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

Changli Gao
2010-05-04T04:21:09Z

On Mon, May 3, 2010 at 5:13 PM, Eric Dumazet <eric.dumazet@gmail.com> wrote:
>
> /*
>  * Warning: if size is not a power of two, kmalloc() might
>  * waste memory because of its requirements.
>  */
> void *kvmalloc(size_t size)
> {
>        void *ptr = kmalloc(size, GFP_KERNEL | __GFP_NOWARN);
>
>        if (ptr)
>                return ptr;
>        return vmalloc(size);
> }

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);
}

>
> void kvfree(void *ptr)
> {
>        BUG_ON(in_interrupt());
>        if (is_vmalloc_addr(ptr))
>                vfree(ptr);
>        else
>                kfree(ptr);
> }
>