On 5/20/21 7:48 AM, Peter Xu wrote:
On Wed, May 19, 2021 at 10:16:07AM +0530, Aneesh Kumar K.V wrote:
On Thu, Apr 22, 2021 at 11:13:17AM +0530, Aneesh Kumar K.V wrote:
pmd/pud_populate is the right interface to be used to set the respective
page table entries. Some architectures like ppc64 do assume that set_pmd/pud_at
can only be used to set a hugepage PTE. Since we are not setting up a hugepage
PTE here, use the pmd/pud_populate interface.
[1]
Can you try this change?
modified mm/mremap.c
@@ -279,7 +279,7 @@ static bool move_normal_pmd(struct vm_area_struct *vma, unsigned long old_addr,
pmd_clear(old_pmd);
VM_BUG_ON(!pmd_none(*new_pmd));
- pmd_populate(mm, new_pmd, (pgtable_t)pmd_page_vaddr(pmd));
+ pmd_populate(mm, new_pmd, pmd_pgtable(pmd));
if (new_ptl != old_ptl)
spin_unlock(new_ptl);
I reported this issue today somewhere else:
https://lore.kernel.org/linux-mm/YKVemB5DuSqLFmmz@t490s/
And came to this same line after the bisection.
This seems to work at least for my userfaultfd test on shmem, however I don't
fully understand the commit message [1] on: How do we guarantee we're not
moving a thp pte?
move_page_tables() checks for pmd_trans_huge() and ends up calling
move_huge_pmd if it is a THP entry.
-aneesh
