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mm/mmap: refactor locking out of __vma_adjust() 

Move the locking into vma_prepare() and vma_complete() for use elsewhere

Link: https://lkml.kernel.org/r/20230120162650.984577-41-Liam.Howlett@oracle.com
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Liam R. Howlett 2023-01-20 11:26:41 -05:00 committed by Andrew Morton
parent e3d73f848e
commit 440703e082
2 changed files with 150 additions and 95 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
mm/internal.h
View File

@ -941,4 +941,18 @@ static inline int vma_iter_store_gfp(struct vma_iterator *vmi,
return 0;
}
/*
* VMA lock generalization
*/
struct vma_prepare {
struct vm_area_struct *vma;
struct vm_area_struct *adj_next;
struct file *file;
struct address_space *mapping;
struct anon_vma *anon_vma;
struct vm_area_struct *insert;
struct vm_area_struct *remove;
struct vm_area_struct *remove2;
};
#endif /* __MM_INTERNAL_H */

231
mm/mmap.c
View File

@ -573,6 +573,127 @@ nomem:
return -ENOMEM;
}
/*
* vma_prepare() - Helper function for handling locking VMAs prior to altering
* @vp: The initialized vma_prepare struct
*/
static inline void vma_prepare(struct vma_prepare *vp)
{
if (vp->file) {
uprobe_munmap(vp->vma, vp->vma->vm_start, vp->vma->vm_end);
if (vp->adj_next)
uprobe_munmap(vp->adj_next, vp->adj_next->vm_start,
vp->adj_next->vm_end);
i_mmap_lock_write(vp->mapping);
if (vp->insert && vp->insert->vm_file) {
/*
* Put into interval tree now, so instantiated pages
* are visible to arm/parisc __flush_dcache_page
* throughout; but we cannot insert into address
* space until vma start or end is updated.
*/
__vma_link_file(vp->insert,
vp->insert->vm_file->f_mapping);
}
}
if (vp->anon_vma) {
anon_vma_lock_write(vp->anon_vma);
anon_vma_interval_tree_pre_update_vma(vp->vma);
if (vp->adj_next)
anon_vma_interval_tree_pre_update_vma(vp->adj_next);
}
if (vp->file) {
flush_dcache_mmap_lock(vp->mapping);
vma_interval_tree_remove(vp->vma, &vp->mapping->i_mmap);
if (vp->adj_next)
vma_interval_tree_remove(vp->adj_next,
&vp->mapping->i_mmap);
}
}
/*
* vma_complete- Helper function for handling the unlocking after altering VMAs,
* or for inserting a VMA.
*
* @vp: The vma_prepare struct
* @vmi: The vma iterator
* @mm: The mm_struct
*/
static inline void vma_complete(struct vma_prepare *vp,
struct vma_iterator *vmi, struct mm_struct *mm)
{
if (vp->file) {
if (vp->adj_next)
vma_interval_tree_insert(vp->adj_next,
&vp->mapping->i_mmap);
vma_interval_tree_insert(vp->vma, &vp->mapping->i_mmap);
flush_dcache_mmap_unlock(vp->mapping);
}
if (vp->remove && vp->file) {
__remove_shared_vm_struct(vp->remove, vp->file, vp->mapping);
if (vp->remove2)
__remove_shared_vm_struct(vp->remove2, vp->file,
vp->mapping);
} else if (vp->insert) {
/*
* split_vma has split insert from vma, and needs
* us to insert it before dropping the locks
* (it may either follow vma or precede it).
*/
vma_iter_store(vmi, vp->insert);
mm->map_count++;
}
if (vp->anon_vma) {
anon_vma_interval_tree_post_update_vma(vp->vma);
if (vp->adj_next)
anon_vma_interval_tree_post_update_vma(vp->adj_next);
anon_vma_unlock_write(vp->anon_vma);
}
if (vp->file) {
i_mmap_unlock_write(vp->mapping);
uprobe_mmap(vp->vma);
if (vp->adj_next)
uprobe_mmap(vp->adj_next);
}
if (vp->remove) {
again:
if (vp->file) {
uprobe_munmap(vp->remove, vp->remove->vm_start,
vp->remove->vm_end);
fput(vp->file);
}
if (vp->remove->anon_vma)
anon_vma_merge(vp->vma, vp->remove);
mm->map_count--;
mpol_put(vma_policy(vp->remove));
if (!vp->remove2)
WARN_ON_ONCE(vp->vma->vm_end < vp->remove->vm_end);
vm_area_free(vp->remove);
/*
* In mprotect's case 6 (see comments on vma_merge),
