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Code Issues Releases Wiki Activity

mm: remove src/dst mm parameter in copy_page_range()

Browse source 
Both of the mm pointers are not needed after commit 7a4830c380
("mm/fork: Pass new vma pointer into copy_page_range()").

Jason Gunthorpe also reported that the ordering of copy_page_range() is
odd.  Since working at it, reorder the parameters to be logical, by (1)
always put the dst_* fields to be before src_* fields, and (2) keep the
same type of parameters together.

[peterx@redhat.com: further reorder some parameters and line format, per Jason]
  Link: https://lkml.kernel.org/r/20201002192647.7161-1-peterx@redhat.com
[peterx@redhat.com: fix warnings]
  Link: https://lkml.kernel.org/r/20201006200138.GA6026@xz-x1

Reported-by: Kirill A. Shutemov <kirill@shutemov.name>
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Link: https://lkml.kernel.org/r/20200930204950.6668-1-peterx@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Peter Xu 2020-10-13 16:54:21 -07:00 committed by Linus Torvalds
parent 8332326e8e
commit c78f463649
3 changed files with 76 additions and 71 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

4
include/linux/mm.h
View file

@ -1653,8 +1653,8 @@ struct mmu_notifier_range;
void free_pgd_range(struct mmu_gather *tlb, unsigned long addr,
unsigned long end, unsigned long floor, unsigned long ceiling);
int copy_page_range(struct mm_struct *dst, struct mm_struct *src,
struct vm_area_struct *vma, struct vm_area_struct *new);
int
copy_page_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma);
int follow_pte_pmd(struct mm_struct *mm, unsigned long address,
struct mmu_notifier_range *range,
pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp);

2
kernel/fork.c
View file

@ -590,7 +590,7 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm,
mm->map_count++;
if (!(tmp->vm_flags & VM_WIPEONFORK))
retval = copy_page_range(mm, oldmm, mpnt, tmp);
retval = copy_page_range(tmp, mpnt);
if (tmp->vm_ops && tmp->vm_ops->open)
tmp->vm_ops->open(tmp);

