[PATCH v4 43/49] mm: Don't use __vma_adjust() in __split_vma()

From: Liam R. Howlett
Date: Fri Jan 20 2023 - 11:41:39 EST

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From: "Liam R. Howlett" <Liam.Howlett@xxxxxxxxxx>

Use the abstracted locking and maple tree operations. Since
__split_vma() is the only user of the __vma_adjust() function to use the
insert argument, drop that argument. Remove the NULL passed through
from fs/exec's shift_arg_pages() and mremap() at the same time.

Signed-off-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
---
fs/exec.c | 4 +-
include/linux/mm.h | 7 ++-
mm/mmap.c | 118 +++++++++++++++++++++------------------------
mm/mremap.c | 2 +-
4 files changed, 61 insertions(+), 70 deletions(-)

diff --git a/fs/exec.c b/fs/exec.c
index 76ee62e1d3f1..d52fca2dd30b 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -699,7 +699,7 @@ static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
/*
* cover the whole range: [new_start, old_end)
*/
- if (vma_adjust(&vmi, vma, new_start, old_end, vma->vm_pgoff, NULL))
+ if (vma_adjust(&vmi, vma, new_start, old_end, vma->vm_pgoff))
return -ENOMEM;

/*
@@ -733,7 +733,7 @@ static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)

vma_prev(&vmi);
/* Shrink the vma to just the new range */
- return vma_adjust(&vmi, vma, new_start, new_end, vma->vm_pgoff, NULL);
+ return vma_adjust(&vmi, vma, new_start, new_end, vma->vm_pgoff);
}

/*
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 75b6d06d69d5..c372c09e11b5 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2832,13 +2832,12 @@ void anon_vma_interval_tree_verify(struct anon_vma_chain *node);
/* mmap.c */
extern int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin);
extern int __vma_adjust(struct vma_iterator *vmi, struct vm_area_struct *vma, unsigned long start,
- unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert,
- struct vm_area_struct *expand);
+ unsigned long end, pgoff_t pgoff, struct vm_area_struct *expand);
static inline int vma_adjust(struct vma_iterator *vmi,
struct vm_area_struct *vma, unsigned long start, unsigned long end,
- pgoff_t pgoff, struct vm_area_struct *insert)
+ pgoff_t pgoff)
{
- return __vma_adjust(vmi, vma, start, end, pgoff, insert, NULL);
+ return __vma_adjust(vmi, vma, start, end, pgoff, NULL);
}
extern struct vm_area_struct *vma_merge(struct vma_iterator *vmi,
struct mm_struct *, struct vm_area_struct *prev, unsigned long addr,
diff --git a/mm/mmap.c b/mm/mmap.c
index 7eb93c311d8d..c1eb353c16f8 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -694,7 +694,7 @@ inline int vma_expand(struct vma_iterator *vmi, struct vm_area_struct *vma,
*/
int __vma_adjust(struct vma_iterator *vmi, struct vm_area_struct *vma,
unsigned long start, unsigned long end, pgoff_t pgoff,
- struct vm_area_struct *insert, struct vm_area_struct *expand)
+ struct vm_area_struct *expand)
{
struct mm_struct *mm = vma->vm_mm;
struct vm_area_struct *remove2 = NULL;
@@ -707,7 +707,7 @@ int __vma_adjust(struct vma_iterator *vmi, struct vm_area_struct *vma,
struct vm_area_struct *exporter = NULL, *importer = NULL;
struct vma_prepare vma_prep;

- if (next && !insert) {
+ if (next) {
if (end >= next->vm_end) {
/*
* vma expands, overlapping all the next, and
@@ -798,39 +798,25 @@ int __vma_adjust(struct vma_iterator *vmi, struct vm_area_struct *vma,
VM_WARN_ON(vma_prep.anon_vma && adjust_next && next->anon_vma &&
vma_prep.anon_vma != next->anon_vma);

- vma_prep.insert = insert;
vma_prepare(&vma_prep);

- if (start != vma->vm_start) {
- if (vma->vm_start < start) {
- if (!insert || (insert->vm_end != start)) {
- vma_iter_clear(vmi, vma->vm_start, start);
- vma_iter_set(vmi, start);
- VM_WARN_ON(insert && insert->vm_start > vma->vm_start);
- }
- } else {
- vma_changed = true;
- }
- vma->vm_start = start;
- }
- if (end != vma->vm_end) {
- if (vma->vm_end > end) {
- if (!insert || (insert->vm_start != end)) {
- vma_iter_clear(vmi, end, vma->vm_end);
- vma_iter_set(vmi, vma->vm_end);
- VM_WARN_ON(insert &&
- insert->vm_end < vma->vm_end);
- }
- } else {
- vma_changed = true;
- }
- vma->vm_end = end;
- }
+ if (vma->vm_start < start)
+ vma_iter_clear(vmi, vma->vm_start, start);
+ else if (start != vma->vm_start)
+ vma_changed = true;
+
+ if (vma->vm_end > end)
+ vma_iter_clear(vmi, end, vma->vm_end);
+ else if (end != vma->vm_end)
+ vma_changed = true;
+
+ vma->vm_start = start;
+ vma->vm_end = end;
+ vma->vm_pgoff = pgoff;

if (vma_changed)
vma_iter_store(vmi, vma);

