On Sat, Apr 15, 2023 at 12:27:31AM +0100, Lorenzo Stoakes wrote:
> The only instances of get_user_pages_remote() invocations which used the
> vmas parameter were for a single page which can instead simply look up the
> VMA directly. In particular:-
>
> - __update_ref_ctr() looked up the VMA but did nothing with it so we simply
> remove it.
>
> - __access_remote_vm() was already using vma_lookup() when the original
> lookup failed so by doing the lookup directly this also de-duplicates the
> code.
>
> This forms part of a broader set of patches intended to eliminate the vmas
> parameter altogether.
>
> Signed-off-by: Lorenzo Stoakes <lstoakes@xxxxxxxxx>
> ---
> arch/arm64/kernel/mte.c | 5 +++--
> arch/s390/kvm/interrupt.c | 2 +-
> fs/exec.c | 2 +-
> include/linux/mm.h | 2 +-
> kernel/events/uprobes.c | 10 +++++-----
> mm/gup.c | 12 ++++--------
> mm/memory.c | 9 +++++----
> mm/rmap.c | 2 +-
> security/tomoyo/domain.c | 2 +-
> virt/kvm/async_pf.c | 3 +--
> 10 files changed, 23 insertions(+), 26 deletions(-)
>
> diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c
> index f5bcb0dc6267..74d8d4007dec 100644
> --- a/arch/arm64/kernel/mte.c
> +++ b/arch/arm64/kernel/mte.c
> @@ -437,8 +437,9 @@ static int __access_remote_tags(struct mm_struct *mm, unsigned long addr,
> struct page *page = NULL;
>
> ret = get_user_pages_remote(mm, addr, 1, gup_flags, &page,
> - &vma, NULL);
> - if (ret <= 0)
> + NULL);
> + vma = vma_lookup(mm, addr);
> + if (ret <= 0 || !vma)
> break;
Given the slightly tricky error handling, it would make sense to turn
this pattern into a helper function:
page = get_single_user_page_locked(mm, addr, gup_flags, &vma);
if (IS_ERR(page))
[..]
static inline struct page *get_single_user_page_locked(struct mm_struct *mm,
unsigned long addr, int gup_flags, struct vm_area_struct **vma)
{
struct page *page;
int ret;
ret = get_user_pages_remote(*mm, addr, 1, gup_flags, &page, NULL, NULL);
if (ret < 0)
return ERR_PTR(ret);
if (WARN_ON(ret == 0))
return ERR_PTR(-EINVAL);
*vma = vma_lookup(mm, addr);
if (WARN_ON(!*vma) {
put_user_page(page);
return ERR_PTR(-EINVAL);
}
return page;
}
It could be its own patch so this change was just a mechanical removal
of NULL
Jason
