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mm/slab: use kmalloc_node() for off slab freelist_idx_t array allocation

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After commit d6a71648db ("mm/slab: kmalloc: pass requests larger than
order-1 page to page allocator"), SLAB passes large ( > PAGE_SIZE * 2)
requests to buddy like SLUB does.

SLAB has been using kmalloc caches to allocate freelist_idx_t array for
off slab caches. But after the commit, freelist_size can be bigger than
KMALLOC_MAX_CACHE_SIZE.

Instead of using pointer to kmalloc cache, use kmalloc_node() and only
check if the kmalloc cache is off slab during calculate_slab_order().
If freelist_size > KMALLOC_MAX_CACHE_SIZE, no looping condition happens
as it allocates freelist_idx_t array directly from buddy.

Link: https://lore.kernel.org/all/20221014205818.GA1428667@roeck-us.net/
Reported-and-tested-by: Guenter Roeck <linux@roeck-us.net>
Fixes: d6a71648db ("mm/slab: kmalloc: pass requests larger than order-1 page to page allocator")
Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
This commit is contained in:
Hyeonggon Yoo 2022-10-15 13:34:29 +09:00 • committed by Vlastimil Babka
parent d5eff73690
commit e36ce448a0
2 changed files with 18 additions and 18 deletions
Download patch file Download diff file Expand all files Collapse all files

1
include/linux/slab_def.h
View file

@ -33,7 +33,6 @@ struct kmem_cache {
size_t colour; /* cache colouring range */ size_t colour; /* cache colouring range */
unsigned int colour_off; /* colour offset */ unsigned int colour_off; /* colour offset */
struct kmem_cache *freelist_cache;
unsigned int freelist_size; unsigned int freelist_size;
/* constructor func */ /* constructor func */

35
mm/slab.c
View file

@ -1619,7 +1619,7 @@ static void slab_destroy(struct kmem_cache *cachep, struct slab *slab)
* although actual page can be freed in rcu context * although actual page can be freed in rcu context
*/ */
if (OFF_SLAB(cachep)) if (OFF_SLAB(cachep))
kmem_cache_free(cachep->freelist_cache, freelist); kfree(freelist);
} }
/* /*
@ -1671,21 +1671,27 @@ static size_t calculate_slab_order(struct kmem_cache *cachep,
if (flags & CFLGS_OFF_SLAB) { if (flags & CFLGS_OFF_SLAB) {
struct kmem_cache *freelist_cache; struct kmem_cache *freelist_cache;
size_t freelist_size; size_t freelist_size;
size_t freelist_cache_size;
freelist_size = num * sizeof(freelist_idx_t); freelist_size = num * sizeof(freelist_idx_t);
freelist_cache = kmalloc_slab(freelist_size, 0u); if (freelist_size > KMALLOC_MAX_CACHE_SIZE) {
if (!freelist_cache) freelist_cache_size = PAGE_SIZE << get_order(freelist_size);
continue; } else {
freelist_cache = kmalloc_slab(freelist_size, 0u);
if (!freelist_cache)
continue;
freelist_cache_size = freelist_cache->size;
/* /*
* Needed to avoid possible looping condition * Needed to avoid possible looping condition
* in cache_grow_begin() * in cache_grow_begin()
*/ */
if (OFF_SLAB(freelist_cache)) if (OFF_SLAB(freelist_cache))
continue; continue;
}
/* check if off slab has enough benefit */ /* check if off slab has enough benefit */
if (freelist_cache->size > cachep->size / 2) if (freelist_cache_size > cachep->size / 2)
continue; continue;
} }
@ -2061,11 +2067,6 @@ done:
cachep->flags &= ~(SLAB_RED_ZONE | SLAB_STORE_USER); cachep->flags &= ~(SLAB_RED_ZONE | SLAB_STORE_USER);
#endif #endif
if (OFF_SLAB(cachep)) {
cachep->freelist_cache =
kmalloc_slab(cachep->freelist_size, 0u);
}
err = setup_cpu_cache(cachep, gfp); err = setup_cpu_cache(cachep, gfp);
if (err) { if (err) {
__kmem_cache_release(cachep); __kmem_cache_release(cachep);
@ -2292,7 +2293,7 @@ static void *alloc_slabmgmt(struct kmem_cache *cachep,
freelist = NULL; freelist = NULL;
else if (OFF_SLAB(cachep)) { else if (OFF_SLAB(cachep)) {
/* Slab management obj is off-slab. */ /* Slab management obj is off-slab. */
freelist = kmem_cache_alloc_node(cachep->freelist_cache, freelist = kmalloc_node(cachep->freelist_size,
local_flags, nodeid); local_flags, nodeid);
} else { } else {
/* We will use last bytes at the slab for freelist */ /* We will use last bytes at the slab for freelist */