > - /* Short-circuit saturated "too-large" case. */ > - if (unlikely(size == SIZE_MAX)) > - return SIZE_MAX; > - > - return ALIGN(size, ARCH_KMALLOC_MINALIGN); > -} > - > -EXPORT_SYMBOL(kmalloc_size_roundup); > - > -/* can't use ksize for kmem_cache_alloc memory, only kmalloc */ > -size_t __ksize(const void *block) > -{ > - struct folio *folio; > - unsigned int align; > - unsigned int *m; > - > - BUG_ON(!block); > - if (unlikely(block == ZERO_SIZE_PTR)) > - return 0; > - > - folio = virt_to_folio(block); > - if (unlikely(!folio_test_slab(folio))) > - return folio_size(folio); > - > - align = max_t(unsigned int, ARCH_KMALLOC_MINALIGN, > - arch_slab_minalign()); > - m = (unsigned int *)(block - align); > - return SLOB_UNITS(*m) * SLOB_UNIT; > -} > - > -int __kmem_cache_create(struct kmem_cache *c, slab_flags_t flags) > -{ > - if (flags & SLAB_TYPESAFE_BY_RCU) { > - /* leave room for rcu footer at the end of object */ > - c->size += sizeof(struct slob_rcu); > - } > - > - /* Actual size allocated */ > - c->size = SLOB_UNITS(c->size) * SLOB_UNIT; > - c->flags = flags; > - return 0; > -} > - > -static void *slob_alloc_node(struct kmem_cache *c, gfp_t flags, int node) > -{ > - void *b; > - > - flags &= gfp_allowed_mask; > - > - might_alloc(flags); > - > - if (c->size < PAGE_SIZE) { > - b = slob_alloc(c->size, flags, c->align, node, 0); > - trace_kmem_cache_alloc(_RET_IP_, b, c, flags, node); > - } else { > - b = slob_new_pages(flags, get_order(c->size), node); > - trace_kmem_cache_alloc(_RET_IP_, b, c, flags, node); > - } > - > - if (b && c->ctor) { > - WARN_ON_ONCE(flags & __GFP_ZERO); > - c->ctor(b); > - } > - > - kmemleak_alloc_recursive(b, c->size, 1, c->flags, flags); > - return b; > -} > - > -void *kmem_cache_alloc(struct kmem_cache *cachep, gfp_t flags) > -{ > - return slob_alloc_node(cachep, flags, NUMA_NO_NODE); > -} > -EXPORT_SYMBOL(kmem_cache_alloc); > - > - > -void *kmem_cache_alloc_lru(struct kmem_cache *cachep, struct list_lru *lru, gfp_t flags) > -{ > - return slob_alloc_node(cachep, flags, NUMA_NO_NODE); > -} > -EXPORT_SYMBOL(kmem_cache_alloc_lru); > - > -void *__kmalloc_node(size_t size, gfp_t gfp, int node) > -{ > - return __do_kmalloc_node(size, gfp, node, _RET_IP_); > -} > -EXPORT_SYMBOL(__kmalloc_node); > - > -void *kmem_cache_alloc_node(struct kmem_cache *cachep, gfp_t gfp, int node) > -{ > - return slob_alloc_node(cachep, gfp, node); > -} > -EXPORT_SYMBOL(kmem_cache_alloc_node); > - > -static void __kmem_cache_free(void *b, int size) > -{ > - if (size < PAGE_SIZE) > - slob_free(b, size); > - else > - slob_free_pages(b, get_order(size)); > -} > - > -static void kmem_rcu_free(struct rcu_head *head) > -{ > - struct slob_rcu *slob_rcu = (struct slob_rcu *)head; > - void *b = (void *)slob_rcu - (slob_rcu->size - sizeof(struct slob_rcu)); > - > - __kmem_cache_free(b, slob_rcu->size); > -} > - > -void kmem_cache_free(struct kmem_cache *c, void *b) > -{ > - kmemleak_free_recursive(b, c->flags); > - trace_kmem_cache_free(_RET_IP_, b, c); > - if (unlikely(c->flags & SLAB_TYPESAFE_BY_RCU)) { > - struct slob_rcu *slob_rcu; > - slob_rcu = b + (c->size - sizeof(struct slob_rcu)); > - slob_rcu->size = c->size; > - call_rcu(&slob_rcu->head, kmem_rcu_free); > - } else { > - __kmem_cache_free(b, c->size); > - } > -} > -EXPORT_SYMBOL(kmem_cache_free); > - > -void kmem_cache_free_bulk(struct kmem_cache *s, size_t nr, void **p) > -{ > - size_t i; > - > - for (i = 0; i < nr; i++) { > - if (s) > - kmem_cache_free(s, p[i]); > - else > - kfree(p[i]); > - } > -} > -EXPORT_SYMBOL(kmem_cache_free_bulk); > - > -int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t nr, > - void **p) > -{ > - size_t i; > - > - for (i = 0; i < nr; i++) { > - void *x = p[i] = kmem_cache_alloc(s, flags); > - > - if (!x) { > - kmem_cache_free_bulk(s, i, p); > - return 0; > - } > - } > - return i; > -} > -EXPORT_SYMBOL(kmem_cache_alloc_bulk); > - > -int __kmem_cache_shutdown(struct kmem_cache *c) > -{ > - /* No way to check for remaining objects */ > - return 0; > -} > - > -void __kmem_cache_release(struct kmem_cache *c) > -{ > -} > - > -int __kmem_cache_shrink(struct kmem_cache *d) > -{ > - return 0; > -} > - > -static struct kmem_cache kmem_cache_boot = { > - .name = "kmem_cache", > - .size = sizeof(struct kmem_cache), > - .flags = SLAB_PANIC, > - .align = ARCH_KMALLOC_MINALIGN, > -}; > - > -void __init kmem_cache_init(void) > -{ > - kmem_cache = &kmem_cache_boot; > - slab_state = UP; > -} > - > -void __init kmem_cache_init_late(void) > -{ > - slab_state = FULL; > -} > -- > 2.39.2 > A momentous moment, congratulations and fantastic work! Very much, Acked-by: Lorenzo Stoakes <lstoakes@gmail.com>
On Fri, Mar 10, 2023 at 11:32:08AM +0100, Vlastimil Babka wrote: > Remove the SLOB implementation. > > RIP SLOB allocator (2006 - 2023) > > Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Roman Gushchin <roman.gushchin@linux.dev> Thanks!
diff --git a/mm/slob.c b/mm/slob.c deleted file mode 100644 index fe567fcfa3a3..000000000000 --- a/mm/slob.c +++ /dev/null @@ -1,757 +0,0 @@ -// SPDX-License-Identifier: GPL-2.0 -/* - * SLOB Allocator: Simple List Of Blocks - * - * Matt Mackall <mpm@selenic.com> 12/30/03 - * - * NUMA support by Paul Mundt, 2007. - * - * How SLOB works: - * - * The core of SLOB is a traditional K&R style heap allocator, with - * support for returning aligned objects. The granularity of this - * allocator is as little as 2 bytes, however typically most architectures - * will require 4 bytes on 32-bit and 8 bytes on 64-bit. - * - * The slob heap is a set of linked list of pages from alloc_pages(), - * and within each page, there is a singly-linked list of free blocks - * (slob_t). The heap is grown on demand. To reduce fragmentation, - * heap pages are segregated into three lists, with objects less than - * 256 bytes, objects less than 1024 bytes, and all other objects. - * - * Allocation from heap involves first searching for a page with - * sufficient free blocks (using a next-fit-like approach) followed by - * a first-fit scan of the page. Deallocation inserts objects back - * into the free list in address order, so this is effectively an - * address-ordered first fit. - * - * Above this is an implementation of kmalloc/kfree. Blocks returned - * from kmalloc are prepended with a 4-byte header with the kmalloc size. - * If kmalloc is asked for objects of PAGE_SIZE or larger, it calls - * alloc_pages() directly, allocating compound pages so the page order - * does not have to be separately tracked. - * These objects are detected in kfree() because folio_test_slab() - * is false for them. - * - * SLAB is emulated on top of SLOB by simply calling constructors and - * destructors for every SLAB allocation. Objects are returned with the - * 4-byte alignment unless the SLAB_HWCACHE_ALIGN flag is set, in which - * case the low-level allocator will fragment blocks to create the proper - * alignment. Again, objects of page-size or greater are allocated by - * calling alloc_pages(). As SLAB objects know their size, no separate - * size bookkeeping is necessary and there is essentially no