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SubjectRe: [PATCH] SLOB allocator imcompatible SLAB
On Fri, Jun 22, 2007 at 05:08:07PM +0900, Yoshinori Sato wrote:
> Because the page which SLOB allocator got does not have PG_slab,

This is for a NOMMU system?

You're using an old kernel with an old version of SLOB. SLOB in newer
kernels actually sets per-page flags. Nick, can you see any reason not
to s/PG_active/PG_slab/ in the current code?

> Signed-off-by: Yoshinori Sato <ysato@users.sourceforge.jp>
>
> diff --git a/mm/slob.c b/mm/slob.c
> index 71976c5..d10bcda 100644
> --- a/mm/slob.c
> +++ b/mm/slob.c
> @@ -73,6 +73,21 @@ static DEFINE_SPINLOCK(block_lock);
> static void slob_free(void *b, int size);
> static void slob_timer_cbk(void);
>
> +static inline void set_slabflags(const void *ptr, int order)
> +{
> + int i;
> + struct page *page = virt_to_page(ptr);
> + for (i = 0; i < (1 << order); i++)
> + __SetPageSlab(page++);
> +}
> +
> +static inline void clear_slabflags(const void *ptr, int order)
> +{
> + int i;
> + struct page *page = virt_to_page(ptr);
> + for (i = 0; i < (1 << order); i++)
> + __ClearPageSlab(page++);
> +}
>
> static void *slob_alloc(size_t size, gfp_t gfp, int align)
> {
> @@ -180,6 +195,7 @@ void *__kmalloc(size_t size, gfp_t gfp)
> bb->pages = (void *)__get_free_pages(gfp, bb->order);
>
> if (bb->pages) {
> + set_slabflags(bb->pages, bb->order);
> spin_lock_irqsave(&block_lock, flags);
> bb->next = bigblocks;
> bigblocks = bb;
> @@ -240,6 +256,7 @@ void kfree(const void *block)
> if (bb->pages == block) {
> *last = bb->next;
> spin_unlock_irqrestore(&block_lock, flags);
> + clear_slabflags(block, bb->order);
> free_pages((unsigned long)block, bb->order);
> slob_free(bb, sizeof(bigblock_t));
> return;
> @@ -323,9 +340,11 @@ void *kmem_cache_alloc(struct kmem_cache *c, gfp_t flags)
>
> if (c->size < PAGE_SIZE)
> b = slob_alloc(c->size, flags, c->align);
> - else
> + else {
> b = (void *)__get_free_pages(flags, get_order(c->size));
> -
> + if (b)
> + set_slabflags(b, get_order(c->size));
> + }
> if (c->ctor)
> c->ctor(b, c, 0);
>
> @@ -347,8 +366,10 @@ static void __kmem_cache_free(void *b, int size)
> {
> if (size < PAGE_SIZE)
> slob_free(b, size);
> - else
> + else {
> + clear_slabflags(b, get_order(size));
> free_pages((unsigned long)b, get_order(size));
> + }
> }
>
> static void kmem_rcu_free(struct rcu_head *head)

--
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