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. Signed-off-by: Lorenzo Stoakes <[email protected]> Reviewed-by: Vlastimil Babka <[email protected]> --- mm/mremap.c | 58 ++++++++++++++++++++++++++--------------------------- 1 file changed, 28 insertions(+), 30 deletions(-) diff --git a/mm/mremap.c b/mm/mremap.c index a00da0288c37..d57645573e0d 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -1636,7 +1636,6 @@ 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) @@ -1651,16 +1650,8 @@ 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; } /* @@ -1716,10 +1707,33 @@ 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); @@ -1733,26 +1747,10 @@ 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); -- 2.50.0
