From: "Liam R. Howlett" <Liam.Howlett@xxxxxxxxxx>
The maple tree was already tracking VMAs in this function by an earlier
commit, but the rbtree iterator was being used to iterate the list.
Change the iterator to use a maple tree native iterator and switch to the
maple tree advanced API to avoid multiple walks of the tree during insert
operations. Unexport the now-unused vma_store() function.
For performance reasons we bulk allocate the maple tree nodes. The node
calculations are done internally to the tree and use the VMA count and
assume the worst-case node requirements. The VM_DONT_COPY flag does not
allow for the most efficient copy method of the tree and so a bulk loading
algorithm is used.
Signed-off-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
---
include/linux/mm.h | 2 --
kernel/fork.c | 24 ++++++++++++++++++------
mm/mmap.c | 2 +-
3 files changed, 19 insertions(+), 9 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 2c639b0a9853..046b3d44e298 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2610,8 +2610,6 @@ extern bool arch_has_descending_max_zone_pfns(void);
/* nommu.c */
extern atomic_long_t mmap_pages_allocated;
extern int nommu_shrink_inode_mappings(struct inode *, size_t, size_t);
-/* mmap.c */
-void vma_store(struct mm_struct *mm, struct vm_area_struct *vma);
/* interval_tree.c */
void vma_interval_tree_insert(struct vm_area_struct *node,
diff --git a/kernel/fork.c b/kernel/fork.c
index c81993dff42c..6420b9500caf 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -583,7 +583,9 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm,
struct vm_area_struct *mpnt, *tmp, *prev, **pprev;
struct rb_node **rb_link, *rb_parent;
int retval;
- unsigned long charge;
+ unsigned long charge = 0;
+ MA_STATE(old_mas, &oldmm->mm_mt, 0, 0);
+ MA_STATE(mas, &mm->mm_mt, 0, 0);
LIST_HEAD(uf);
uprobe_start_dup_mmap();
@@ -617,7 +619,12 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm,
goto out;
prev = NULL;
- for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) {
+
+ retval = mas_expected_entries(&mas, oldmm->map_count);
+ if (retval)
+ goto out;
+
+ mas_for_each(&old_mas, mpnt, ULONG_MAX) {
struct file *file;
if (mpnt->vm_flags & VM_DONTCOPY) {
@@ -631,7 +638,7 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm,
*/
if (fatal_signal_pending(current)) {
retval = -EINTR;
- goto out;
+ goto loop_out;
}
if (mpnt->vm_flags & VM_ACCOUNT) {
unsigned long len = vma_pages(mpnt);
@@ -697,7 +704,9 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm,
rb_parent = &tmp->vm_rb;
/* Link the vma into the MT */
- vma_store(mm, tmp);
+ mas.index = tmp->vm_start;
+ mas.last = tmp->vm_end - 1;
+ mas_store(&mas, tmp);
mm->map_count++;
if (!(tmp->vm_flags & VM_WIPEONFORK))
@@ -707,10 +716,13 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm,
tmp->vm_ops->open(tmp);
if (retval)
- goto out;
+ goto loop_out;
+
}
/* a new mm has just been created */
retval = arch_dup_mmap(oldmm, mm);
+loop_out:
+ mas_destroy(&mas);
out:
mmap_write_unlock(mm);
flush_tlb_mm(oldmm);
@@ -726,7 +738,7 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm,
fail_nomem:
retval = -ENOMEM;
vm_unacct_memory(charge);
- goto out;
+ goto loop_out;
}
static inline int mm_alloc_pgd(struct mm_struct *mm)
diff --git a/mm/mmap.c b/mm/mmap.c
index c496814f440c..44b5e73dcfa1 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -759,7 +759,7 @@ static inline void vma_mt_szero(struct mm_struct *mm, unsigned long start,
* @mm: The struct_mm
* @vma: The vm_area_struct to store in the maple tree.
*/
-void vma_store(struct mm_struct *mm, struct vm_area_struct *vma)
+static void vma_store(struct mm_struct *mm, struct vm_area_struct *vma)
{
MA_STATE(mas, &mm->mm_mt, 0, 0);
--
2.35.1
