On Fri, Mar 08, 2019 at 02:31:58PM +0000, Bernard Metzler wrote:
> >> + for (i = 0; num_pages; i++) {
> >> + int got, nents = min_t(int, num_pages, PAGES_PER_CHUNK);
> >> +
> >> + umem->page_chunk[i].p = kcalloc(nents, sizeof(struct page *),
> >> + GFP_KERNEL);
> >> + if (!umem->page_chunk[i].p) {
> >> + rv = -ENOMEM;
> >> + goto out;
> >> + }
> >> + got = 0;
> >> + while (nents) {
> >> + struct page **plist = &umem->page_chunk[i].p[got];
> >> +
> >> + rv = get_user_pages(first_page_va, nents, FOLL_WRITE,
> >> + plist, NULL);
> >> + if (rv < 0)
> >> + goto out;
> >> +
> >> + umem->num_pages += rv;
> >> + atomic64_add(rv, ¤t->mm->pinned_vm);
> >> + first_page_va += rv * PAGE_SIZE;
> >> + nents -= rv;
> >> + got += rv;
> >> + }
> >> + num_pages -= got;
> >> + }
> >
> >Actually why isn't this just using umem_get?
>
>
> I found it not really optimized for a fast lookup of a page from a
> vaddr. I had all that umem in before, and it was a mess if one
> wants to start sending/receiving from/to an address or resume to
> do so w/o searching through the sg lists again.
> I am not sure it is as efficient in rxe (didn't check).
> siw_get_upage() is rather simple in the end and does what I need.
You are still better to use umem_get and then transform the sgl into
something you want.
I don't like seeing drivers mess with mm's and things like this, they
usually get it wrong.
Jason