* we must remove next_next too.
*/
if (vp->remove2) {
vp->remove = vp->remove2;
vp->remove2 = NULL;
goto again;
}
}
if (vp->insert && vp->file)
uprobe_mmap(vp->insert);
}
/*
* We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
* is already present in an i_mmap tree without adjusting the tree.
@ -588,14 +709,13 @@ int __vma_adjust(struct vma_iterator *vmi, struct vm_area_struct *vma,
struct vm_area_struct *next_next = NULL; /* uninit var warning */
struct vm_area_struct *next = find_vma(mm, vma->vm_end);
struct vm_area_struct *orig_vma = vma;
struct address_space *mapping = NULL;
struct rb_root_cached *root = NULL;
struct anon_vma *anon_vma = NULL;
struct file *file = vma->vm_file;
bool vma_changed = false;
long adjust_next = 0;
int remove_next = 0;
struct vm_area_struct *exporter = NULL, *importer = NULL;
struct vma_prepare vma_prep;
if (next && !insert) {
if (end >= next->vm_end) {
@ -691,39 +811,22 @@ int __vma_adjust(struct vma_iterator *vmi, struct vm_area_struct *vma,
anon_vma != next->anon_vma);
vma_adjust_trans_huge(orig_vma, start, end, adjust_next);
if (file) {
mapping = file->f_mapping;
root = &mapping->i_mmap;
uprobe_munmap(vma, vma->vm_start, vma->vm_end);
if (adjust_next)
uprobe_munmap(next, next->vm_start, next->vm_end);
i_mmap_lock_write(mapping);
if (insert && insert->vm_file) {
/*
* Put into interval tree now, so instantiated pages
* are visible to arm/parisc __flush_dcache_page
* throughout; but we cannot insert into address
* space until vma start or end is updated.
*/
__vma_link_file(insert, insert->vm_file->f_mapping);
}
memset(&vma_prep, 0, sizeof(vma_prep));
vma_prep.vma = vma;
vma_prep.anon_vma = anon_vma;
vma_prep.file = file;
if (adjust_next)
vma_prep.adj_next = next;
if (file)
vma_prep.mapping = file->f_mapping;
vma_prep.insert = insert;
if (remove_next) {
vma_prep.remove = next;
vma_prep.remove2 = next_next;
}
if (anon_vma) {
anon_vma_lock_write(anon_vma);
anon_vma_interval_tree_pre_update_vma(vma);
if (adjust_next)
anon_vma_interval_tree_pre_update_vma(next);
}
if (file) {
flush_dcache_mmap_lock(mapping);
vma_interval_tree_remove(vma, root);
if (adjust_next)
vma_interval_tree_remove(next, root);
}
vma_prepare(&vma_prep);
if (start != vma->vm_start) {
if (vma->vm_start < start) {
@ -761,69 +864,7 @@ int __vma_adjust(struct vma_iterator *vmi, struct vm_area_struct *vma,
vma_iter_store(vmi, next);
}
if (file) {
if (adjust_next)
vma_interval_tree_insert(next, root);
vma_interval_tree_insert(vma, root);
flush_dcache_mmap_unlock(mapping);
}
if (remove_next && file) {
__remove_shared_vm_struct(next, file, mapping);
if (remove_next == 2)
__remove_shared_vm_struct(next_next, file, mapping);
} else if (insert) {
/*
* split_vma has split insert from vma, and needs
* us to insert it before dropping the locks
* (it may either follow vma or precede it).
*/
vma_iter_store(vmi, insert);
mm->map_count++;
}
if (anon_vma) {
anon_vma_interval_tree_post_update_vma(vma);
if (adjust_next)
anon_vma_interval_tree_post_update_vma(next);
anon_vma_unlock_write(anon_vma);
}
if (file) {
i_mmap_unlock_write(mapping);
uprobe_mmap(vma);
if (adjust_next)
uprobe_mmap(next);
}
if (remove_next) {
again:
if (file) {
uprobe_munmap(next, next->vm_start, next->vm_end);
fput(file);
}
if (next->anon_vma)
anon_vma_merge(vma, next);
mm->map_count--;
mpol_put(vma_policy(next));
if (remove_next != 2)
BUG_ON(vma->vm_end < next->vm_end);
vm_area_free(next);
/*
* In mprotect's case 6 (see comments on vma_merge),
* we must remove next_next too.
*/
if (remove_next == 2) {
remove_next = 1;
next = next_next;
goto again;
}
}
if (insert && file)
uprobe_mmap(insert);
vma_complete(&vma_prep, vmi, mm);
vma_iter_free(vmi);
validate_mm(mm);