Commit 3b9dbd5e authored by Liam R. Howlett's avatar Liam R. Howlett Committed by Andrew Morton
Browse files

kernel/fork: convert forking to using the vmi iterator 

Avoid using the maple tree interface directly.  This gains type safety.

Link: https://lkml.kernel.org/r/20230120162650.984577-10-Liam.Howlett@oracle.com


Signed-off-by: default avatarLiam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 92fed820

kernel/fork.c

+8 −11
Original line number Diff line number Diff line
@@ -585,8 +585,8 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm, 
	int retval;

	unsigned long charge = 0;

	LIST_HEAD(uf);

	MA_STATE(old_mas, &oldmm->mm_mt, 0, 0);

	MA_STATE(mas, &mm->mm_mt, 0, 0);

	VMA_ITERATOR(old_vmi, oldmm, 0);

	VMA_ITERATOR(vmi, mm, 0);



	uprobe_start_dup_mmap();

	if (mmap_write_lock_killable(oldmm)) {
@@ -613,11 +613,11 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm, 
		goto out;

	khugepaged_fork(mm, oldmm);



	retval = mas_expected_entries(&mas, oldmm->map_count);

	retval = vma_iter_bulk_alloc(&vmi, oldmm->map_count);

	if (retval)

		goto out;



	mas_for_each(&old_mas, mpnt, ULONG_MAX) {

	for_each_vma(old_vmi, mpnt) {

		struct file *file;



		if (mpnt->vm_flags & VM_DONTCOPY) {
@@ -683,11 +683,8 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm, 
			hugetlb_dup_vma_private(tmp);



		/* Link the vma into the MT */

		mas.index = tmp->vm_start;

		mas.last = tmp->vm_end - 1;

		mas_store(&mas, tmp);

		if (mas_is_err(&mas))

			goto fail_nomem_mas_store;

		if (vma_iter_bulk_store(&vmi, tmp))

			goto fail_nomem_vmi_store;



		mm->map_count++;

		if (!(tmp->vm_flags & VM_WIPEONFORK))
@@ -702,7 +699,7 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm, 
	/* a new mm has just been created */

	retval = arch_dup_mmap(oldmm, mm);

loop_out:

	mas_destroy(&mas);

	vma_iter_free(&vmi);

out:

	mmap_write_unlock(mm);

	flush_tlb_mm(oldmm);
@@ -712,7 +709,7 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm, 
	uprobe_end_dup_mmap();

	return retval;



fail_nomem_mas_store:

fail_nomem_vmi_store:

	unlink_anon_vmas(tmp);

fail_nomem_anon_vma_fork:

	mpol_put(vma_policy(tmp));