- vma->vm_pgoff = pgoff;
if (adjust_next) {
next->vm_start += adjust_next;
next->vm_pgoff += adjust_next >> PAGE_SHIFT;
@@ -849,9 +835,9 @@ int __vma_adjust(struct vma_iterator *vmi, struct vm_area_struct *vma,
* per-vma resources, so we don't attempt to merge those.
*/
static inline int is_mergeable_vma(struct vm_area_struct *vma,
- struct file *file, unsigned long vm_flags,
- struct vm_userfaultfd_ctx vm_userfaultfd_ctx,
- struct anon_vma_name *anon_name)
+ struct file *file, unsigned long vm_flags,
+ struct vm_userfaultfd_ctx vm_userfaultfd_ctx,
+ struct anon_vma_name *anon_name)
{
/*
* VM_SOFTDIRTY should not prevent from VMA merging, if we
@@ -1033,20 +1019,19 @@ struct vm_area_struct *vma_merge(struct vma_iterator *vmi, struct mm_struct *mm,
is_mergeable_anon_vma(prev->anon_vma,
next->anon_vma, NULL)) { /* cases 1, 6 */
err = __vma_adjust(vmi, prev, prev->vm_start,
- next->vm_end, prev->vm_pgoff, NULL,
- prev);
+ next->vm_end, prev->vm_pgoff, prev);
res = prev;
} else if (merge_prev) { /* cases 2, 5, 7 */
err = __vma_adjust(vmi, prev, prev->vm_start,
- end, prev->vm_pgoff, NULL, prev);
+ end, prev->vm_pgoff, prev);
res = prev;
} else if (merge_next) {
if (prev && addr < prev->vm_end) /* case 4 */
err = __vma_adjust(vmi, prev, prev->vm_start,
- addr, prev->vm_pgoff, NULL, next);
+ addr, prev->vm_pgoff, next);
else /* cases 3, 8 */
err = __vma_adjust(vmi, mid, addr, next->vm_end,
- next->vm_pgoff - pglen, NULL, next);
+ next->vm_pgoff - pglen, next);
res = next;
}

@@ -2190,11 +2175,15 @@ static void unmap_region(struct mm_struct *mm, struct maple_tree *mt,
int __split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma,
unsigned long addr, int new_below)
{
+ struct vma_prepare vp;
struct vm_area_struct *new;
int err;

validate_mm_mt(vma->vm_mm);

+ WARN_ON(vma->vm_start >= addr);
+ WARN_ON(vma->vm_end <= addr);
+
if (vma->vm_ops && vma->vm_ops->may_split) {
err = vma->vm_ops->may_split(vma, addr);
if (err)
@@ -2205,16 +2194,20 @@ int __split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma,
if (!new)
return -ENOMEM;

- if (new_below)
+ err = -ENOMEM;
+ if (vma_iter_prealloc(vmi))
+ goto out_free_vma;
+
+ if (new_below) {
new->vm_end = addr;
- else {
+ } else {
new->vm_start = addr;
new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
}

err = vma_dup_policy(vma, new);
if (err)
- goto out_free_vma;
+ goto out_free_vmi;

err = anon_vma_clone(new, vma);
if (err)
@@ -2226,33 +2219,32 @@ int __split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma,
if (new->vm_ops && new->vm_ops->open)
new->vm_ops->open(new);

- if (new_below)
- err = vma_adjust(vmi, vma, addr, vma->vm_end,
- vma->vm_pgoff + ((addr - new->vm_start) >> PAGE_SHIFT),
- new);
- else
- err = vma_adjust(vmi, vma, vma->vm_start, addr, vma->vm_pgoff,
- new);
+ vma_adjust_trans_huge(vma, vma->vm_start, addr, 0);
+ init_vma_prep(&vp, vma);
+ vp.insert = new;
+ vma_prepare(&vp);

- /* Success. */
- if (!err) {
- if (new_below)
- vma_next(vmi);
- return 0;
+ if (new_below) {
+ vma->vm_start = addr;
+ vma->vm_pgoff += (addr - new->vm_start) >> PAGE_SHIFT;
+ } else {
+ vma->vm_end = addr;
}

- /* Avoid vm accounting in close() operation */
- new->vm_start = new->vm_end;
- new->vm_pgoff = 0;
- /* Clean everything up if vma_adjust failed. */
- if (new->vm_ops && new->vm_ops->close)
- new->vm_ops->close(new);
- if (new->vm_file)
- fput(new->vm_file);
- unlink_anon_vmas(new);
- out_free_mpol:
+ /* vma_complete stores the new vma */
+ vma_complete(&vp, vmi, vma->vm_mm);
+
+ /* Success. */
+ if (new_below)
+ vma_next(vmi);
+ validate_mm_mt(vma->vm_mm);
+ return 0;
+
+out_free_mpol:
mpol_put(vma_policy(new));
- out_free_vma:
+out_free_vmi:
+ vma_iter_free(vmi);
+out_free_vma:
vm_area_free(new);
validate_mm_mt(vma->vm_mm);
return err;
diff --git a/mm/mremap.c b/mm/mremap.c
index 1bc81afd90de..30eea37f9fc4 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -1053,7 +1053,7 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
vma->vm_file, extension_pgoff, vma_policy(vma),
vma->vm_userfaultfd_ctx, anon_vma_name(vma));
} else if (vma_adjust(&vmi, vma, vma->vm_start,
- addr + new_len, vma->vm_pgoff, NULL)) {
+ addr + new_len, vma->vm_pgoff)) {
vma = NULL;
}
if (!vma) {
--
2.35.1

Next message: Alexander Shishkin: "Re: [PATCH v1 4/6] virtio console: Harden control message handling"
Previous message: Phil Auld: "[PATCH v2] sched/debug: Put sched/domains files under the verbose flag"
In reply to: Liam R. Howlett: "[PATCH v4 48/49] mm/mmap: Remove __vma_adjust()"
Next in thread: Liam R. Howlett: "[PATCH v4 16/49] userfaultfd: Use vma iterator"
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