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Commit 54f5de70 authored by Al Viro's avatar Al Viro
Browse files

untangling do_mremap(), part 1 



Take locating vma and checks on it to a separate helper (it will be
shared between MREMAP_FIXED/non-MREMAP_FIXED cases when we split
them in the next patch)

Acked-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
Acked-by: default avatarHugh Dickins <hugh.dickins@tiscali.co.uk>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 3ef884b4

mm/mremap.c

+55 −33
Original line number Diff line number Diff line
@@ -261,6 +261,58 @@ static unsigned long move_vma(struct vm_area_struct *vma, 
	return new_addr;

}



static struct vm_area_struct *vma_to_resize(unsigned long addr,

	unsigned long old_len, unsigned long new_len, unsigned long *p)

{

	struct mm_struct *mm = current->mm;

	struct vm_area_struct *vma = find_vma(mm, addr);



	if (!vma || vma->vm_start > addr)

		goto Efault;



	if (is_vm_hugetlb_page(vma))

		goto Einval;



	/* We can't remap across vm area boundaries */

	if (old_len > vma->vm_end - addr)

		goto Efault;



	if (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP)) {

		if (new_len > old_len)

			goto Efault;

	}



	if (vma->vm_flags & VM_LOCKED) {

		unsigned long locked, lock_limit;

		locked = mm->locked_vm << PAGE_SHIFT;

		lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;

		locked += new_len - old_len;

		if (locked > lock_limit && !capable(CAP_IPC_LOCK))

			goto Eagain;

	}



	if (!may_expand_vm(mm, (new_len - old_len) >> PAGE_SHIFT))

		goto Enomem;



	if (vma->vm_flags & VM_ACCOUNT) {

		unsigned long charged = (new_len - old_len) >> PAGE_SHIFT;

		if (security_vm_enough_memory(charged))

			goto Efault;

		*p = charged;

	}



	return vma;



Efault:	/* very odd choice for most of the cases, but... */

	return ERR_PTR(-EFAULT);

Einval:

	return ERR_PTR(-EINVAL);

Enomem:

	return ERR_PTR(-ENOMEM);

Eagain:

	return ERR_PTR(-EAGAIN);

}



/*

 * Expand (or shrink) an existing mapping, potentially moving it at the

 * same time (controlled by the MREMAP_MAYMOVE flag and available VM space)
@@ -340,40 +392,11 @@ unsigned long do_mremap(unsigned long addr, 
	/*

	 * Ok, we need to grow..  or relocate.

	 */

	ret = -EFAULT;

	vma = find_vma(mm, addr);

	if (!vma || vma->vm_start > addr)

		goto out;

	if (is_vm_hugetlb_page(vma)) {

		ret = -EINVAL;

		goto out;

	}

	/* We can't remap across vm area boundaries */

	if (old_len > vma->vm_end - addr)

		goto out;

	if (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP)) {

		if (new_len > old_len)

			goto out;

	}

	if (vma->vm_flags & VM_LOCKED) {

		unsigned long locked, lock_limit;

		locked = mm->locked_vm << PAGE_SHIFT;

		lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;

		locked += new_len - old_len;

		ret = -EAGAIN;

		if (locked > lock_limit && !capable(CAP_IPC_LOCK))

	vma = vma_to_resize(addr, old_len, new_len, &charged);

	if (IS_ERR(vma)) {

		ret = PTR_ERR(vma);

		goto out;

	}

	if (!may_expand_vm(mm, (new_len - old_len) >> PAGE_SHIFT)) {

		ret = -ENOMEM;

		goto out;

	}



	if (vma->vm_flags & VM_ACCOUNT) {

		charged = (new_len - old_len) >> PAGE_SHIFT;

		if (security_vm_enough_memory(charged))

			goto out_nc;

	}



	/* old_len exactly to the end of the area..

	 * And we're not relocating the area.
@@ -430,7 +453,6 @@ unsigned long do_mremap(unsigned long addr, 
out:

	if (ret & ~PAGE_MASK)

		vm_unacct_memory(charged);

out_nc:

	return ret;

}