141
mm/memory.c
View file

@ -794,15 +794,14 @@ copy_nonpresent_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
* lock.
*/
static inline int
copy_present_page(struct mm_struct *dst_mm, struct mm_struct *src_mm,
pte_t *dst_pte, pte_t *src_pte,
struct vm_area_struct *vma, struct vm_area_struct *new,
unsigned long addr, int *rss, struct page **prealloc,
pte_t pte, struct page *page)
copy_present_page(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
pte_t *dst_pte, pte_t *src_pte, unsigned long addr, int *rss,
struct page **prealloc, pte_t pte, struct page *page)
{
struct mm_struct *src_mm = src_vma->vm_mm;
struct page *new_page;
if (!is_cow_mapping(vma->vm_flags))
if (!is_cow_mapping(src_vma->vm_flags))
return 1;
/*
@ -832,16 +831,16 @@ copy_present_page(struct mm_struct *dst_mm, struct mm_struct *src_mm,
* over and copy the page & arm it.
*/
*prealloc = NULL;
copy_user_highpage(new_page, page, addr, vma);
copy_user_highpage(new_page, page, addr, src_vma);
__SetPageUptodate(new_page);
page_add_new_anon_rmap(new_page, new, addr, false);
lru_cache_add_inactive_or_unevictable(new_page, new);
page_add_new_anon_rmap(new_page, dst_vma, addr, false);
lru_cache_add_inactive_or_unevictable(new_page, dst_vma);
rss[mm_counter(new_page)]++;
/* All done, just insert the new page copy in the child */
pte = mk_pte(new_page, new->vm_page_prot);
pte = maybe_mkwrite(pte_mkdirty(pte), new);
set_pte_at(dst_mm, addr, dst_pte, pte);
pte = mk_pte(new_page, dst_vma->vm_page_prot);
pte = maybe_mkwrite(pte_mkdirty(pte), dst_vma);
set_pte_at(dst_vma->vm_mm, addr, dst_pte, pte);
return 0;
}
@ -850,24 +849,21 @@ copy_present_page(struct mm_struct *dst_mm, struct mm_struct *src_mm,
* is required to copy this pte.
*/
static inline int
copy_present_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
struct vm_area_struct *new,
unsigned long addr, int *rss, struct page **prealloc)
copy_present_pte(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
pte_t *dst_pte, pte_t *src_pte, unsigned long addr, int *rss,
struct page **prealloc)
{
unsigned long vm_flags = vma->vm_flags;
struct mm_struct *src_mm = src_vma->vm_mm;
unsigned long vm_flags = src_vma->vm_flags;
pte_t pte = *src_pte;
struct page *page;
page = vm_normal_page(vma, addr, pte);
page = vm_normal_page(src_vma, addr, pte);
if (page) {
int retval;
retval = copy_present_page(dst_mm, src_mm,
dst_pte, src_pte,
vma, new,
addr, rss, prealloc,
pte, page);
retval = copy_present_page(dst_vma, src_vma, dst_pte, src_pte,
addr, rss, prealloc, pte, page);
if (retval <= 0)
return retval;
@ -901,7 +897,7 @@ copy_present_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
if (!(vm_flags & VM_UFFD_WP))
pte = pte_clear_uffd_wp(pte);
set_pte_at(dst_mm, addr, dst_pte, pte);
set_pte_at(dst_vma->vm_mm, addr, dst_pte, pte);
return 0;
}
@ -924,11 +920,13 @@ page_copy_prealloc(struct mm_struct *src_mm, struct vm_area_struct *vma,
return new_page;
}
static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
struct vm_area_struct *new,
unsigned long addr, unsigned long end)
static int
copy_pte_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
unsigned long end)
{
struct mm_struct *dst_mm = dst_vma->vm_mm;
struct mm_struct *src_mm = src_vma->vm_mm;
pte_t *orig_src_pte, *orig_dst_pte;
pte_t *src_pte, *dst_pte;
spinlock_t *src_ptl, *dst_ptl;
@ -971,15 +969,15 @@ static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
if (unlikely(!pte_present(*src_pte))) {
entry.val = copy_nonpresent_pte(dst_mm, src_mm,
dst_pte, src_pte,
vma, addr, rss);
src_vma, addr, rss);
if (entry.val)
break;
progress += 8;
continue;
}
/* copy_present_pte() will clear `*prealloc' if consumed */
ret = copy_present_pte(dst_mm, src_mm, dst_pte, src_pte,
vma, new, addr, rss, &prealloc);
ret = copy_present_pte(dst_vma, src_vma, dst_pte, src_pte,
addr, rss, &prealloc);
/*
* If we need a pre-allocated page for this pte, drop the
* locks, allocate, and try again.
@ -1014,7 +1012,7 @@ static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
entry.val = 0;
} else if (ret) {
WARN_ON_ONCE(ret != -EAGAIN);
prealloc = page_copy_prealloc(src_mm, vma, addr);
prealloc = page_copy_prealloc(src_mm, src_vma, addr);
if (!prealloc)
return -ENOMEM;
/* We've captured and resolved the error. Reset, try again. */
@ -1028,11 +1026,13 @@ static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
return ret;
}
static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma,
struct vm_area_struct *new,
unsigned long addr, unsigned long end)
static inline int
copy_pmd_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
pud_t *dst_pud, pud_t *src_pud, unsigned long addr,
unsigned long end)
{
struct mm_struct *dst_mm = dst_vma->vm_mm;
struct mm_struct *src_mm = src_vma->vm_mm;
pmd_t *src_pmd, *dst_pmd;
unsigned long next;
@ -1045,9 +1045,9 @@ static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src
