diff options
Diffstat (limited to 'mm/mmap.c')
| -rw-r--r-- | mm/mmap.c | 30 |
1 files changed, 24 insertions, 6 deletions
diff --git a/mm/mmap.c b/mm/mmap.c index 64c9d736155c..c1f2ea4a0b99 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -221,7 +221,7 @@ static void __remove_shared_vm_struct(struct vm_area_struct *vma, if (vma->vm_flags & VM_DENYWRITE) atomic_inc(&file_inode(file)->i_writecount); if (vma->vm_flags & VM_SHARED) - mapping->i_mmap_writable--; + mapping_unmap_writable(mapping); flush_dcache_mmap_lock(mapping); if (unlikely(vma->vm_flags & VM_NONLINEAR)) @@ -622,7 +622,7 @@ static void __vma_link_file(struct vm_area_struct *vma) if (vma->vm_flags & VM_DENYWRITE) atomic_dec(&file_inode(file)->i_writecount); if (vma->vm_flags & VM_SHARED) - mapping->i_mmap_writable++; + atomic_inc(&mapping->i_mmap_writable); flush_dcache_mmap_lock(mapping); if (unlikely(vma->vm_flags & VM_NONLINEAR)) @@ -1577,6 +1577,17 @@ munmap_back: if (error) goto free_vma; } + if (vm_flags & VM_SHARED) { + error = mapping_map_writable(file->f_mapping); + if (error) + goto allow_write_and_free_vma; + } + + /* ->mmap() can change vma->vm_file, but must guarantee that + * vma_link() below can deny write-access if VM_DENYWRITE is set + * and map writably if VM_SHARED is set. This usually means the + * new file must not have been exposed to user-space, yet. + */ vma->vm_file = get_file(file); error = file->f_op->mmap(file, vma); if (error) @@ -1616,8 +1627,12 @@ munmap_back: vma_link(mm, vma, prev, rb_link, rb_parent); /* Once vma denies write, undo our temporary denial count */ - if (vm_flags & VM_DENYWRITE) - allow_write_access(file); + if (file) { + if (vm_flags & VM_SHARED) + mapping_unmap_writable(file->f_mapping); + if (vm_flags & VM_DENYWRITE) + allow_write_access(file); + } file = vma->vm_file; out: perf_event_mmap(vma); @@ -1646,14 +1661,17 @@ out: return addr; unmap_and_free_vma: - if (vm_flags & VM_DENYWRITE) - allow_write_access(file); vma->vm_file = NULL; fput(file); /* Undo any partial mapping done by a device driver. */ unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end); charged = 0; + if (vm_flags & VM_SHARED) + mapping_unmap_writable(file->f_mapping); +allow_write_and_free_vma: + if (vm_flags & VM_DENYWRITE) + allow_write_access(file); free_vma: kmem_cache_free(vm_area_cachep, vma); unacct_error: |