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userfaultfd: hugetlbfs: add hugetlb_mcopy_atomic_pte for userfaultfd support 

hugetlb_mcopy_atomic_pte is the low level routine that implements the
userfaultfd UFFDIO_COPY command.  It is based on the existing
mcopy_atomic_pte routine with modifications for huge pages.

Link: http://lkml.kernel.org/r/20161216144821.5183-18-aarcange@redhat.com
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Michael Rapoport <RAPOPORT@il.ibm.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Mike Kravetz 2017-02-22 15:42:52 -08:00 committed by Linus Torvalds
parent fa4d75c1de
commit 8fb5debc5f
2 changed files with 88 additions and 0 deletions
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7
include/linux/hugetlb.h
View File

@ -81,6 +81,11 @@ void hugetlb_show_meminfo(void);
unsigned long hugetlb_total_pages(void);
int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long address, unsigned int flags);
int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm, pte_t *dst_pte,
struct vm_area_struct *dst_vma,
unsigned long dst_addr,
unsigned long src_addr,
struct page **pagep);
int hugetlb_reserve_pages(struct inode *inode, long from, long to,
struct vm_area_struct *vma,
vm_flags_t vm_flags);
@ -149,6 +154,8 @@ static inline void hugetlb_show_meminfo(void)
#define is_hugepage_only_range(mm, addr, len) 0
#define hugetlb_free_pgd_range(tlb, addr, end, floor, ceiling) ({BUG(); 0; })
#define hugetlb_fault(mm, vma, addr, flags) ({ BUG(); 0; })
#define hugetlb_mcopy_atomic_pte(dst_mm, dst_pte, dst_vma, dst_addr, \
src_addr, pagep) ({ BUG(); 0; })
#define huge_pte_offset(mm, address) 0
static inline int dequeue_hwpoisoned_huge_page(struct page *page)
{

81
mm/hugetlb.c
View File

@ -3948,6 +3948,87 @@ out_mutex:
return ret;
}
/*
* Used by userfaultfd UFFDIO_COPY. Based on mcopy_atomic_pte with
* modifications for huge pages.
*/
int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm,
pte_t *dst_pte,
struct vm_area_struct *dst_vma,
unsigned long dst_addr,
unsigned long src_addr,
struct page **pagep)
{
struct hstate *h = hstate_vma(dst_vma);
pte_t _dst_pte;
spinlock_t *ptl;
int ret;
struct page *page;
if (!*pagep) {
ret = -ENOMEM;
page = alloc_huge_page(dst_vma, dst_addr, 0);
if (IS_ERR(page))
goto out;
ret = copy_huge_page_from_user(page,
(const void __user *) src_addr,
pages_per_huge_page(h));
/* fallback to copy_from_user outside mmap_sem */
if (unlikely(ret)) {
ret = -EFAULT;
*pagep = page;
/* don't free the page */
goto out;
}
} else {
page = *pagep;
*pagep = NULL;
}
/*
* The memory barrier inside __SetPageUptodate makes sure that
* preceding stores to the page contents become visible before
* the set_pte_at() write.
*/
__SetPageUptodate(page);
set_page_huge_active(page);
ptl = huge_pte_lockptr(h, dst_mm, dst_pte);
spin_lock(ptl);
ret = -EEXIST;
if (!huge_pte_none(huge_ptep_get(dst_pte)))
goto out_release_unlock;
ClearPagePrivate(page);
hugepage_add_new_anon_rmap(page, dst_vma, dst_addr);
_dst_pte = make_huge_pte(dst_vma, page, dst_vma->vm_flags & VM_WRITE);
if (dst_vma->vm_flags & VM_WRITE)
_dst_pte = huge_pte_mkdirty(_dst_pte);
_dst_pte = pte_mkyoung(_dst_pte);
set_huge_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte);
(void)huge_ptep_set_access_flags(dst_vma, dst_addr, dst_pte, _dst_pte,
dst_vma->vm_flags & VM_WRITE);
hugetlb_count_add(pages_per_huge_page(h), dst_mm);
/* No need to invalidate - it was non-present before */
update_mmu_cache(dst_vma, dst_addr, dst_pte);
spin_unlock(ptl);
ret = 0;
out:
return ret;
out_release_unlock:
spin_unlock(ptl);
put_page(page);
goto out;
}
long follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
struct page **pages, struct vm_area_struct **vmas,
unsigned long *position, unsigned long *nr_pages,