[PATCH v3 18/48] mlock: Convert mlock to vma iterator

Liam Howlett
2023-01-17T02:37:19Z

Use the vma iterator so that the iterator can be invalidated or updated
to avoid each caller doing so.

Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
---
mm/mlock.c | 57 +++++++++++++++++++++++++++---------------------------
1 file changed, 28 insertions(+), 29 deletions(-)

diff --git a/mm/mlock.c b/mm/mlock.c
index 7032f6dd0ce1..35764a4f0575 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -401,8 +401,9 @@ static void mlock_vma_pages_range(struct vm_area_struct *vma,
*
* For vmas that pass the filters, merge/split as appropriate.
*/
-static int mlock_fixup(struct vm_area_struct *vma, struct vm_area_struct **prev,
- unsigned long start, unsigned long end, vm_flags_t newflags)
+static int mlock_fixup(struct vma_iterator *vmi, struct vm_area_struct *vma,
+ struct vm_area_struct **prev, unsigned long start,
+ unsigned long end, vm_flags_t newflags)
{
struct mm_struct *mm = vma->vm_mm;
pgoff_t pgoff;
@@ -417,22 +418,22 @@ static int mlock_fixup(struct vm_area_struct *vma, struct vm_area_struct **prev,
goto out;

pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
- *prev = vma_merge(mm, *prev, start, end, newflags, vma->anon_vma,
- vma->vm_file, pgoff, vma_policy(vma),
- vma->vm_userfaultfd_ctx, anon_vma_name(vma));
+ *prev = vmi_vma_merge(vmi, mm, *prev, start, end, newflags,
+ vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma),
+ vma->vm_userfaultfd_ctx, anon_vma_name(vma));
if (*prev) {
vma = *prev;
goto success;
}

if (start != vma->vm_start) {
- ret = split_vma(mm, vma, start, 1);
+ ret = vmi_split_vma(vmi, mm, vma, start, 1);
if (ret)
goto out;
}

if (end != vma->vm_end) {
- ret = split_vma(mm, vma, end, 0);
+ ret = vmi_split_vma(vmi, mm, vma, end, 0);
if (ret)
goto out;
}
@@ -471,7 +472,7 @@ static int apply_vma_lock_flags(unsigned long start, size_t len,
unsigned long nstart, end, tmp;
struct vm_area_struct *vma, *prev;
int error;
- MA_STATE(mas, &current->mm->mm_mt, start, start);
+ VMA_ITERATOR(vmi, current->mm, start);

VM_BUG_ON(offset_in_page(start));
VM_BUG_ON(len != PAGE_ALIGN(len));
@@ -480,39 +481,37 @@ static int apply_vma_lock_flags(unsigned long start, size_t len,
return -EINVAL;
if (end == start)
return 0;
- vma = mas_walk(&mas);
+ vma = vma_iter_load(&vmi);
if (!vma)
return -ENOMEM;

+ prev = vma_prev(&vmi);
if (start > vma->vm_start)
prev = vma;
- else
- prev = mas_prev(&mas, 0);

- for (nstart = start ; ; ) {
- vm_flags_t newflags = vma->vm_flags & VM_LOCKED_CLEAR_MASK;
+ nstart = start;
+ tmp = vma->vm_start;
+ for_each_vma_range(vmi, vma, end) {
+ vm_flags_t newflags;

- newflags |= flags;
+ if (vma->vm_start != tmp)
+ return -ENOMEM;

+ newflags = vma->vm_flags & VM_LOCKED_CLEAR_MASK;
+ newflags |= flags;
/* Here we know that vma->vm_start <= nstart < vma->vm_end. */
tmp = vma->vm_end;
if (tmp > end)
tmp = end;
- error = mlock_fixup(vma, &prev, nstart, tmp, newflags);
+ error = mlock_fixup(&vmi, vma, &prev, nstart, tmp, newflags);
if (error)
break;
nstart = tmp;
- if (nstart < prev->vm_end)
- nstart = prev->vm_end;
- if (nstart >= end)
- break;
-
- vma = find_vma(prev->vm_mm, prev->vm_end);
- if (!vma || vma->vm_start != nstart) {
- error = -ENOMEM;
- break;
- }
}
+
+ if (vma_iter_end(&vmi) < end)
+ return -ENOMEM;
+
return error;
}

@@ -658,7 +657,7 @@ SYSCALL_DEFINE2(munlock, unsigned long, start, size_t, len)
*/
static int apply_mlockall_flags(int flags)
{
- MA_STATE(mas, &current->mm->mm_mt, 0, 0);
+ VMA_ITERATOR(vmi, current->mm, 0);
struct vm_area_struct *vma, *prev = NULL;
vm_flags_t to_add = 0;

@@ -679,15 +678,15 @@ static int apply_mlockall_flags(int flags)
to_add |= VM_LOCKONFAULT;
}

- mas_for_each(&mas, vma, ULONG_MAX) {
+ for_each_vma(vmi, vma) {
vm_flags_t newflags;

newflags = vma->vm_flags & VM_LOCKED_CLEAR_MASK;
newflags |= to_add;

/* Ignore errors */
- mlock_fixup(vma, &prev, vma->vm_start, vma->vm_end, newflags);
- mas_pause(&mas);
+ mlock_fixup(&vmi, vma, &prev, vma->vm_start, vma->vm_end,
+ newflags);
cond_resched();
}
out:
--
2.35.1