[lustre-devel] [PATCH v3 0/2] iov_iter: allow iov_iter_get_pages_alloc to allocate more pages per call

Linus Torvalds torvalds at linux-foundation.org
Fri Feb 3 10:29:23 PST 2017

On Thu, Feb 2, 2017 at 11:29 PM, Al Viro <viro at zeniv.linux.org.uk> wrote:
> get_user_pages() relies upon find_extend_vma() to reject kernel
> addresses; the fast side of get_user_pages_fast() doesn't have anything
> of that sort

It is *supposed* to have it.

See pte_allows_gup(), for example. In particular, it requires the
_PAGE_USER bit in the PTE (and the devpte case should require

So no, get_user_pages_fast() can not look up kernel pages. If it does,
that would be a bug.


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