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Subject[PATCH v2] mm: Remove src/dst mm parameter in copy_page_range()
Date
Both of the mm pointers are not needed after commit 7a4830c380f3 ("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.

CC: Jason Gunthorpe <jgg@ziepe.ca>
CC: Andrew Morton <akpm@linux-foundation.org>
Reported-by: Kirill A. Shutemov <kirill@shutemov.name>
Signed-off-by: Peter Xu <peterx@redhat.com>
---
v2:
- further reorder some parameters and line format [Jason]
---
include/linux/mm.h | 4 +-
kernel/fork.c | 2 +-
mm/memory.c | 139 ++++++++++++++++++++++++---------------------
3 files changed, 76 insertions(+), 69 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 16b799a0522c..a26e9f706b25 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1645,8 +1645,8 @@ 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);
diff --git a/kernel/fork.c b/kernel/fork.c
index da8d360fb032..a7671f5cb3e1 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -589,7 +589,7 @@ 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);
diff --git a/mm/memory.c b/mm/memory.c
index fcfc4ca36eba..8ade87e8600a 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -794,15 +794,15 @@ 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 *dst_mm = dst_vma->vm_mm;
+ 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;

/*
@@ -865,15 +865,15 @@ 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);
+ pte = mk_pte(new_page, dst_vma->vm_page_prot);
+ pte = maybe_mkwrite(pte_mkdirty(pte), dst_vma);
set_pte_at(dst_mm, addr, dst_pte, pte);
return 0;
}
@@ -883,24 +883,22 @@ 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 *dst_mm = dst_vma->vm_mm;
+ 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;

@@ -957,11 +955,13 @@ 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;
@@ -1004,15 +1004,15 @@ 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.
@@ -1047,7 +1047,7 @@ 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. */
@@ -1061,11 +1061,13 @@ 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;

@@ -1078,9 +1080,9 @@ 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)
@@ -1089,18 +1091,20 @@ 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;

@@ -1113,9 +1117,9 @@ 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)
@@ -1124,18 +1128,19 @@ 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;

@@ -1147,20 +1152,22 @@ 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;
@@ -1171,19 +1178,19 @@ 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;
}
@@ -1194,11 +1201,11 @@ 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);
}

@@ -1209,8 +1216,8 @@ 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;
}
--
2.26.2
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