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NOMMU: Lock i_mmap_mutex for access to the VMA prio list

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Lock i_mmap_mutex for access to the VMA prio list to prevent concurrent
access.  Currently, certain parts of the mmap handling are protected by
the region mutex, but not all.

Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
David Howells 2012-02-23 13:50:35 +00:00 committed by Linus Torvalds
parent 37e79cbf7d
commit 918e556ec2
1 changed files with 7 additions and 0 deletions
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7
mm/nommu.c
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@ -696,9 +696,11 @@ static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma)
if (vma->vm_file) {
mapping = vma->vm_file->f_mapping;
mutex_lock(&mapping->i_mmap_mutex);
flush_dcache_mmap_lock(mapping);
vma_prio_tree_insert(vma, &mapping->i_mmap);
flush_dcache_mmap_unlock(mapping);
mutex_unlock(&mapping->i_mmap_mutex);
}
/* add the VMA to the tree */
@ -760,9 +762,11 @@ static void delete_vma_from_mm(struct vm_area_struct *vma)
if (vma->vm_file) {
mapping = vma->vm_file->f_mapping;
mutex_lock(&mapping->i_mmap_mutex);
flush_dcache_mmap_lock(mapping);
vma_prio_tree_remove(vma, &mapping->i_mmap);
flush_dcache_mmap_unlock(mapping);
mutex_unlock(&mapping->i_mmap_mutex);
}
/* remove from the MM's tree and list */
@ -2052,6 +2056,7 @@ int nommu_shrink_inode_mappings(struct inode *inode, size_t size,
high = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
down_write(&nommu_region_sem);
mutex_lock(&inode->i_mapping->i_mmap_mutex);
/* search for VMAs that fall within the dead zone */
vma_prio_tree_foreach(vma, &iter, &inode->i_mapping->i_mmap,
@ -2059,6 +2064,7 @@ int nommu_shrink_inode_mappings(struct inode *inode, size_t size,
/* found one - only interested if it's shared out of the page
* cache */
if (vma->vm_flags & VM_SHARED) {
mutex_unlock(&inode->i_mapping->i_mmap_mutex);
up_write(&nommu_region_sem);
return -ETXTBSY; /* not quite true, but near enough */
}
@ -2086,6 +2092,7 @@ int nommu_shrink_inode_mappings(struct inode *inode, size_t size,
}
}
mutex_unlock(&inode->i_mapping->i_mmap_mutex);
up_write(&nommu_region_sem);
return 0;
}