mirror of
https://github.com/torvalds/linux.git
synced 2024-11-25 13:41:51 +00:00
mm: cleanup follow_page_mask()
Cleanups: - move pte-related code to separate function. It's about half of the function; - get rid of some goto-logic; - use 'return NULL' instead of 'return page' where page can only be NULL; Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Kirill A. Shutemov
Linus Torvalds
parent
f2b495ca82
commit
69e68b4f03
233
mm/gup.c
233
mm/gup.c
@ -12,105 +12,35 @@
|
||||
|
||||
#include "internal.h"
|
||||
|
||||
/**
|
||||
* follow_page_mask - look up a page descriptor from a user-virtual address
|
||||
* @vma: vm_area_struct mapping @address
|
||||
* @address: virtual address to look up
|
||||
* @flags: flags modifying lookup behaviour
|
||||
* @page_mask: on output, *page_mask is set according to the size of the page
|
||||
*
|
||||
* @flags can have FOLL_ flags set, defined in <linux/mm.h>
|
||||
*
|
||||
* Returns the mapped (struct page *), %NULL if no mapping exists, or
|
||||
* an error pointer if there is a mapping to something not represented
|
||||
* by a page descriptor (see also vm_normal_page()).
|
||||
*/
|
||||
struct page *follow_page_mask(struct vm_area_struct *vma,
|
||||
unsigned long address, unsigned int flags,
|
||||
unsigned int *page_mask)
|
||||
static struct page *no_page_table(struct vm_area_struct *vma,
|
||||
unsigned int flags)
|
||||
{
|
||||
/*
|
||||
* When core dumping an enormous anonymous area that nobody
|
||||
* has touched so far, we don't want to allocate unnecessary pages or
|
||||
* page tables. Return error instead of NULL to skip handle_mm_fault,
|
||||
* then get_dump_page() will return NULL to leave a hole in the dump.
|
||||
* But we can only make this optimization where a hole would surely
|
||||
* be zero-filled if handle_mm_fault() actually did handle it.
|
||||
*/
|
||||
if ((flags & FOLL_DUMP) && (!vma->vm_ops || !vma->vm_ops->fault))
|
||||
return ERR_PTR(-EFAULT);
|
||||
return NULL;
|
||||
}
|
||||
|
||||
static struct page *follow_page_pte(struct vm_area_struct *vma,
|
||||
unsigned long address, pmd_t *pmd, unsigned int flags)
|
||||
{
|
||||
pgd_t *pgd;
|
||||
pud_t *pud;
|
||||
pmd_t *pmd;
|
||||
pte_t *ptep, pte;
|
||||
spinlock_t *ptl;
|
||||
struct page *page;
|
||||
struct mm_struct *mm = vma->vm_mm;
|
||||
struct page *page;
|
||||
spinlock_t *ptl;
|
||||
pte_t *ptep, pte;
|
||||
|
||||
*page_mask = 0;
|
||||
|
||||
page = follow_huge_addr(mm, address, flags & FOLL_WRITE);
|
||||
if (!IS_ERR(page)) {
|
||||
BUG_ON(flags & FOLL_GET);
|
||||
goto out;
|
||||
}
|
||||
|
||||
page = NULL;
|
||||
pgd = pgd_offset(mm, address);
|
||||
if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
|
||||
goto no_page_table;
|
||||
|
||||
pud = pud_offset(pgd, address);
|
||||
if (pud_none(*pud))
|
||||
goto no_page_table;
|
||||
if (pud_huge(*pud) && vma->vm_flags & VM_HUGETLB) {
|
||||
if (flags & FOLL_GET)
|
||||
goto out;
|
||||
page = follow_huge_pud(mm, address, pud, flags & FOLL_WRITE);
|
||||
goto out;
|
||||
}
|
||||
if (unlikely(pud_bad(*pud)))
|
||||
goto no_page_table;
|
||||
|
||||
pmd = pmd_offset(pud, address);
|
||||
if (pmd_none(*pmd))
|
||||
goto no_page_table;
|
||||
if (pmd_huge(*pmd) && vma->vm_flags & VM_HUGETLB) {
|
||||
page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE);
|
||||
if (flags & FOLL_GET) {
|
||||
/*
|
||||
* Refcount on tail pages are not well-defined and
|
||||
* shouldn't be taken. The caller should handle a NULL
|
||||
* return when trying to follow tail pages.
