Le 02/09/2022 à 21:03, Mike Kravetz a écrit : > During discussions of this series [1], it was suggested that hugetlb > handling code in follow_page_mask could be simplified. At the beginning > of follow_page_mask, there currently is a call to follow_huge_addr which > 'may' handle hugetlb pages. ia64 is the only architecture which provides > a follow_huge_addr routine that does not return error. Instead, at each > level of the page table a check is made for a hugetlb entry. If a hugetlb > entry is found, a call to a routine associated with that entry is made. > > Currently, there are two checks for hugetlb entries at each page table > level. The first check is of the form: > if (p?d_huge()) > page = follow_huge_p?d(); > the second check is of the form: > if (is_hugepd()) > page = follow_huge_pd(). > > We can replace these checks, as well as the special handling routines > such as follow_huge_p?d() and follow_huge_pd() with a single routine to > handle hugetlb vmas. > > A new routine hugetlb_follow_page_mask is called for hugetlb vmas at the > beginning of follow_page_mask. hugetlb_follow_page_mask will use the > existing routine huge_pte_offset to walk page tables looking for hugetlb > entries. huge_pte_offset can be overwritten by architectures, and already > handles special cases such as hugepd entries. > > [1] https://lore.kernel.org/linux-mm/cover.1661240170.git.baolin.wang@xxxxxxxxxxxxxxxxx/ > > Suggested-by: David Hildenbrand <david@xxxxxxxxxx> > Signed-off-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx> > --- > v2 - Added WARN_ON_ONCE() and updated comment as suggested by David > Fixed build issue found by kernel test robot > Added vma (pmd sharing) locking to hugetlb_follow_page_mask > ReBased on Baolin's patch to fix issues with CONT_* entries > > arch/ia64/mm/hugetlbpage.c | 15 --- > arch/powerpc/mm/hugetlbpage.c | 37 ------- > include/linux/hugetlb.h | 51 ++-------- > mm/gup.c | 80 +++------------ > mm/hugetlb.c | 182 ++++++++++++---------------------- > 5 files changed, 87 insertions(+), 278 deletions(-) > > diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h > index fe4944f89d34..275e554dd365 100644 > --- a/include/linux/hugetlb.h > +++ b/include/linux/hugetlb.h > @@ -264,6 +255,13 @@ static inline void adjust_range_if_pmd_sharing_possible( > { > } > > +static inline struct page *hugetlb_follow_page_mask(struct vm_area_struct *vma, > + unsigned long address, unsigned int flags) > +{ > + WARN_ON_ONCE(1); /* should never be called if !CONFIG_HUGETLB_PAGE*/ > + return ERR_PTR(-EINVAL); This function is called only when is_vm_hugetlb_page() is true. When !CONFIG_HUGETLB_PAGE is_vm_hugetlb_page() always returns false, so the call to hugetlb_follow_page_mask() should never be compiled in. Use BUILD_BUG() to catch it at buildtime. > +} > + > static inline long follow_hugetlb_page(struct mm_struct *mm, > struct vm_area_struct *vma, struct page **pages, > struct vm_area_struct **vmas, unsigned long *position, > diff --git a/mm/gup.c b/mm/gup.c > index 7691c65233c3..1515892a9d98 100644 > --- a/mm/gup.c > +++ b/mm/gup.c > @@ -530,18 +530,6 @@ static struct page *follow_page_pte(struct vm_area_struct *vma, > if (WARN_ON_ONCE((flags & (FOLL_PIN | FOLL_GET)) == > (FOLL_PIN | FOLL_GET))) > return ERR_PTR(-EINVAL); > - > - /* > - * Considering PTE level hugetlb, like continuous-PTE hugetlb on > - * ARM64 architecture. > - */ > - if (is_vm_hugetlb_page(vma)) { > - page = follow_huge_pmd_pte(vma, address, flags); > - if (page) > - return page; > - return no_page_table(vma, flags); > - } > - > retry: > if (unlikely(pmd_bad(*pmd))) > return no_page_table(vma, flags);
