mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-10-31 16:38:12 +00:00
[PATCH] mm: unlink_file_vma, remove_vma
Divide remove_vm_struct into two parts: first anon_vma_unlink plus unlink_file_vma, to unlink the vma from the list and tree by which rmap or vmtruncate might find it; then remove_vma to close, fput and free. The intention here is to do the anon_vma_unlink and unlink_file_vma earlier, in free_pgtables before freeing any page tables: so we can be sure that any page tables traversed by rmap and vmtruncate are stable (and other, ordinary cases are stabilized by holding mmap_sem). This will be crucial to traversing pgd,pud,pmd without page_table_lock. But testing the split-out patch showed that lifting the page_table_lock is symbiotically necessary to make this change - the lock ordering is wrong to move those unlinks into free_pgtables while it's under ptlock. Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
parent
2c0b381467
commit
a8fb5618da
2 changed files with 28 additions and 14 deletions
|
@ -834,6 +834,7 @@ extern int split_vma(struct mm_struct *,
|
|||
extern int insert_vm_struct(struct mm_struct *, struct vm_area_struct *);
|
||||
extern void __vma_link_rb(struct mm_struct *, struct vm_area_struct *,
|
||||
struct rb_node **, struct rb_node *);
|
||||
extern void unlink_file_vma(struct vm_area_struct *);
|
||||
extern struct vm_area_struct *copy_vma(struct vm_area_struct **,
|
||||
unsigned long addr, unsigned long len, pgoff_t pgoff);
|
||||
extern void exit_mmap(struct mm_struct *);
|
||||
|
|
41
mm/mmap.c
41
mm/mmap.c
|
@ -181,26 +181,44 @@ static void __remove_shared_vm_struct(struct vm_area_struct *vma,
|
|||
}
|
||||
|
||||
/*
|
||||
* Remove one vm structure and free it.
|
||||
* Unlink a file-based vm structure from its prio_tree, to hide
|
||||
* vma from rmap and vmtruncate before freeing its page tables.
|
||||
*/
|
||||
static void remove_vm_struct(struct vm_area_struct *vma)
|
||||
void unlink_file_vma(struct vm_area_struct *vma)
|
||||
{
|
||||
struct file *file = vma->vm_file;
|
||||
|
||||
might_sleep();
|
||||
if (file) {
|
||||
struct address_space *mapping = file->f_mapping;
|
||||
spin_lock(&mapping->i_mmap_lock);
|
||||
__remove_shared_vm_struct(vma, file, mapping);
|
||||
spin_unlock(&mapping->i_mmap_lock);
|
||||
}
|
||||
}
|
||||
|
||||
/*
|
||||
* Close a vm structure and free it, returning the next.
|
||||
*/
|
||||
static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
|
||||
{
|
||||
struct vm_area_struct *next = vma->vm_next;
|
||||
|
||||
/*
|
||||
* Hide vma from rmap and vmtruncate before freeing page tables:
|
||||
* to be moved into free_pgtables once page_table_lock is lifted
|
||||
* from it, but until then lock ordering forbids that move.
|
||||
*/
|
||||
anon_vma_unlink(vma);
|
||||
unlink_file_vma(vma);
|
||||
|
||||
might_sleep();
|
||||
if (vma->vm_ops && vma->vm_ops->close)
|
||||
vma->vm_ops->close(vma);
|
||||
if (file)
|
||||
fput(file);
|
||||
anon_vma_unlink(vma);
|
||||
if (vma->vm_file)
|
||||
fput(vma->vm_file);
|
||||
mpol_free(vma_policy(vma));
|
||||
kmem_cache_free(vm_area_cachep, vma);
|
||||
return next;
|
||||
}
|
||||
|
||||
asmlinkage unsigned long sys_brk(unsigned long brk)
|
||||
|
@ -1612,15 +1630,13 @@ find_extend_vma(struct mm_struct * mm, unsigned long addr)
|
|||
static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
|
||||
{
|
||||
do {
|
||||
struct vm_area_struct *next = vma->vm_next;
|
||||
long nrpages = vma_pages(vma);
|
||||
|
||||
mm->total_vm -= nrpages;
|
||||
if (vma->vm_flags & VM_LOCKED)
|
||||
mm->locked_vm -= nrpages;
|
||||
vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages);
|
||||
remove_vm_struct(vma);
|
||||
vma = next;
|
||||
vma = remove_vma(vma);
|
||||
} while (vma);
|
||||
validate_mm(mm);
|
||||
}
|
||||
|
@ -1944,11 +1960,8 @@ void exit_mmap(struct mm_struct *mm)
|
|||
* Walk the list again, actually closing and freeing it
|
||||
* without holding any MM locks.
|
||||
*/
|
||||
while (vma) {
|
||||
struct vm_area_struct *next = vma->vm_next;
|
||||
remove_vm_struct(vma);
|
||||
vma = next;
|
||||
}
|
||||
while (vma)
|
||||
vma = remove_vma(vma);
|
||||
|
||||
BUG_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT);
|
||||
}
|
||||
|
|
Loading…
Reference in a new issue