[PATCH v3 08/48] mm/mmap: convert brk to use vma iterator

Liam Howlett
2023-01-17T02:35:20Z

Use the vma iterator API for the brk() system call. This will provide
type safety at compile time.

Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
---
mm/mmap.c | 46 ++++++++++++++++++++++------------------------
1 file changed, 22 insertions(+), 24 deletions(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index 024fb46251e2..81ff47147317 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -180,10 +180,10 @@ static int check_brk_limits(unsigned long addr, unsigned long len)

return mlock_future_check(current->mm, current->mm->def_flags, len);
}
-static int do_brk_munmap(struct ma_state *mas, struct vm_area_struct *vma,
+static int do_brk_munmap(struct vma_iterator *vmi, struct vm_area_struct *vma,
unsigned long newbrk, unsigned long oldbrk,
struct list_head *uf);
-static int do_brk_flags(struct ma_state *mas, struct vm_area_struct *brkvma,
+static int do_brk_flags(struct vma_iterator *vmi, struct vm_area_struct *brkvma,
unsigned long addr, unsigned long request, unsigned long flags);
SYSCALL_DEFINE1(brk, unsigned long, brk)
{
@@ -194,7 +194,7 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
bool populate;
bool downgraded = false;
LIST_HEAD(uf);
- MA_STATE(mas, &mm->mm_mt, 0, 0);
+ struct vma_iterator vmi;

if (mmap_write_lock_killable(mm))
return -EINTR;
@@ -242,8 +242,8 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
int ret;

/* Search one past newbrk */
- mas_set(&mas, newbrk);
- brkvma = mas_find(&mas, oldbrk);
+ vma_iter_init(&vmi, mm, newbrk);
+ brkvma = vma_find(&vmi, oldbrk);
if (!brkvma || brkvma->vm_start >= oldbrk)
goto out; /* mapping intersects with an existing non-brk vma. */
/*
@@ -252,7 +252,7 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
* before calling do_brk_munmap().
*/
mm->brk = brk;
- ret = do_brk_munmap(&mas, brkvma, newbrk, oldbrk, &uf);
+ ret = do_brk_munmap(&vmi, brkvma, newbrk, oldbrk, &uf);
if (ret == 1) {
downgraded = true;
goto success;
@@ -270,14 +270,14 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
* Only check if the next VMA is within the stack_guard_gap of the
* expansion area
*/
- mas_set(&mas, oldbrk);
- next = mas_find(&mas, newbrk - 1 + PAGE_SIZE + stack_guard_gap);
+ vma_iter_init(&vmi, mm, oldbrk);
+ next = vma_find(&vmi, newbrk + PAGE_SIZE + stack_guard_gap);
if (next && newbrk + PAGE_SIZE > vm_start_gap(next))
goto out;

- brkvma = mas_prev(&mas, mm->start_brk);
+ brkvma = vma_prev_limit(&vmi, mm->start_brk);
/* Ok, looks good - let it rip. */
- if (do_brk_flags(&mas, brkvma, oldbrk, newbrk - oldbrk, 0) < 0)
+ if (do_brk_flags(&vmi, brkvma, oldbrk, newbrk - oldbrk, 0) < 0)
goto out;

mm->brk = brk;
@@ -2904,7 +2904,7 @@ SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,

/*
* brk_munmap() - Unmap a parital vma.
- * @mas: The maple tree state.
+ * @vmi: The vma iterator
* @vma: The vma to be modified
* @newbrk: the start of the address to unmap
* @oldbrk: The end of the address to unmap
@@ -2914,7 +2914,7 @@ SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,
* unmaps a partial VMA mapping. Does not handle alignment, downgrades lock if
* possible.
*/
-static int do_brk_munmap(struct ma_state *mas, struct vm_area_struct *vma,
+static int do_brk_munmap(struct vma_iterator *vmi, struct vm_area_struct *vma,
unsigned long newbrk, unsigned long oldbrk,
struct list_head *uf)
{
@@ -2922,14 +2922,14 @@ static int do_brk_munmap(struct ma_state *mas, struct vm_area_struct *vma,
int ret;

arch_unmap(mm, newbrk, oldbrk);
- ret = do_mas_align_munmap(mas, vma, mm, newbrk, oldbrk, uf, true);
+ ret = do_mas_align_munmap(&vmi->mas, vma, mm, newbrk, oldbrk, uf, true);
validate_mm_mt(mm);
return ret;
}

