This hook was introduced to work around code that seemed to absolutely require access to a VMA pointer upon mmap(). However, providing this hook leaves a backdoor to drivers getting access to the very thing mmap_prepare eliminates - a pointer to the VMA. Let's solve this contradiction by removing it. The key intended user was hugetlb, however it seems that the best course now is to avoid allowing all drivers the ability to work around mmap_prepare, and find a different solution there.
Unified · Split
| @@ -843,16 +843,6 @@ struct mmap_action { · 842 unmodified lines | |||
| 843 | }; | 843 | }; |
| 844 | enum mmap_action_type type; | 844 | enum mmap_action_type type; |
| 845 | 845 | ||
| 846 | /* | ||
| 847 | * If specified, this hook is invoked after the selected action has been | ||
| 848 | * successfully completed. Note that the VMA write lock still held. | ||
| 849 | * | ||
| 850 | * The absolute minimum ought to be done here. | ||
| 851 | * | ||
| 852 | * Returns 0 on success, or an error code. | ||
| 853 | */ | ||
| 854 | int (*success_hook)(const struct vm_area_struct *vma); | ||
| 855 | |||
| 856 | /* | 846 | /* |
| 857 | * If specified, this hook is invoked when an error occurred when | 847 | * If specified, this hook is invoked when an error occurred when |
| 858 | * attempting the selected action. | 848 | * attempting the selected action. |
| @@ -1397,8 +1397,6 @@ static int mmap_action_finish(struct vm_area_struct *vma, · 1396 unmodified lines | |||
| 1397 | 1397 | ||
| 1398 | if (!err) | 1398 | if (!err) |
| 1399 | err = call_vma_mapped(vma); | 1399 | err = call_vma_mapped(vma); |
| 1400 | if (!err && action->success_hook) | ||
| 1401 | err = action->success_hook(vma); | ||
| 1402 | 1400 | ||
| 1403 | /* do_munmap() might take rmap lock, so release if held. */ | 1401 | /* do_munmap() might take rmap lock, so release if held. */ |
| 1404 | maybe_rmap_unlock_action(vma, action); | 1402 | maybe_rmap_unlock_action(vma, action); |
| @@ -482,16 +482,6 @@ struct mmap_action { · 481 unmodified lines | |||
| 482 | }; | 482 | }; |
| 483 | enum mmap_action_type type; | 483 | enum mmap_action_type type; |
| 484 | 484 | ||
| 485 | /* | ||
| 486 | * If specified, this hook is invoked after the selected action has been | ||
| 487 | * successfully completed. Note that the VMA write lock still held. | ||
| 488 | * | ||
| 489 | * The absolute minimum ought to be done here. | ||
| 490 | * | ||
| 491 | * Returns 0 on success, or an error code. | ||
| 492 | */ | ||
| 493 | int (*success_hook)(const struct vm_area_struct *vma); | ||
| 494 | |||
| 495 | /* | 485 | /* |
| 496 | * If specified, this hook is invoked when an error occurred when | 486 | * If specified, this hook is invoked when an error occurred when |
| 497 | * attempting the selection action. | 487 | * attempting the selection action. |