fix mremap() vs. ioctx_kill() race
teach ->mremap() method to return an error and have it fail for
aio mappings in process of being killed
Note that in case of ->mremap() failure we need to undo move_page_tables()
we'd already done; we could call ->mremap() first, but then the failure of
move_page_tables() would require undoing whatever _successful_ ->mremap()
has done, which would be a lot more headache in general.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/mm/mremap.c b/mm/mremap.c
index 57dadc0..2dc44b1 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -286,8 +286,14 @@
old_len = new_len;
old_addr = new_addr;
new_addr = -ENOMEM;
- } else if (vma->vm_file && vma->vm_file->f_op->mremap)
- vma->vm_file->f_op->mremap(vma->vm_file, new_vma);
+ } else if (vma->vm_file && vma->vm_file->f_op->mremap) {
+ err = vma->vm_file->f_op->mremap(vma->vm_file, new_vma);
+ if (err < 0) {
+ move_page_tables(new_vma, new_addr, vma, old_addr,
+ moved_len, true);
+ return err;
+ }
+ }
/* Conceal VM_ACCOUNT so old reservation is not undone */
if (vm_flags & VM_ACCOUNT) {