Re: [PATCH 1/9] mm: turn migrate_vma upside down

[Christoph Hellwig]

On Tue, Jul 30, 2019 at 06:46:25PM -0700, Ralph Campbell wrote:
>>   	for (i = 0; i < npages; i += c) {
>> -		unsigned long next;
>> -
>>   		c = min(SG_MAX_SINGLE_ALLOC, npages);
>> -		next = start + (c << PAGE_SHIFT);
>> -		ret = migrate_vma(&nouveau_dmem_migrate_ops, vma, start,
>> -				  next, src_pfns, dst_pfns, &migrate);
>> +		args.end = start + (c << PAGE_SHIFT);
>
> Since migrate_vma_setup() is called in a loop, either args.cpages and
> args.npages need to be cleared here or cleared in migrate_vma_setup().

I think clearing everything that is not used for argument passing in
migrate_vma_setup is a good idea.  I'll do that.

Btw, it seems like this was a fullquote just for the little comment
as far as I could tell from wading through it.  It would be very
appreciated to properly quote the replies.