Commit f256a7a4 authored by Lorenzo Stoakes's avatar Lorenzo Stoakes Committed by Andrew Morton
Browse files

mm/mremap: put VMA check and prep logic into helper function 

Rather than lumping everything together in do_mremap(), add a new helper
function, check_prep_vma(), to do the work relating to each VMA.

This further lays groundwork for subsequent patches which will allow for
batched VMA mremap().

Additionally, if we set vrm->new_addr == vrm->addr when prepping the VMA,
this avoids us needing to do so in the expand VMA mlocked case.

No functional change intended.

Link: https://lkml.kernel.org/r/15efa3c57935f7f8894094b94c1803c2f322c511.1752770784.git.lorenzo.stoakes@oracle.com


Signed-off-by: default avatarLorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: default avatarVlastimil Babka <vbabka@suse.cz>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rik van Riel <riel@surriel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 3215eace

mm/mremap.c

+28 −30
Original line number Diff line number Diff line
@@ -1634,7 +1634,6 @@ static bool align_hugetlb(struct vma_remap_struct *vrm) 
static unsigned long expand_vma(struct vma_remap_struct *vrm)

{

	unsigned long err;

	unsigned long addr = vrm->addr;



	err = remap_is_valid(vrm);

	if (err)
@@ -1649,16 +1648,8 @@ static unsigned long expand_vma(struct vma_remap_struct *vrm) 
		if (err)

			return err;



		/*

		 * We want to populate the newly expanded portion of the VMA to

		 * satisfy the expectation that mlock()'ing a VMA maintains all

		 * of its pages in memory.

		 */

		if (vrm->mlocked)

			vrm->new_addr = addr;



		/* OK we're done! */

		return addr;

		return vrm->addr;

	}



	/*
@@ -1714,10 +1705,33 @@ static unsigned long mremap_at(struct vma_remap_struct *vrm) 
	return -EINVAL;

}



static int check_prep_vma(struct vma_remap_struct *vrm)

{

	struct vm_area_struct *vma = vrm->vma;



	if (!vma)

		return -EFAULT;



	/* If mseal()'d, mremap() is prohibited. */

	if (!can_modify_vma(vma))

		return -EPERM;



	/* Align to hugetlb page size, if required. */

	if (is_vm_hugetlb_page(vma) && !align_hugetlb(vrm))

		return -EINVAL;



	vrm_set_delta(vrm);

	vrm->remap_type = vrm_remap_type(vrm);

	/* For convenience, we set new_addr even if VMA won't move. */

	if (!vrm_implies_new_addr(vrm))

		vrm->new_addr = vrm->addr;



	return 0;

}



static unsigned long do_mremap(struct vma_remap_struct *vrm)

{

	struct mm_struct *mm = current->mm;

	struct vm_area_struct *vma;

	unsigned long res;



	vrm->old_len = PAGE_ALIGN(vrm->old_len);
@@ -1731,26 +1745,10 @@ static unsigned long do_mremap(struct vma_remap_struct *vrm) 
		return -EINTR;

	vrm->mmap_locked = true;



	vma = vrm->vma = vma_lookup(mm, vrm->addr);

	if (!vma) {

		res = -EFAULT;

		goto out;

	}



	/* If mseal()'d, mremap() is prohibited. */

	if (!can_modify_vma(vma)) {

		res = -EPERM;

		goto out;

	}



	/* Align to hugetlb page size, if required. */

	if (is_vm_hugetlb_page(vma) && !align_hugetlb(vrm)) {

		res = -EINVAL;

	vrm->vma = vma_lookup(current->mm, vrm->addr);

	res = check_prep_vma(vrm);

	if (res)

		goto out;

	}



	vrm_set_delta(vrm);

	vrm->remap_type = vrm_remap_type(vrm);



	/* Actually execute mremap. */

	res = vrm_implies_new_addr(vrm) ? mremap_to(vrm) : mremap_at(vrm);