allocation - * space overhead, and compound pages aren't needed for multi-page - * allocations. - * - * NUMA support in SLOB is fairly simplistic, pushing most of the real - * logic down to the page allocator, and simply doing the node accounting - * on the upper levels. In the event that a node id is explicitly - * provided, __alloc_pages_node() with the specified node id is used - * instead. The common case (or when the node id isn't explicitly provided) - * will default to the current node, as per numa_node_id(). - * - * Node aware pages are still inserted in to the global freelist, and - * these are scanned for by matching against the node id encoded in the - * page flags. As a result, block allocations that can be satisfied from - * the freelist will only be done so on pages residing on the same node, - * in order to prevent random node placement. - */ - -#include <linux/kernel.h> -#include <linux/slab.h> - -#include <linux/mm.h> -#include <linux/swap.h> /* struct reclaim_state */ -#include <linux/cache.h> -#include <linux/init.h> -#include <linux/export.h> -#include <linux/rcupdate.h> -#include <linux/list.h> -#include <linux/kmemleak.h> - -#include <trace/events/kmem.h> - -#include <linux/atomic.h> - -#include "slab.h" -/* - * slob_block has a field 'units', which indicates size of block if +ve, - * or offset of next block if -ve (in SLOB_UNITs). - * - * Free blocks of size 1 unit simply contain the offset of the next block. - * Those with larger size contain their size in the first SLOB_UNIT of - * memory, and the offset of the next free block in the second SLOB_UNIT. - */ -#if PAGE_SIZE <= (32767 * 2) -typedef s16 slobidx_t; -#else -typedef s32 slobidx_t; -#endif - -struct slob_block { - slobidx_t units; -}; -typedef struct slob_block slob_t; - -/* - * All partially free slob pages go on these lists. - */ -#define SLOB_BREAK1 256 -#define SLOB_BREAK2 1024 -static LIST_HEAD(free_slob_small); -static LIST_HEAD(free_slob_medium); -static LIST_HEAD(free_slob_large); - -/* - * slob_page_free: true for pages on free_slob_pages list. - */ -static inline int slob_page_free(struct slab *slab) -{ - return PageSlobFree(slab_page(slab)); -} - -static void set_slob_page_free(struct slab *slab, struct list_head *list) -{ - list_add(&slab->slab_list, list); - __SetPageSlobFree(slab_page(slab)); -} - -static inline void clear_slob_page_free(struct slab *slab) -{ - list_del(&slab->slab_list); - __ClearPageSlobFree(slab_page(slab)); -} - -#define SLOB_UNIT sizeof(slob_t) -#define SLOB_UNITS(size) DIV_ROUND_UP(size, SLOB_UNIT) - -/* - * struct slob_rcu is inserted at the tail of allocated slob blocks, which - * were created with a SLAB_TYPESAFE_BY_RCU slab. slob_rcu is used to free - * the block using call_rcu. - */ -struct slob_rcu { - struct rcu_head head; - int size; -}; - -/* - * slob_lock protects all slob allocator structures. - */ -static DEFINE_SPINLOCK(slob_lock); - -/* - * Encode the given size and next info into a free slob block s. - */ -static void set_slob(slob_t *s, slobidx_t size, slob_t *next) -{ - slob_t *base = (slob_t *)((unsigned long)s & PAGE_MASK); - slobidx_t offset = next - base; - - if (size > 1) { - s[0].units = size; - s[1].units = offset; - } else - s[0].units = -offset; -} - -/* - * Return the size of a slob block. - */ -static slobidx_t slob_units(slob_t *s) -{ - if (s->units > 0) - return s->units; - return 1; -} - -/* - * Return the next free slob block pointer after this one. - */ -static slob_t *slob_next(slob_t *s) -{ - slob_t *base = (slob_t *)((unsigned long)s & PAGE_MASK); - slobidx_t next; - - if (s[0].units < 0) - next = -s[0].units; - else - next = s[1].units; - return base+next; -} - -/* - * Returns true if s is the last free block in its page. - */ -static int slob_last(slob_t *s) -{ - return !