/*
* do_brk_flags() - Increase the brk vma if the flags match.
- * @mas: The maple tree state.
+ * @vmi: The vma iterator
* @addr: The start address
* @len: The length of the increase
* @vma: The vma,
@@ -2939,7 +2939,7 @@ static int do_brk_munmap(struct ma_state *mas, struct vm_area_struct *vma,
* do not match then create a new anonymous VMA. Eventually we may be able to
* do some brk-specific accounting here.
*/
-static int do_brk_flags(struct ma_state *mas, struct vm_area_struct *vma,
+static int do_brk_flags(struct vma_iterator *vmi, struct vm_area_struct *vma,
unsigned long addr, unsigned long len, unsigned long flags)
{
struct mm_struct *mm = current->mm;
@@ -2966,8 +2966,7 @@ static int do_brk_flags(struct ma_state *mas, struct vm_area_struct *vma,
if (vma && vma->vm_end == addr && !vma_policy(vma) &&
can_vma_merge_after(vma, flags, NULL, NULL,
addr >> PAGE_SHIFT, NULL_VM_UFFD_CTX, NULL)) {
- mas_set_range(mas, vma->vm_start, addr + len - 1);
- if (mas_preallocate(mas, vma, GFP_KERNEL))
+ if (vma_iter_prealloc(vmi, vma))
goto unacct_fail;

vma_adjust_trans_huge(vma, vma->vm_start, addr + len, 0);
@@ -2977,7 +2976,7 @@ static int do_brk_flags(struct ma_state *mas, struct vm_area_struct *vma,
}
vma->vm_end = addr + len;
vma->vm_flags |= VM_SOFTDIRTY;
- mas_store_prealloc(mas, vma);
+ vma_iter_store(vmi, vma);

if (vma->anon_vma) {
anon_vma_interval_tree_post_update_vma(vma);
@@ -2998,8 +2997,7 @@ static int do_brk_flags(struct ma_state *mas, struct vm_area_struct *vma,
vma->vm_pgoff = addr >> PAGE_SHIFT;
vma->vm_flags = flags;
vma->vm_page_prot = vm_get_page_prot(flags);
- mas_set_range(mas, vma->vm_start, addr + len - 1);
- if (mas_store_gfp(mas, vma, GFP_KERNEL))
+ if (vma_iter_store_gfp(vmi, vma, GFP_KERNEL))
goto mas_store_fail;

mm->map_count++;
@@ -3028,7 +3026,7 @@ int vm_brk_flags(unsigned long addr, unsigned long request, unsigned long flags)
int ret;
bool populate;
LIST_HEAD(uf);
- MA_STATE(mas, &mm->mm_mt, addr, addr);
+ VMA_ITERATOR(vmi, mm, addr);

len = PAGE_ALIGN(request);
if (len < request)
@@ -3047,12 +3045,12 @@ int vm_brk_flags(unsigned long addr, unsigned long request, unsigned long flags)
if (ret)
goto limits_failed;

- ret = do_mas_munmap(&mas, mm, addr, len, &uf, 0);
+ ret = do_mas_munmap(&vmi.mas, mm, addr, len, &uf, 0);
if (ret)
goto munmap_failed;

- vma = mas_prev(&mas, 0);
- ret = do_brk_flags(&mas, vma, addr, len, flags);
+ vma = vma_prev(&vmi);
+ ret = do_brk_flags(&vmi, vma, addr, len, flags);
populate = ((mm->def_flags & VM_LOCKED) != 0);
mmap_write_unlock(mm);
userfaultfd_unmap_complete(mm, &uf);
--
2.35.1