On Mon, Jan 23, 2023 at 03:11:20PM +0500, Muhammad Usama Anjum wrote:
One thing worth mention is, I think for async wp it doesn't need to be restricted by UFFD_USER_MODE_ONLY, because comparing to the sync messages it has no risk of being utilized for malicious purposes.
I think with updated handling path updated in do_wp_page() and wp_huge_pmd() in version, UFFD_USER_MODE_ONLY will not affect us.
This is more or less a comment for the design, the new code should work (by bypassing handle_userfaultfd(), where this bit was checked).
We'll need an man page update if this feature will be merged [1], and if so it'll need to be updated for the UFFD_USER_MODE_ONLY section regarding to async uffd-wp support too. I think that can also be worked out after the series being accepted first, so just a heads up.
[1] https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git