((unsigned long)slob_next(s) & ~PAGE_MASK); -} - -static void *slob_new_pages(gfp_t gfp, int order, int node) -{ - struct page *page; - -#ifdef CONFIG_NUMA - if (node != NUMA_NO_NODE) - page = __alloc_pages_node(node, gfp, order); - else -#endif - page = alloc_pages(gfp, order); - - if (!page) - return NULL; - - mod_node_page_state(page_pgdat(page), NR_SLAB_UNRECLAIMABLE_B, - PAGE_SIZE << order); - return page_address(page); -} - -static void slob_free_pages(void *b, int order) -{ - struct page *sp = virt_to_page(b); - - if (current->reclaim_state) - current->reclaim_state->reclaimed_slab += 1 << order; - - mod_node_page_state(page_pgdat(sp), NR_SLAB_UNRECLAIMABLE_B, - -(PAGE_SIZE << order)); - __free_pages(sp, order); -} - -/* - * slob_page_alloc() - Allocate a slob block within a given slob_page sp. - * @sp: Page to look in. - * @size: Size of the allocation. - * @align: Allocation alignment. - * @align_offset: Offset in the allocated block that will be aligned. - * @page_removed_from_list: Return parameter. - * - * Tries to find a chunk of memory at least @size bytes big within @page. - * - * Return: Pointer to memory if allocated, %NULL otherwise. If the - * allocation fills up @page then the page is removed from the - * freelist, in this case @page_removed_from_list will be set to - * true (set to false otherwise). - */ -static void *slob_page_alloc(struct slab *sp, size_t size, int align, - int align_offset, bool *page_removed_from_list) -{ - slob_t *prev, *cur, *aligned = NULL; - int delta = 0, units = SLOB_UNITS(size); - - *page_removed_from_list = false; - for (prev = NULL, cur = sp->freelist; ; prev = cur, cur = slob_next(cur)) { - slobidx_t avail = slob_units(cur); - - /* - * 'aligned' will hold the address of the slob block so that the - * address 'aligned'+'align_offset' is aligned according to the - * 'align' parameter. This is for kmalloc() which prepends the - * allocated block with its size, so that the block itself is - * aligned when needed. - */ - if (align) { - aligned = (slob_t *) - (ALIGN((unsigned long)cur + align_offset, align) - - align_offset); - delta = aligned - cur; - } - if (avail >= units + delta) { /* room enough? */ - slob_t *next; - - if (delta) { /* need to fragment head to align? */ - next = slob_next(cur); - set_slob(aligned, avail - delta, next); - set_slob(cur, delta, aligned); - prev = cur; - cur = aligned; - avail = slob_units(cur); - } - - next = slob_next(cur); - if (avail == units) { /* exact fit? unlink. */ - if (prev) - set_slob(prev, slob_units(prev), next); - else - sp->freelist = next; - } else { /* fragment */ - if (prev) - set_slob(prev, slob_units(prev), cur + units); - else - sp->freelist = cur + units; - set_slob(cur + units, avail - units, next); - } - - sp->units -= units; - if (!sp->units) { - clear_slob_page_free(sp); - *page_removed_from_list = true; - } - return cur; - } - if (slob_last(cur)) - return NULL; - } -} - -/* - * slob_alloc: entry point into the slob allocator. - */ -static void *slob_alloc(size_t size, gfp_t gfp, int align, int node, - int align_offset) -{ - struct folio *folio; - struct slab *sp; - struct list_head *slob_list; - slob_t *b = NULL; - unsigned long flags; - bool _unused; - - if (size < SLOB_BREAK1) - slob_list = &free_slob_small; - else if (size < SLOB_BREAK2) - slob_list = &free_slob_medium; - else - slob_list = &free_slob_large; - - spin_lock_irqsave(&slob_lock, flags); - /* Iterate through each partially free page, try to find room */ - list_for_each_entry(sp, slob_list, slab_list) { - bool page_removed_from_list = false; -#ifdef CONFIG_NUMA - /* - * If there's a node specification, search for a partial - * page with a matching node id in the freelist. - */ - if (node != NUMA_NO_NODE && slab_nid(sp) != node) - continue; -#endif - /* Enough room on this page? */ - if (sp->units < SLOB_UNITS(size)) - continue; - - b = slob_page_alloc(sp, size, align, align_offset, &page_removed_from_list); - if (!b) - continue; - - /* - * If slob_page_alloc() removed sp from the list then we - * cannot call list functions on sp. If so allocation - * did not fragment the page anyway so optimisation is - * unnecessary. - */ - if (!page_removed_from_list) { - /* - * Improve fragment distribution and reduce our average - * search time by starting our next search here. (see - * Knuth vol 1, sec 2.5, pg 449) - */ - if (!list_is_first(&sp->slab_list, slob_list)) - list_rotate_to_front(&sp->slab_list, slob_list); - } - break; - } - spin_unlock_irqrestore(&slob_lock, flags); - - /* Not enough space: must allocate a new page */ - if (!b) { - b = slob_new_pages(gfp & ~__GFP_ZERO, 0, node); - if (!b) - return NULL; - folio = virt_to_folio(b); - __folio_set_slab(folio); - sp = folio_slab(folio); - - spin_lock_irqsave(&slob_lock, flags); - sp->units = SLOB_UNITS(PAGE_SIZE); - sp->freelist = b; - INIT_LIST_HEAD(&sp->slab_list); - set_slob(b, SLOB_UNITS(PAGE_SIZE), b + SLOB_UNITS(PAGE_SIZE)); - set_slob_page_free(sp, slob_list); - b = slob_page_alloc(sp, size, align, align_offset, &_unused); - BUG_ON(!b); - spin_unlock_irqrestore(&slob_lock, flags); - } - if (unlikely(gfp & __GFP_ZERO)) - memset(b, 0, size); - return b; -} - -/* - * slob_free: entry point into the slob allocator. - */ -static void slob_free(void *block, int size) -{ - struct slab *sp; - slob_t *prev, *next, *b = (slob_t *)block; - slobidx_t units; - unsigned long flags; - struct list_head *slob_list; - - if (unlikely(ZERO_OR_NULL_PTR(block))) - return; - BUG_ON(!size); - - sp = virt_to_slab(block); - units = SLOB_UNITS(size); - - spin_lock_irqsave(&slob_lock, flags); - - if (sp->units + units == SLOB_UNITS(PAGE_SIZE)) { - /* Go directly to page allocator. Do not pass slob allocator */ - if (slob_page_free(sp)) - clear_slob_page_free(sp); - spin_unlock_irqrestore(&slob_lock, flags); - __folio_clear_slab(slab_folio(sp)); - slob_free_pages(b, 0); - return; - } - - if (!slob_page_free(sp)) { - /* This slob page is about to become partially free. Easy! */ - sp->units = units; - sp->freelist = b; - set_slob(b, units, - (void *)((unsigned long)(b + - SLOB_UNITS(PAGE_SIZE)) & PAGE_MASK)); - if (size < SLOB_BREAK1) - slob_list = &free_slob_small; - else if (size < SLOB_BREAK2) - slob_list = &free_slob_medium; - else - slob_list = &free_slob_large; - set_slob_page_free(sp, slob_list); - goto out; - } - - /* - * Otherwise the page is already partially free, so find reinsertion - * point. - */ - sp->units += units; - - if (b < (slob_t *)sp->freelist) { - if (b + units == sp->freelist) { - units += slob_units(sp->freelist); - sp->freelist = slob_next(sp->freelist); - } - set_slob(b, units, sp->freelist); - sp->freelist = b; - } else { - prev = sp->freelist; - next = slob_next(prev); - while (b > next) { - prev = next; - next = slob_next(prev); - } - - if (!slob_last(prev) && b + units == next) { - units += slob_units(next); - set_slob(b, units, slob_next(next)); - } else - set_slob(b, units, next); - - if (prev + slob_units(prev) == b) { - units = slob_units(b) + slob_units(prev); - set_slob(prev, units, slob_next(b)); - } else - set_slob(prev, slob_units(prev), b); - } -out: - spin_unlock_irqrestore(&slob_lock, flags); -} - -#ifdef CONFIG_PRINTK -void __kmem_obj_info(struct kmem_obj_info *kpp, void *object, struct slab *slab) -{ - kpp->kp_ptr = object; - kpp->kp_slab = slab; -} -#endif - -/* - * End of slob allocator proper. Begin kmem_cache_alloc and kmalloc frontend. - */ - -static __always_inline void * -__do_kmalloc_node(size_t size, gfp_t gfp, int node, unsigned long caller) -{ - unsigned int *m; - unsigned int minalign; - void *ret; - - minalign = max_t(unsigned int, ARCH_KMALLOC_MINALIGN, - arch_slab_minalign()); - gfp &= gfp_allowed_mask; - - might_alloc(gfp); - - if (size < PAGE_SIZE - minalign) { - int align = minalign; - - /* - * For power of two sizes, guarantee natural alignment for - * kmalloc()'d objects. - */ - if (is_power_of_2(size)) - align = max_t(unsigned int, minalign, size); - - if (!size) - return ZERO_SIZE_PTR; - - m = slob_alloc(size + minalign, gfp, align, node, minalign); - - if (!m) - return NULL; - *m = size; - ret = (void *)m + minalign; - - trace_kmalloc(caller, ret, size, size + minalign, gfp, node); - } else { - unsigned int order = get_order(size); - - if (likely(order)) - gfp |= __GFP_COMP; - ret = slob_new_pages(gfp, order, node); - - trace_kmalloc(caller, ret, size, PAGE_SIZE << order, gfp, node); - } - - kmemleak_alloc(ret, size, 1, gfp); - return ret; -} - -void *__kmalloc(size_t size, gfp_t gfp) -{ - return __do_kmalloc_node(size, gfp, NUMA_NO_NODE, _RET_IP_); -} -EXPORT_SYMBOL(__kmalloc); - -void *__kmalloc_node_track_caller(size_t size, gfp_t gfp, - int node, unsigned long caller) -{ - return __do_kmalloc_node(size, gfp, node, caller); -} -EXPORT_SYMBOL(__kmalloc_node_track_caller); - -void kfree(const void *block) -{ - struct folio *sp; - - trace_kfree(_RET_IP_, block); - - if (unlikely(ZERO_OR_NULL_PTR(block))) - return; - kmemleak_free(block); - - sp = virt_to_folio(block); - if (folio_test_slab(sp)) { - unsigned int align = max_t(unsigned int, - ARCH_KMALLOC_MINALIGN, - arch_slab_minalign()); - unsigned int *m = (unsigned int *)(block - align); - - slob_free(m, *m + align); - } else { - unsigned int order = folio_order(sp); - - mod_node_page_state(folio_pgdat(sp), NR_SLAB_UNRECLAIMABLE_B, - -(PAGE_SIZE << order)); - __free_pages(folio_page(sp, 0), order); - - } -} -EXPORT_SYMBOL(kfree); - -size_t kmalloc_size_roundup(size_t size) -{ - /* Short-circuit the 0 size case. */ - if (unlikely(size == 0)) - return 0; - /* Short-circuit saturated "too-large" case. */ - if (unlikely(size == SIZE_MAX)) - return SIZE_MAX; - - return ALIGN(size, ARCH_KMALLOC_MINALIGN); -} - -EXPORT_SYMBOL(kmalloc_size_roundup); - -/* can't use ksize for kmem_cache_alloc memory, only kmalloc */ -size_t __ksize(const void *block) -{ - struct folio *folio; - unsigned int align; - unsigned int *m; - - BUG_ON(!block); - if (unlikely(block == ZERO_SIZE_PTR)) - return 0; - - folio = virt_to_folio(block); - if (unlikely(!folio_test_slab(folio))) - return folio_size(folio); - - align = max_t(unsigned int, ARCH_KMALLOC_MINALIGN, - arch_slab_minalign()); - m = (unsigned int *)(block - align); - return SLOB_UNITS(*m) * SLOB_UNIT; -} - -int __kmem_cache_create(struct kmem_cache *c, slab_flags_t flags) -{ - if (flags & SLAB_TYPESAFE_BY_RCU) { - /* leave room for rcu footer at the end of