On Tue, May 12, 2026 at 07:48:57PM +0300, Mike Rapoport wrote: > On Fri, May 08, 2026 at 04:55:16PM +0100, Kiryl Shutsemau (Meta) wrote: > > Preparatory patch for userfaultfd read-write protection (RWP). RWP > > extends userfaultfd protection from plain write-protection (WP) to > > full read-write protection: accesses to an RWP-protected range -- > > reads as well as writes -- trap through userfaultfd. > > > > RWP marks ranges by combining PAGE_NONE with the uffd PTE bit, so > > the flag is only meaningful when both primitives exist. A new > > CONFIG_USERFAULTFD_RWP Kconfig symbol auto-selects when CONFIG_64BIT, > > CONFIG_ARCH_HAS_PTE_PROTNONE, and CONFIG_HAVE_ARCH_USERFAULTFD_WP > > are all set; call sites that gate on the flag depend on the symbol. > > Elsewhere VM_UFFD_RWP aliases VM_NONE and every downstream check > > folds to dead code. > > > > Nothing sets the flag yet. > > And nothing check for it as well, am I right?
Yep. > Worth noting here, IMHO. Will do. > > > Signed-off-by: Kiryl Shutsemau <[email protected]> > > Assisted-by: Claude:claude-opus-4-6 > > --- > > Documentation/filesystems/proc.rst | 1 + > > fs/proc/task_mmu.c | 3 +++ > > include/linux/mm.h | 28 +++++++++++++++++---------- > > include/linux/userfaultfd_k.h | 31 +++++++++++++++++++++++++----- > > include/trace/events/mmflags.h | 7 +++++++ > > mm/Kconfig | 9 +++++++++ > > 6 files changed, 64 insertions(+), 15 deletions(-) > > > > diff --git a/include/linux/userfaultfd_k.h b/include/linux/userfaultfd_k.h > > index 98f546e83cd2..fcf308dba311 100644 > > --- a/include/linux/userfaultfd_k.h > > +++ b/include/linux/userfaultfd_k.h > > @@ -21,10 +21,11 @@ > > #include <linux/hugetlb_inline.h> > > > > /* The set of all possible UFFD-related VM flags. */ > > -#define __VM_UFFD_FLAGS (VM_UFFD_MISSING | VM_UFFD_WP | VM_UFFD_MINOR) > > +#define __VM_UFFD_FLAGS (VM_UFFD_MISSING | VM_UFFD_WP | VM_UFFD_MINOR | \ > > + VM_UFFD_RWP) > > Nit: can we keep mode bits together and protection bits together here and > in the below changes? Yep, make sense. > Otherwise looks good to me > > Reviewed-by: Mike Rapoport (Microsoft) <[email protected]> Thanks! -- Kiryl Shutsemau / Kirill A. Shutemov
