mm/vma: remove mmap_action->success_hook

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.

Lorenzo Stoakes committed 5 months ago

Commit 8876dc01 parent 17986193 files · +0 −22Browse files

Unified · Split

3 files

include/linux/mm_types.h +0 −10
mm/util.c +0 −2
tools/testing/vma/include/dup.h +0 −10

include/linux/mm_types.h+0−10

@@ -843,16 +843,6 @@ struct mmap_action { · 842 unmodified lines
843	843	};
844	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	847	* If specified, this hook is invoked when an error occurred when
858	848	* attempting the selected action.

mm/util.c+0−2

@@ -1397,8 +1397,6 @@ static int mmap_action_finish(struct vm_area_struct *vma, · 1396 unmodified lines
1397	1397
1398	1398	if (!err)
1399	1399	err = call_vma_mapped(vma);
1400		− if (!err && action->success_hook)
1401		− err = action->success_hook(vma);
1402	1400
1403	1401	/* do_munmap() might take rmap lock, so release if held. */
1404	1402	maybe_rmap_unlock_action(vma, action);

tools/testing/vma/include/dup.h+0−10

@@ -482,16 +482,6 @@ struct mmap_action { · 481 unmodified lines
482	482	};
483	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	486	* If specified, this hook is invoked when an error occurred when
497	487	* attempting the selection action.