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mm/slub: Convert detached_freelist to use a struct slab 

This gives us a little bit of extra typesafety as we know that nobody
called virt_to_page() instead of virt_to_head_page().

[ vbabka@suse.cz: Use folio as intermediate step when filtering out
  large kmalloc pages ]

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Roman Gushchin <guro@fb.com>
This commit is contained in:
Matthew Wilcox (Oracle) 2021-10-04 14:45:58 +01:00 committed by Vlastimil Babka
parent 0b3eb091d5
commit cc465c3b23
1 changed files with 17 additions and 14 deletions
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31
mm/slub.c
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@ -3532,7 +3532,7 @@ void kmem_cache_free(struct kmem_cache *s, void *x)
EXPORT_SYMBOL(kmem_cache_free);
struct detached_freelist {
struct page *page;
struct slab *slab;
void *tail;
void *freelist;
int cnt;
@ -3554,8 +3554,8 @@ static inline void free_nonslab_page(struct page *page, void *object)
/*
* This function progressively scans the array with free objects (with
* a limited look ahead) and extract objects belonging to the same
* page. It builds a detached freelist directly within the given
* page/objects. This can happen without any need for
* slab. It builds a detached freelist directly within the given
* slab/objects. This can happen without any need for
* synchronization, because the objects are owned by running process.
* The freelist is build up as a single linked list in the objects.
* The idea is, that this detached freelist can then be bulk
@ -3570,10 +3570,11 @@ int build_detached_freelist(struct kmem_cache *s, size_t size,
size_t first_skipped_index = 0;
int lookahead = 3;
void *object;
struct page *page;
struct folio *folio;
struct slab *slab;
/* Always re-init detached_freelist */
df->page = NULL;
df->slab = NULL;
do {
object = p[--size];
@ -3583,17 +3584,19 @@ int build_detached_freelist(struct kmem_cache *s, size_t size,
if (!object)
return 0;
page = virt_to_head_page(object);
folio = virt_to_folio(object);
if (!s) {
/* Handle kalloc'ed objects */
if (unlikely(!PageSlab(page))) {
free_nonslab_page(page, object);
if (unlikely(!folio_test_slab(folio))) {
free_nonslab_page(folio_page(folio, 0), object);
p[size] = NULL; /* mark object processed */
return size;
}
/* Derive kmem_cache from object */
df->s = page->slab_cache;
slab = folio_slab(folio);
df->s = slab->slab_cache;
} else {
slab = folio_slab(folio);
df->s = cache_from_obj(s, object); /* Support for memcg */
}
@ -3605,7 +3608,7 @@ int build_detached_freelist(struct kmem_cache *s, size_t size,
}
/* Start new detached freelist */
df->page = page;
df->slab = slab;
set_freepointer(df->s, object, NULL);
df->tail = object;
df->freelist = object;
@ -3617,8 +3620,8 @@ int build_detached_freelist(struct kmem_cache *s, size_t size,
if (!object)
continue; /* Skip processed objects */
/* df->page is always set at this point */
if (df->page == virt_to_head_page(object)) {
/* df->slab is always set at this point */
if (df->slab == virt_to_slab(object)) {
/* Opportunity build freelist */
set_freepointer(df->s, object, df->freelist);
df->freelist = object;
@ -3650,10 +3653,10 @@ void kmem_cache_free_bulk(struct kmem_cache *s, size_t size, void **p)
struct detached_freelist df;
size = build_detached_freelist(s, size, p, &df);
if (!df.page)
if (!df.slab)
continue;
slab_free(df.s, df.page, df.freelist, df.tail, df.cnt, _RET_IP_);
slab_free(df.s, slab_page(df.slab), df.freelist, df.tail, df.cnt, _RET_IP_);
} while (likely(size));
}
EXPORT_SYMBOL(kmem_cache_free_bulk);