sys_remap_file_pages: fix ->vm_file accounting

Fix ->vm_file accounting, mmap_region() may do do_munmap().

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 1 deletions

diff --git a/mm/fremap.c b/mm/fremap.c
index 14bd3bf7826..69a37c2bdf8 100644
--- a/mm/fremap.c
+++ b/mm/fremap.c
@@ -190,10 +190,13 @@ asmlinkage long sys_remap_file_pages(unsigned long start, unsigned long size,
                  */
                 if (mapping_cap_account_dirty(mapping)) {
                         unsigned long addr;
+                        struct file *file = vma->vm_file;
 
                         flags &= MAP_NONBLOCK;
-                        addr = mmap_region(vma->vm_file, start, size,
+                        get_file(file);
+                        addr = mmap_region(file, start, size,
                                         flags, vma->vm_flags, pgoff, 1);
+                        fput(file);
                         if (IS_ERR_VALUE(addr)) {
                                 err = addr;
                         } else {