diff options
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/madvise.c | 16 |
1 files changed, 13 insertions, 3 deletions
diff --git a/mm/madvise.c b/mm/madvise.c index 319528b8db7..83aa92aad8b 100644 --- a/mm/madvise.c +++ b/mm/madvise.c @@ -13,6 +13,7 @@ #include <linux/hugetlb.h> #include <linux/sched.h> #include <linux/ksm.h> +#include <linux/file.h> /* * Any behaviour which results in changes to the vma->vm_flags needs to @@ -191,14 +192,16 @@ static long madvise_remove(struct vm_area_struct *vma, struct address_space *mapping; loff_t offset, endoff; int error; + struct file *f; *prev = NULL; /* tell sys_madvise we drop mmap_sem */ if (vma->vm_flags & (VM_LOCKED|VM_NONLINEAR|VM_HUGETLB)) return -EINVAL; - if (!vma->vm_file || !vma->vm_file->f_mapping - || !vma->vm_file->f_mapping->host) { + f = vma->vm_file; + + if (!f || !f->f_mapping || !f->f_mapping->host) { return -EINVAL; } @@ -212,9 +215,16 @@ static long madvise_remove(struct vm_area_struct *vma, endoff = (loff_t)(end - vma->vm_start - 1) + ((loff_t)vma->vm_pgoff << PAGE_SHIFT); - /* vmtruncate_range needs to take i_mutex and i_alloc_sem */ + /* + * vmtruncate_range may need to take i_mutex and i_alloc_sem. + * We need to explicitly grab a reference because the vma (and + * hence the vma's reference to the file) can go away as soon as + * we drop mmap_sem. + */ + get_file(f); up_read(¤t->mm->mmap_sem); error = vmtruncate_range(mapping->host, offset, endoff); + fput(f); down_read(¤t->mm->mmap_sem); return error; } |