object */ - c->size += sizeof(struct slob_rcu); - } - - /* Actual size allocated */ - c->size = SLOB_UNITS(c->size) * SLOB_UNIT; - c->flags = flags; - return 0; -} - -static void *slob_alloc_node(struct kmem_cache *c, gfp_t flags, int node) -{ - void *b; - - flags &= gfp_allowed_mask; - - might_alloc(flags); - - if (c->size < PAGE_SIZE) { - b = slob_alloc(c->size, flags, c->align, node, 0); - trace_kmem_cache_alloc(_RET_IP_, b, c, flags, node); - } else { - b = slob_new_pages(flags, get_order(c->size), node); - trace_kmem_cache_alloc(_RET_IP_, b, c, flags, node); - } - - if (b && c->ctor) { - WARN_ON_ONCE(flags & __GFP_ZERO); - c->ctor(b); - } - - kmemleak_alloc_recursive(b, c->size, 1, c->flags, flags); - return b; -} - -void *kmem_cache_alloc(struct kmem_cache *cachep, gfp_t flags) -{ - return slob_alloc_node(cachep, flags, NUMA_NO_NODE); -} -EXPORT_SYMBOL(kmem_cache_alloc); - - -void *kmem_cache_alloc_lru(struct kmem_cache *cachep, struct list_lru *lru, gfp_t flags) -{ - return slob_alloc_node(cachep, flags, NUMA_NO_NODE); -} -EXPORT_SYMBOL(kmem_cache_alloc_lru); - -void *__kmalloc_node(size_t size, gfp_t gfp, int node) -{ - return __do_kmalloc_node(size, gfp, node, _RET_IP_); -} -EXPORT_SYMBOL(__kmalloc_node); - -void *kmem_cache_alloc_node(struct kmem_cache *cachep, gfp_t gfp, int node) -{ - return slob_alloc_node(cachep, gfp, node); -} -EXPORT_SYMBOL(kmem_cache_alloc_node); - -static void __kmem_cache_free(void *b, int size) -{ - if (size < PAGE_SIZE) - slob_free(b, size); - else - slob_free_pages(b, get_order(size)); -} - -static void kmem_rcu_free(struct rcu_head *head) -{ - struct slob_rcu *slob_rcu = (struct slob_rcu *)head; - void *b = (void *)slob_rcu - (slob_rcu->size - sizeof(struct slob_rcu)); - - __kmem_cache_free(b, slob_rcu->size); -} - -void kmem_cache_free(struct kmem_cache *c, void *b) -{ - kmemleak_free_recursive(b, c->flags); - trace_kmem_cache_free(_RET_IP_, b, c); - if (unlikely(c->flags & SLAB_TYPESAFE_BY_RCU)) { - struct slob_rcu *slob_rcu; - slob_rcu = b + (c->size - sizeof(struct slob_rcu)); - slob_rcu->size = c->size; - call_rcu(&slob_rcu->head, kmem_rcu_free); - } else { - __kmem_cache_free(b, c->size); - } -} -EXPORT_SYMBOL(kmem_cache_free); - -void kmem_cache_free_bulk(struct kmem_cache *s, size_t nr, void **p) -{ - size_t i; - - for (i = 0; i < nr; i++) { - if (s) - kmem_cache_free(s, p[i]); - else - kfree(p[i]); - } -} -EXPORT_SYMBOL(kmem_cache_free_bulk); - -int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t nr, - void **p) -{ - size_t i; - - for (i = 0; i < nr; i++) { - void *x = p[i] = kmem_cache_alloc(s, flags); - - if (!x) { - kmem_cache_free_bulk(s, i, p); - return 0; - } - } - return i; -} -EXPORT_SYMBOL(kmem_cache_alloc_bulk); - -int __kmem_cache_shutdown(struct kmem_cache *c) -{ - /* No way to check for remaining objects */ - return 0; -} - -void __kmem_cache_release(struct kmem_cache *c) -{ -} - -int __kmem_cache_shrink(struct kmem_cache *d) -{ - return 0; -} - -static struct kmem_cache kmem_cache_boot = { - .name = "kmem_cache", - .size = sizeof(struct kmem_cache), - .flags = SLAB_PANIC, - .align = ARCH_KMALLOC_MINALIGN, -}; - -void __init kmem_cache_init(void) -{ - kmem_cache = &kmem_cache_boot; - slab_state = UP; -} - -void __init kmem_cache_init_late(void) -{ - slab_state = FULL; -}
Remove the SLOB implementation. RIP SLOB allocator (2006 - 2023) Signed-off-by: Vlastimil Babka <vbabka@suse.cz> --- mm/slob.c | 757 ------------------------------------------------------ 1 file changed, 757 deletions(-) delete mode 100644 mm/slob.c