[PATCH 0/4] various improvements to the GUP interface

From: Lorenzo Stoakes
Date: Sun Oct 01 2023 - 12:00:30 EST


A series of fixes to simplify and improve the GUP interface with an eye to
providing groundwork to future improvements:-

* __access_remote_vm() and access_remote_vm() are functionally identical,
so make the former static such that in future we can potentially change
the external-facing implementation details of this function.

* Extend is_valid_gup_args() to cover the missing FOLL_TOUCH case, and
simplify things by defining INTERNAL_GUP_FLAGS to check against.

* Adjust __get_user_pages_locked() to explicitly treat a failure to pin any
pages as an error in all circumstances other than FOLL_NOWAIT being
specified, bringing it in line with the nommu implementation of this
function.

* (With many thanks to Arnd who suggested this in the first instance)
Update get_user_page_vma_remote() to explicitly only return a page or an
error, simplifying the interface and avoiding the questionable
IS_ERR_OR_NULL() pattern.

Lorenzo Stoakes (4):
mm: make __access_remote_vm() static
mm/gup: explicitly define and check internal GUP flags, disallow
FOLL_TOUCH
mm/gup: make failure to pin an error if FOLL_NOWAIT not specified
mm/gup: adapt get_user_page_vma_remote() to never return NULL

arch/arm64/kernel/mte.c | 4 ++--
include/linux/mm.h | 18 +++++++++++++-----
kernel/events/uprobes.c | 4 ++--
kernel/ptrace.c | 2 +-
mm/gup.c | 16 +++++++++++++---
mm/internal.h | 3 +++
mm/memory.c | 7 +++----
mm/nommu.c | 4 ++--
8 files changed, 39 insertions(+), 19 deletions(-)

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2.42.0