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-rw-r--r--mm/mmap.c138
1 files changed, 97 insertions, 41 deletions
diff --git a/mm/mmap.c b/mm/mmap.c
index 31656147128..6a0c15db7f6 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -437,7 +437,6 @@ __vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
{
__vma_link_list(mm, vma, prev, rb_parent);
__vma_link_rb(mm, vma, rb_link, rb_parent);
- __anon_vma_link(vma);
}
static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
@@ -499,7 +498,7 @@ __vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma,
* are necessary. The "insert" vma (if any) is to be inserted
* before we drop the necessary locks.
*/
-void vma_adjust(struct vm_area_struct *vma, unsigned long start,
+int vma_adjust(struct vm_area_struct *vma, unsigned long start,
unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert)
{
struct mm_struct *mm = vma->vm_mm;
@@ -542,6 +541,28 @@ again: remove_next = 1 + (end > next->vm_end);
}
}
+ /*
+ * When changing only vma->vm_end, we don't really need anon_vma lock.
+ */
+ if (vma->anon_vma && (insert || importer || start != vma->vm_start))
+ anon_vma = vma->anon_vma;
+ if (anon_vma) {
+ /*
+ * Easily overlooked: when mprotect shifts the boundary,
+ * make sure the expanding vma has anon_vma set if the
+ * shrinking vma had, to cover any anon pages imported.
+ */
+ if (importer && !importer->anon_vma) {
+ /* Block reverse map lookups until things are set up. */
+ importer->vm_flags |= VM_LOCK_RMAP;
+ if (anon_vma_clone(importer, vma)) {
+ importer->vm_flags &= ~VM_LOCK_RMAP;
+ return -ENOMEM;
+ }
+ importer->anon_vma = anon_vma;
+ }
+ }
+
if (file) {
mapping = file->f_mapping;
if (!(vma->vm_flags & VM_NONLINEAR))
@@ -567,25 +588,6 @@ again: remove_next = 1 + (end > next->vm_end);
}
}
- /*
- * When changing only vma->vm_end, we don't really need
- * anon_vma lock.
- */
- if (vma->anon_vma && (insert || importer || start != vma->vm_start))
- anon_vma = vma->anon_vma;
- if (anon_vma) {
- spin_lock(&anon_vma->lock);
- /*
- * Easily overlooked: when mprotect shifts the boundary,
- * make sure the expanding vma has anon_vma set if the
- * shrinking vma had, to cover any anon pages imported.
- */
- if (importer && !importer->anon_vma) {
- importer->anon_vma = anon_vma;
- __anon_vma_link(importer);
- }
- }
-
if (root) {
flush_dcache_mmap_lock(mapping);
vma_prio_tree_remove(vma, root);
@@ -616,8 +618,11 @@ again: remove_next = 1 + (end > next->vm_end);
__vma_unlink(mm, next, vma);
if (file)
__remove_shared_vm_struct(next, file, mapping);
- if (next->anon_vma)
- __anon_vma_merge(vma, next);
+ /*
+ * This VMA is now dead, no need for rmap to follow it.
+ * Call anon_vma_merge below, outside of i_mmap_lock.
+ */
+ next->vm_flags |= VM_LOCK_RMAP;
} else if (insert) {
/*
* split_vma has split insert from vma, and needs
@@ -627,17 +632,25 @@ again: remove_next = 1 + (end > next->vm_end);
__insert_vm_struct(mm, insert);
}
- if (anon_vma)
- spin_unlock(&anon_vma->lock);
if (mapping)
spin_unlock(&mapping->i_mmap_lock);
+ /*
+ * The current VMA has been set up. It is now safe for the
+ * rmap code to get from the pages to the ptes.
+ */
+ if (anon_vma && importer)
+ importer->vm_flags &= ~VM_LOCK_RMAP;
+
if (remove_next) {
if (file) {
fput(file);
if (next->vm_flags & VM_EXECUTABLE)
removed_exe_file_vma(mm);
}
+ /* Protected by mmap_sem and VM_LOCK_RMAP. */
+ if (next->anon_vma)
+ anon_vma_merge(vma, next);
mm->map_count--;
mpol_put(vma_policy(next));
kmem_cache_free(vm_area_cachep, next);
@@ -653,6 +666,8 @@ again: remove_next = 1 + (end > next->vm_end);
}
validate_mm(mm);
+
+ return 0;
}
/*
@@ -759,6 +774,7 @@ struct vm_area_struct *vma_merge(struct mm_struct *mm,
{
pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
struct vm_area_struct *area, *next;
+ int err;
/*
* We later require that vma->vm_flags == vm_flags,
@@ -792,11 +808,13 @@ struct vm_area_struct *vma_merge(struct mm_struct *mm,
is_mergeable_anon_vma(prev->anon_vma,
next->anon_vma)) {
/* cases 1, 6 */
- vma_adjust(prev, prev->vm_start,
+ err = vma_adjust(prev, prev->vm_start,
next->vm_end, prev->vm_pgoff, NULL);
} else /* cases 2, 5, 7 */
- vma_adjust(prev, prev->vm_start,
+ err = vma_adjust(prev, prev->vm_start,
end, prev->vm_pgoff, NULL);
+ if (err)
+ return NULL;
return prev;
}
@@ -808,11 +826,13 @@ struct vm_area_struct *vma_merge(struct mm_struct *mm,
can_vma_merge_before(next, vm_flags,
anon_vma, file, pgoff+pglen)) {
if (prev && addr < prev->vm_end) /* case 4 */
- vma_adjust(prev, prev->vm_start,
