On Tue, Apr 19, 2022 at 04:14:11PM -0400, Johannes Weiner wrote: > Hi Peter, > > On Tue, Apr 19, 2022 at 03:59:21PM -0400, Peter Xu wrote: > > @@ -910,16 +910,16 @@ config ANON_VMA_NAME > > difference in their name. > > > > config PTE_MARKER > > - bool "Marker PTEs support" > > - default y > > + bool > > > > help > > Allows to create marker PTEs for file-backed memory. > > > > config PTE_MARKER_UFFD_WP > > - bool "Marker PTEs support for userfaultfd write protection" > > + bool "Userfaultfd write protection support for shmem/hugetlbfs" > > default y > > - depends on PTE_MARKER && HAVE_ARCH_USERFAULTFD_WP > > + depends on HAVE_ARCH_USERFAULTFD_WP > > + select PTE_MARKER > > This is much easier to understand, thanks! Cool! Sent as a formal patch just now. > > Btw, this doesn't do much without userfaultfd being enabled in > general, right? So far yes, but I'm thinking there can be potential other users of PTE_MARKERS from mm world. The most close discussion is on the swap read failures and this patch proposed by Miaohe: https://lore.kernel.org/lkml/20220416030549.60559-1-linmiaohe@xxxxxxxxxx/ So I hope we can still keep them around here under mm/ if possible, and from the gut feeling it really should.. > Would it make sense to have it next to 'config USERFAULTFD' as a > sub-option? Yes another good question. :) IIUC CONFIG_USERFAULTFD resides in init/Kconfig because it introduces a new syscall. Same to the rest of the bits for uffd since then, namely: - USERFAULTFD_WP - USERFAULTFD_MINOR What I am thinking now is the other way round of your suggestion: whether we should move most of them out, at least the _WP and _MINOR configs into mm/? Because IMHO they are really pure mm ideas and they're irrelevant to syscalls and init. Any thoughts? -- Peter Xu