if (is_swap_pmd(*src_pmd) || pmd_trans_huge(*src_pmd)
|| pmd_devmap(*src_pmd)) {
int err;
VM_BUG_ON_VMA(next-addr != HPAGE_PMD_SIZE, vma);
VM_BUG_ON_VMA(next-addr != HPAGE_PMD_SIZE, src_vma);
err = copy_huge_pmd(dst_mm, src_mm,
dst_pmd, src_pmd, addr, vma);
dst_pmd, src_pmd, addr, src_vma);
if (err == -ENOMEM)
return -ENOMEM;
if (!err)
@ -1056,18 +1056,20 @@ static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src
}
if (pmd_none_or_clear_bad(src_pmd))
continue;
if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
vma, new, addr, next))
if (copy_pte_range(dst_vma, src_vma, dst_pmd, src_pmd,
addr, next))
return -ENOMEM;
} while (dst_pmd++, src_pmd++, addr = next, addr != end);
return 0;
}
static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
p4d_t *dst_p4d, p4d_t *src_p4d, struct vm_area_struct *vma,
struct vm_area_struct *new,
unsigned long addr, unsigned long end)
static inline int
copy_pud_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
p4d_t *dst_p4d, p4d_t *src_p4d, unsigned long addr,
unsigned long end)
{
struct mm_struct *dst_mm = dst_vma->vm_mm;
struct mm_struct *src_mm = src_vma->vm_mm;
pud_t *src_pud, *dst_pud;
unsigned long next;
@ -1080,9 +1082,9 @@ static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src
if (pud_trans_huge(*src_pud) || pud_devmap(*src_pud)) {
int err;
VM_BUG_ON_VMA(next-addr != HPAGE_PUD_SIZE, vma);
VM_BUG_ON_VMA(next-addr != HPAGE_PUD_SIZE, src_vma);
err = copy_huge_pud(dst_mm, src_mm,
dst_pud, src_pud, addr, vma);
dst_pud, src_pud, addr, src_vma);
if (err == -ENOMEM)
return -ENOMEM;
if (!err)
@ -1091,18 +1093,19 @@ static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src
}
if (pud_none_or_clear_bad(src_pud))
continue;
if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
vma, new, addr, next))
if (copy_pmd_range(dst_vma, src_vma, dst_pud, src_pud,
addr, next))
return -ENOMEM;
} while (dst_pud++, src_pud++, addr = next, addr != end);
return 0;
}
static inline int copy_p4d_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma,
struct vm_area_struct *new,
unsigned long addr, unsigned long end)
static inline int
copy_p4d_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
pgd_t *dst_pgd, pgd_t *src_pgd, unsigned long addr,
unsigned long end)
{
struct mm_struct *dst_mm = dst_vma->vm_mm;
p4d_t *src_p4d, *dst_p4d;
unsigned long next;
@ -1114,20 +1117,22 @@ static inline int copy_p4d_range(struct mm_struct *dst_mm, struct mm_struct *src
next = p4d_addr_end(addr, end);
if (p4d_none_or_clear_bad(src_p4d))
continue;
if (copy_pud_range(dst_mm, src_mm, dst_p4d, src_p4d,
vma, new, addr, next))
if (copy_pud_range(dst_vma, src_vma, dst_p4d, src_p4d,
addr, next))
return -ENOMEM;
} while (dst_p4d++, src_p4d++, addr = next, addr != end);
return 0;
}
int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
struct vm_area_struct *vma, struct vm_area_struct *new)
int
copy_page_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma)
{
pgd_t *src_pgd, *dst_pgd;
unsigned long next;
unsigned long addr = vma->vm_start;
unsigned long end = vma->vm_end;
unsigned long addr = src_vma->vm_start;
unsigned long end = src_vma->vm_end;
struct mm_struct *dst_mm = dst_vma->vm_mm;
struct mm_struct *src_mm = src_vma->vm_mm;
struct mmu_notifier_range range;
bool is_cow;
int ret;
@ -1138,19 +1143,19 @@ int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
* readonly mappings. The tradeoff is that copy_page_range is more
* efficient than faulting.
*/
if (!(vma->vm_flags & (VM_HUGETLB | VM_PFNMAP | VM_MIXEDMAP)) &&
!vma->anon_vma)
if (!(src_vma->vm_flags & (VM_HUGETLB | VM_PFNMAP | VM_MIXEDMAP)) &&
!src_vma->anon_vma)
return 0;
if (is_vm_hugetlb_page(vma))
return copy_hugetlb_page_range(dst_mm, src_mm, vma);
if (is_vm_hugetlb_page(src_vma))
return copy_hugetlb_page_range(dst_mm, src_mm, src_vma);
if (unlikely(vma->vm_flags & VM_PFNMAP)) {
if (unlikely(src_vma->vm_flags & VM_PFNMAP)) {
/*
* We do not free on error cases below as remove_vma
* gets called on error from higher level routine
*/
ret = track_pfn_copy(vma);
ret = track_pfn_copy(src_vma);
if (ret)
return ret;
}
@ -1161,11 +1166,11 @@ int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
* parent mm. And a permission downgrade will only happen if
* is_cow_mapping() returns true.
*/
is_cow = is_cow_mapping(vma->vm_flags);
is_cow = is_cow_mapping(src_vma->vm_flags);
if (is_cow) {
mmu_notifier_range_init(&range, MMU_NOTIFY_PROTECTION_PAGE,
0, vma, src_mm, addr, end);
0, src_vma, src_mm, addr, end);
mmu_notifier_invalidate_range_start(&range);
}
@ -1176,8 +1181,8 @@ int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
next = pgd_addr_end(addr, end);
if (pgd_none_or_clear_bad(src_pgd))
continue;
if (unlikely(copy_p4d_range(dst_mm, src_mm, dst_pgd, src_pgd,
vma, new, addr, next))) {
if (unlikely(copy_p4d_range(dst_vma, src_vma, dst_pgd, src_pgd,
addr, next))) {
ret = -ENOMEM;
break;
}