|
||||
*/
|
||||
if (PageHead(page))
|
||||
get_page(page);
|
||||
else {
|
||||
page = NULL;
|
||||
goto out;
|
||||
}
|
||||
}
|
||||
goto out;
|
||||
}
|
||||
if ((flags & FOLL_NUMA) && pmd_numa(*pmd))
|
||||
goto no_page_table;
|
||||
if (pmd_trans_huge(*pmd)) {
|
||||
if (flags & FOLL_SPLIT) {
|
||||
split_huge_page_pmd(vma, address, pmd);
|
||||
goto split_fallthrough;
|
||||
}
|
||||
ptl = pmd_lock(mm, pmd);
|
||||
if (likely(pmd_trans_huge(*pmd))) {
|
||||
if (unlikely(pmd_trans_splitting(*pmd))) {
|
||||
spin_unlock(ptl);
|
||||
wait_split_huge_page(vma->anon_vma, pmd);
|
||||
} else {
|
||||
page = follow_trans_huge_pmd(vma, address,
|
||||
pmd, flags);
|
||||
spin_unlock(ptl);
|
||||
*page_mask = HPAGE_PMD_NR - 1;
|
||||
goto out;
|
||||
}
|
||||
} else
|
||||
spin_unlock(ptl);
|
||||
/* fall through */
|
||||
}
|
||||
split_fallthrough:
|
||||
retry:
|
||||
if (unlikely(pmd_bad(*pmd)))
|
||||
goto no_page_table;
|
||||
return no_page_table(vma, flags);
|
||||
|
||||
ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
|
||||
|
||||
pte = *ptep;
|
||||
if (!pte_present(pte)) {
|
||||
swp_entry_t entry;
|
||||
@ -128,12 +58,14 @@ split_fallthrough:
|
||||
goto no_page;
|
||||
pte_unmap_unlock(ptep, ptl);
|
||||
migration_entry_wait(mm, pmd, address);
|
||||
goto split_fallthrough;
|
||||
goto retry;
|
||||
}
|
||||
if ((flags & FOLL_NUMA) && pte_numa(pte))
|
||||
goto no_page;
|
||||
if ((flags & FOLL_WRITE) && !pte_write(pte))
|
||||
goto unlock;
|
||||
if ((flags & FOLL_WRITE) && !pte_write(pte)) {
|
||||
pte_unmap_unlock(ptep, ptl);
|
||||
return NULL;
|
||||
}
|
||||
|
||||
page = vm_normal_page(vma, address, pte);
|
||||
if (unlikely(!page)) {
|
||||
@ -178,11 +110,8 @@ split_fallthrough:
|
||||
unlock_page(page);
|
||||
}
|
||||
}
|
||||
unlock:
|
||||
pte_unmap_unlock(ptep, ptl);
|
||||
out:
|
||||
return page;
|
||||
|
||||
bad_page:
|
||||
pte_unmap_unlock(ptep, ptl);
|
||||
return ERR_PTR(-EFAULT);
|
||||
@ -190,21 +119,99 @@ bad_page:
|
||||
no_page:
|
||||
pte_unmap_unlock(ptep, ptl);
|
||||
if (!pte_none(pte))
|
||||
return page;
|
||||
return NULL;
|
||||
return no_page_table(vma, flags);
|
||||
}
|
||||
|
||||
no_page_table:
|
||||
/*
|
||||
* When core dumping an enormous anonymous area that nobody
|
||||
* has touched so far, we don't want to allocate unnecessary pages or
|
||||
* page tables. Return error instead of NULL to skip handle_mm_fault,
|
||||
* then get_dump_page() will return NULL to leave a hole in the dump.
|
||||
* But we can only make this optimization where a hole would surely
|
||||
* be zero-filled if handle_mm_fault() actually did handle it.
