Re: [PATCH] fs: use kmalloc() to allocate fdmem if possible

Eric Dumazet
2010-05-04T05:33:09Z

Le mardi 04 mai 2010 à 12:20 +0800, Changli Gao a écrit :

> we can use alloc_pages_exact()/free_pages_exact() when size is larger
> than PAGE_SIZE, then size isn't needed to be a power of two.
>
> void *kvmalloc(size_t size)
> {
> void *ptr;
>
> if (size < PAGE_SIZE)
> return kmalloc(size, GFP_KERNEL);
> ptr = alloc_pages_exact(size, GFP_KERNEL | __GFP_NOWARN);
> if (ptr)
> return ptr;
> return vmalloc(size);
> }
>
> void *kvfree(void *ptr, size_t size)
> {
> BUG_ON(in_interrupt());
> if (size < PAGE_SIZE)
> kfree(ptr);
> else if (is_vmalloc_addr(ptr))
> vfree(ptr);
> else
> free_pages_exact(ptr, size);
> }

Yes, this has the drawback to need 'size' in kvfree(), but it should not
be a problem for users of this code.

alloc_pages_exact() also fragments high order page, but I guess it's not
worse than kmalloc() in this context.