+ err = vma_adjust(prev, prev->vm_start,
addr, prev->vm_pgoff, NULL);
else /* cases 3, 8 */
- vma_adjust(area, addr, next->vm_end,
+ err = vma_adjust(area, addr, next->vm_end,
next->vm_pgoff - pglen, NULL);
+ if (err)
+ return NULL;
return area;
}
@@ -1205,6 +1225,7 @@ munmap_back:
vma->vm_flags = vm_flags;
vma->vm_page_prot = vm_get_page_prot(vm_flags);
vma->vm_pgoff = pgoff;
+ INIT_LIST_HEAD(&vma->anon_vma_chain);
if (file) {
error = -EINVAL;
@@ -1865,6 +1886,7 @@ static int __split_vma(struct mm_struct * mm, struct vm_area_struct * vma,
{
struct mempolicy *pol;
struct vm_area_struct *new;
+ int err = -ENOMEM;
if (is_vm_hugetlb_page(vma) && (addr &
~(huge_page_mask(hstate_vma(vma)))))
@@ -1872,11 +1894,13 @@ static int __split_vma(struct mm_struct * mm, struct vm_area_struct * vma,
new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
if (!new)
- return -ENOMEM;
+ goto out_err;
/* most fields are the same, copy all, and then fixup */
*new = *vma;
+ INIT_LIST_HEAD(&new->anon_vma_chain);
+
if (new_below)
new->vm_end = addr;
else {
@@ -1886,11 +1910,14 @@ static int __split_vma(struct mm_struct * mm, struct vm_area_struct * vma,
pol = mpol_dup(vma_policy(vma));
if (IS_ERR(pol)) {
- kmem_cache_free(vm_area_cachep, new);
- return PTR_ERR(pol);
+ err = PTR_ERR(pol);
+ goto out_free_vma;
}
vma_set_policy(new, pol);
+ if (anon_vma_clone(new, vma))
+ goto out_free_mpol;
+
if (new->vm_file) {
get_file(new->vm_file);
if (vma->vm_flags & VM_EXECUTABLE)
@@ -1901,12 +1928,28 @@ static int __split_vma(struct mm_struct * mm, struct vm_area_struct * vma,
new->vm_ops->open(new);
if (new_below)
- vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
+ err = vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
((addr - new->vm_start) >> PAGE_SHIFT), new);
else
- vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
+ err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
- return 0;
+ /* Success. */
+ if (!err)
+ return 0;
+
+ /* Clean everything up if vma_adjust failed. */
+ new->vm_ops->close(new);
+ if (new->vm_file) {
+ if (vma->vm_flags & VM_EXECUTABLE)
+ removed_exe_file_vma(mm);
+ fput(new->vm_file);
+ }
+ out_free_mpol:
+ mpol_put(pol);
+ out_free_vma:
+ kmem_cache_free(vm_area_cachep, new);
+ out_err:
+ return err;
}
/*
@@ -2116,6 +2159,7 @@ unsigned long do_brk(unsigned long addr, unsigned long len)
return -ENOMEM;
}
+ INIT_LIST_HEAD(&vma->anon_vma_chain);
vma->vm_mm = mm;
vma->vm_start = addr;
vma->vm_end = addr + len;
@@ -2252,10 +2296,11 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
if (new_vma) {
*new_vma = *vma;
pol = mpol_dup(vma_policy(vma));
- if (IS_ERR(pol)) {
- kmem_cache_free(vm_area_cachep, new_vma);
- return NULL;
- }
+ if (IS_ERR(pol))
+ goto out_free_vma;
+ INIT_LIST_HEAD(&new_vma->anon_vma_chain);
+ if (anon_vma_clone(new_vma, vma))
+ goto out_free_mempol;
vma_set_policy(new_vma, pol);
new_vma->vm_start = addr;
new_vma->vm_end = addr + len;
@@ -2271,6 +2316,12 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
}
}
return new_vma;
+
+ out_free_mempol:
+ mpol_put(pol);
+ out_free_vma:
+ kmem_cache_free(vm_area_cachep, new_vma);
+ return NULL;
}
/*
@@ -2348,6 +2399,7 @@ int install_special_mapping(struct mm_struct *mm,
if (unlikely(vma == NULL))
return -ENOMEM;
+ INIT_LIST_HEAD(&vma->anon_vma_chain);
vma->vm_mm = mm;
vma->vm_start = addr;
vma->vm_end = addr + len;
@@ -2448,6 +2500,7 @@ static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
int mm_take_all_locks(struct mm_struct *mm)
{
struct vm_area_struct *vma;
+ struct anon_vma_chain *avc;
int ret = -EINTR;
BUG_ON(down_read_trylock(&mm->mmap_sem));
@@ -2465,7 +2518,8 @@ int mm_take_all_locks(struct mm_struct *mm)
if (signal_pending(current))
goto out_unlock;
if (vma->anon_vma)
- vm_lock_anon_vma(mm, vma->anon_vma);
+ list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
+ vm_lock_anon_vma(mm, avc->anon_vma);
}
ret = 0;
@@ -2520,13 +2574,15 @@ static void vm_unlock_mapping(struct address_space *mapping)
void mm_drop_all_locks(struct mm_struct *mm)
{
struct vm_area_struct *vma;
+ struct anon_vma_chain *avc;
BUG_ON(down_read_trylock(&mm->mmap_sem));
BUG_ON(!mutex_is_locked(&mm_all_locks_mutex));
for (vma = mm->mmap; vma; vma = vma->vm_next) {
if (vma->anon_vma)
- vm_unlock_anon_vma(vma->anon_vma);
+ list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
+ vm_unlock_anon_vma(avc->anon_vma);
if (vma->vm_file && vma->vm_file->f_mapping)
vm_unlock_mapping(vma->vm_file->f_mapping);
}
generated by cgit v1.2.3-70-g09d2 (git 2.46.0) at 2024-11-16 23:05:30 +0000