Re: [PATCH][RESEND] Allocate userspace memory for older userspace (v2)

[Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>]

dAnthony Liguori wrote:
> Allocate a userspace buffer for older userspaces.  Also eliminate phys_mem
> buffer.  The memset() in kvmctl really kills initial memory usage but swapping
> does even with old userspaces.
>
> Since v1, fixed a bug in slot creation.
>
> I send the previous patch in response to a mail instead of top level so I'm
> resending properly.
>
>   


This is really nice, especially the diffstat.

> Signed-off-by: Anthony Liguori <aliguori-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
> @@ -745,29 +727,27 @@ static int kvm_vm_ioctl_set_memory_region(struct kvm *kvm,
>  	r = -ENOMEM;
>  
>  	/* Allocate if a slot is being created */
> -	if (npages && !new.phys_mem) {
> -		new.phys_mem = vmalloc(npages * sizeof(struct page *));
> -
> -		if (!new.phys_mem)
> -			goto out_unlock;
> -
> +	if (npages && !new.rmap) {
>  		new.rmap = vmalloc(npages * sizeof(struct page *));
>  
>  		if (!new.rmap)
>  			goto out_unlock;
>  
> -		memset(new.phys_mem, 0, npages * sizeof(struct page *));
>  		memset(new.rmap, 0, npages * sizeof(*new.rmap));
> -		if (user_alloc) {
> -			new.user_alloc = 1;
> +
> +		if (user_alloc)
>  			new.userspace_addr = mem->userspace_addr;
> -		} else {
> -			for (i = 0; i < npages; ++i) {
> -				new.phys_mem[i] = alloc_page(GFP_HIGHUSER
> -							     | __GFP_ZERO);
> -				if (!new.phys_mem[i])
> -					goto out_unlock;
> -			}
> +		else {
> +			down_write(&current->mm->mmap_sem);
> +			new.userspace_addr = do_mmap(NULL, 0,
> +						     npages * PAGE_SIZE,
> +						     PROT_READ | PROT_WRITE,
> +						     MAP_SHARED | MAP_ANONYMOUS,
> +						     0);
> +			up_write(&current->mm->mmap_sem);
> +
> +			if (new.userspace_addr > -1024UL)
>   

Surely there's some macro to test for this type of error return?  Also 
we may want to return the do_mmap() error code here (not sure).

> +				goto out_unlock;
>  		}
>  	}
>   


-- 
error compiling committee.c: too many arguments to function


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