"Aneesh Kumar K.V" <aneesh.ku...@linux.vnet.ibm.com> writes:
> From: "Aneesh Kumar K.V" <aneesh.ku...@linux.vnet.ibm.com>
>
> We find all the overlapping vma and mark them such that we don't allocate
> hugepage in that range. Also we split existing huge page so that the
> normal page hash can be invalidated and new page faulted in with new
> protection bits.
>
> Signed-off-by: Aneesh Kumar K.V <aneesh.ku...@linux.vnet.ibm.com>
> ---
> arch/powerpc/mm/subpage-prot.c | 27 +++++++++++++++++++++++++++
> 1 file changed, 27 insertions(+)
>
> diff --git a/arch/powerpc/mm/subpage-prot.c b/arch/powerpc/mm/subpage-prot.c
> index 7c415dd..33fd329 100644
> --- a/arch/powerpc/mm/subpage-prot.c
> +++ b/arch/powerpc/mm/subpage-prot.c
> @@ -130,6 +130,14 @@ static void subpage_prot_clear(unsigned long addr,
> unsigned long len)
> up_write(&mm->mmap_sem);
> }
>
> +static int subpage_walk_pmd_entry(pmd_t *pmd, unsigned long addr,
> + unsigned long end, struct mm_walk *walk)
> +{
> + struct vm_area_struct *vma = walk->private;
> + split_huge_page_pmd(vma, addr, pmd);
> + return 0;
> +}
> +
> /*
> * Copy in a subpage protection map for an address range.
> * The map has 2 bits per 4k subpage, so 32 bits per 64k page.
> @@ -149,6 +157,12 @@ long sys_subpage_prot(unsigned long addr, unsigned long
> len, u32 __user *map)
> size_t nw;
> unsigned long next, limit;
> int err;
> + struct vm_area_struct *vma;
> +
> + struct mm_walk subpage_proto_walk = {
> + .mm = mm,
> + .pmd_entry = subpage_walk_pmd_entry,
> + };
>
> /* Check parameters */
> if ((addr & ~PAGE_MASK) || (len & ~PAGE_MASK) ||
> @@ -168,6 +182,19 @@ long sys_subpage_prot(unsigned long addr, unsigned long
> len, u32 __user *map)
> return -EFAULT;
>
> down_write(&mm->mmap_sem);
> +
> + /*
> + * We don't try too hard, we just mark all the vma in that range
> + * VM_NOHUGEPAGE and split them.
> + */
> + for (vma = find_vma(mm, addr);
> + (vma && vma->vm_end < (addr + len)); vma = vma->vm_next) {
should be, Missed commit -amend
(vma && vma->vm_start < (addr + len)); vma = vma->vm_next) {
> + vma->vm_flags |= VM_NOHUGEPAGE;
> + subpage_proto_walk.private = vma;
> + walk_page_range(vma->vm_start, vma->vm_end,
> + &subpage_proto_walk);
> + }
> for (limit = addr + len; addr < limit; addr = next) {
> next = pmd_addr_end(addr, limit);
> err = -ENOMEM;
-aneesh
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