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thp: mprotect: transparent huge page support 

Natively handle huge pmds when changing page tables on behalf of
mprotect().

I left out update_mmu_cache() because we do not need it on x86 anyway but
more importantly the interface works on ptes, not pmds.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Johannes Weiner 2011-01-13 15:47:04 -08:00 committed by Linus Torvalds
parent b36f5b0710
commit cd7548ab36
3 changed files with 36 additions and 1 deletions
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2
include/linux/huge_mm.h
View File

@ -22,6 +22,8 @@ extern int zap_huge_pmd(struct mmu_gather *tlb,
extern int mincore_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
unsigned long addr, unsigned long end,
unsigned char *vec);
extern int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
unsigned long addr, pgprot_t newprot);
enum transparent_hugepage_flag {
TRANSPARENT_HUGEPAGE_FLAG,

27
mm/huge_memory.c
View File

@ -948,6 +948,33 @@ int mincore_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
return ret;
}
int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
unsigned long addr, pgprot_t newprot)
{
struct mm_struct *mm = vma->vm_mm;
int ret = 0;
spin_lock(&mm->page_table_lock);
if (likely(pmd_trans_huge(*pmd))) {
if (unlikely(pmd_trans_splitting(*pmd))) {
spin_unlock(&mm->page_table_lock);
wait_split_huge_page(vma->anon_vma, pmd);
} else {
pmd_t entry;
entry = pmdp_get_and_clear(mm, addr, pmd);
entry = pmd_modify(entry, newprot);
set_pmd_at(mm, addr, pmd, entry);
spin_unlock(&vma->vm_mm->page_table_lock);
flush_tlb_range(vma, addr, addr + HPAGE_PMD_SIZE);
ret = 1;
}
} else
spin_unlock(&vma->vm_mm->page_table_lock);
return ret;
}
pmd_t *page_check_address_pmd(struct page *page,
struct mm_struct *mm,
unsigned long address,

8
mm/mprotect.c
View File

@ -88,7 +88,13 @@ static inline void change_pmd_range(struct vm_area_struct *vma, pud_t *pud,
pmd = pmd_offset(pud, addr);
do {
next = pmd_addr_end(addr, end);
split_huge_page_pmd(vma->vm_mm, pmd);
if (pmd_trans_huge(*pmd)) {
if (next - addr != HPAGE_PMD_SIZE)
split_huge_page_pmd(vma->vm_mm, pmd);
else if (change_huge_pmd(vma, pmd, addr, newprot))
continue;
/* fall through */
}
if (pmd_none_or_clear_bad(pmd))
continue;
change_pte_range(vma->vm_mm, pmd, addr, next, newprot,