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    Subject[PATCH 1/19] untangling do_mremap(), part 1
    From

    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)

    Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
    ---
    mm/mremap.c | 88 +++++++++++++++++++++++++++++++++++++----------------------
    1 files changed, 55 insertions(+), 33 deletions(-)

    diff --git a/mm/mremap.c b/mm/mremap.c
    index 97bff25..6776136 100644
    --- a/mm/mremap.c
    +++ b/mm/mremap.c
    @@ -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)
    @@ -340,41 +392,12 @@ 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))
    - goto out;
    - }
    - if (!may_expand_vm(mm, (new_len - old_len) >> PAGE_SHIFT)) {
    - ret = -ENOMEM;
    + vma = vma_to_resize(addr, old_len, new_len, &charged);
    + if (IS_ERR(vma)) {
    + ret = PTR_ERR(vma);
    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;
    }

    --
    1.5.6.5



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