Commit 4b6b0a51 authored by Liam R. Howlett's avatar Liam R. Howlett Committed by Andrew Morton
Browse files

mm/mremap: remove goto from mremap_to() 

mremap_to() has a goto label at the end that doesn't unwind anything. 
Removing the label makes the code cleaner.

This commit also adds documentation to the function.

Link: https://lkml.kernel.org/r/20241018174114.2871880-3-Liam.Howlett@oracle.com


Signed-off-by: default avatarLiam R. Howlett <Liam.Howlett@Oracle.com>
Reviewed-by: default avatarPedro Falcato <pedro.falcato@gmail.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jeff Xu <jeffxu@chromium.org>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 58f10693

mm/mremap.c

+27 −19
Original line number Diff line number Diff line
@@ -887,6 +887,20 @@ static int resize_is_valid(struct vm_area_struct *vma, unsigned long addr, 
	return 0;

}



/*

 * mremap_to() - remap a vma to a new location

 * @addr: The old address

 * @old_len: The old size

 * @new_addr: The target address

 * @new_len: The new size

 * @locked: If the returned vma is locked (VM_LOCKED)

 * @flags: the mremap flags

 * @uf: The mremap userfaultfd context

 * @uf_unmap_early: The userfaultfd unmap early context

 * @uf_unmap: The userfaultfd unmap context

 *

 * Returns: The new address of the vma or an error.

 */

static unsigned long mremap_to(unsigned long addr, unsigned long old_len,

		unsigned long new_addr, unsigned long new_len, bool *locked,

		unsigned long flags, struct vm_userfaultfd_ctx *uf,
@@ -895,18 +909,18 @@ static unsigned long mremap_to(unsigned long addr, unsigned long old_len, 
{

	struct mm_struct *mm = current->mm;

	struct vm_area_struct *vma;

	unsigned long ret = -EINVAL;

	unsigned long ret;

	unsigned long map_flags = 0;



	if (offset_in_page(new_addr))

		goto out;

		return -EINVAL;



	if (new_len > TASK_SIZE || new_addr > TASK_SIZE - new_len)

		goto out;

		return -EINVAL;



	/* Ensure the old/new locations do not overlap */

	if (addr + old_len > new_addr && new_addr + new_len > addr)

		goto out;

		return -EINVAL;



	/*

	 * move_vma() need us to stay 4 maps below the threshold, otherwise
@@ -933,31 +947,28 @@ static unsigned long mremap_to(unsigned long addr, unsigned long old_len, 
		 */

		ret = do_munmap(mm, new_addr, new_len, uf_unmap_early);

		if (ret)

			goto out;

			return ret;

	}



	if (old_len > new_len) {

		ret = do_munmap(mm, addr+new_len, old_len - new_len, uf_unmap);

		if (ret)

			goto out;

			return ret;

		old_len = new_len;

	}



	vma = vma_lookup(mm, addr);

	if (!vma) {

		ret = -EFAULT;

		goto out;

	}

	if (!vma)

		return -EFAULT;



	ret = resize_is_valid(vma, addr, old_len, new_len, flags);

	if (ret)

		goto out;

		return ret;



	/* MREMAP_DONTUNMAP expands by old_len since old_len == new_len */

	if (flags & MREMAP_DONTUNMAP &&

		!may_expand_vm(mm, vma->vm_flags, old_len >> PAGE_SHIFT)) {

		ret = -ENOMEM;

		goto out;

		return -ENOMEM;

	}



	if (flags & MREMAP_FIXED)
@@ -970,17 +981,14 @@ static unsigned long mremap_to(unsigned long addr, unsigned long old_len, 
				((addr - vma->vm_start) >> PAGE_SHIFT),

				map_flags);

	if (IS_ERR_VALUE(ret))

		goto out;

		return ret;



	/* We got a new mapping */

	if (!(flags & MREMAP_FIXED))

		new_addr = ret;



	ret = move_vma(vma, addr, old_len, new_len, new_addr, locked, flags, uf,

		       uf_unmap);



out:

	return ret;

	return move_vma(vma, addr, old_len, new_len, new_addr, locked, flags,

			uf, uf_unmap);

}



static int vma_expandable(struct vm_area_struct *vma, unsigned long delta)