|
||||
*/
|
||||
if ((flags & FOLL_DUMP) &&
|
||||
(!vma->vm_ops || !vma->vm_ops->fault))
|
||||
return ERR_PTR(-EFAULT);
|
||||
return page;
|
||||
/**
|
||||
* follow_page_mask - look up a page descriptor from a user-virtual address
|
||||
* @vma: vm_area_struct mapping @address
|
||||
* @address: virtual address to look up
|
||||
* @flags: flags modifying lookup behaviour
|
||||
* @page_mask: on output, *page_mask is set according to the size of the page
|
||||
*
|
||||
* @flags can have FOLL_ flags set, defined in <linux/mm.h>
|
||||
*
|
||||
* Returns the mapped (struct page *), %NULL if no mapping exists, or
|
||||
* an error pointer if there is a mapping to something not represented
|
||||
* by a page descriptor (see also vm_normal_page()).
|
||||
*/
|
||||
struct page *follow_page_mask(struct vm_area_struct *vma,
|
||||
unsigned long address, unsigned int flags,
|
||||
unsigned int *page_mask)
|
||||
{
|
||||
pgd_t *pgd;
|
||||
pud_t *pud;
|
||||
pmd_t *pmd;
|
||||
spinlock_t *ptl;
|
||||
struct page *page;
|
||||
struct mm_struct *mm = vma->vm_mm;
|
||||
|
||||
*page_mask = 0;
|
||||
|
||||
page = follow_huge_addr(mm, address, flags & FOLL_WRITE);
|
||||
if (!IS_ERR(page)) {
|
||||
BUG_ON(flags & FOLL_GET);
|
||||
return page;
|
||||
}
|
||||
|
||||
pgd = pgd_offset(mm, address);
|
||||
if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
|
||||
return no_page_table(vma, flags);
|
||||
|
||||
pud = pud_offset(pgd, address);
|
||||
if (pud_none(*pud))
|
||||
return no_page_table(vma, flags);
|
||||
if (pud_huge(*pud) && vma->vm_flags & VM_HUGETLB) {
|
||||
if (flags & FOLL_GET)
|
||||
return NULL;
|
||||
page = follow_huge_pud(mm, address, pud, flags & FOLL_WRITE);
|
||||
return page;
|
||||
}
|
||||
if (unlikely(pud_bad(*pud)))
|
||||
return no_page_table(vma, flags);
|
||||
|
||||
pmd = pmd_offset(pud, address);
|
||||
if (pmd_none(*pmd))
|
||||
return no_page_table(vma, flags);
|
||||
if (pmd_huge(*pmd) && vma->vm_flags & VM_HUGETLB) {
|
||||
page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE);
|
||||
if (flags & FOLL_GET) {
|
||||
/*
|
||||
* Refcount on tail pages are not well-defined and
|
||||
* shouldn't be taken. The caller should handle a NULL
|
||||
* return when trying to follow tail pages.
|
||||
*/
|
||||
if (PageHead(page))
|
||||
get_page(page);
|
||||
else
|
||||
page = NULL;
|
||||
}
|
||||
return page;
|
||||
}
|
||||
if ((flags & FOLL_NUMA) && pmd_numa(*pmd))
|
||||
return no_page_table(vma, flags);
|
||||
if (pmd_trans_huge(*pmd)) {
|
||||
if (flags & FOLL_SPLIT) {
|
||||
split_huge_page_pmd(vma, address, pmd);
|
||||
return follow_page_pte(vma, address, pmd, flags);
|
||||
}
|
||||
ptl = pmd_lock(mm, pmd);
|
||||
if (likely(pmd_trans_huge(*pmd))) {
|
||||
if (unlikely(pmd_trans_splitting(*pmd))) {
|
||||
spin_unlock(ptl);
|
||||
wait_split_huge_page(vma->anon_vma, pmd);
|
||||
} else {
|
||||
page = follow_trans_huge_pmd(vma, address,
|
||||
pmd, flags);
|
||||
spin_unlock(ptl);
|
||||
*page_mask = HPAGE_PMD_NR - 1;
|
||||
return page;
|
||||
}
|
||||
} else
|
||||
spin_unlock(ptl);
|
||||
}
|
||||
return follow_page_pte(vma, address, pmd, flags);
|
||||
}
|
||||
|
||||
static inline int stack_guard_page(struct vm_area_struct *vma, unsigned long addr)
|
||||
|
||||
Loading…
Reference in New Issue
Block a user