On Tue, Jun 20, 2017 at 07:07:11PM -0400, Zi Yan wrote:
> @@ -1220,6 +1238,9 @@ int do_huge_pmd_wp_page(struct vm_fault *vmf, pmd_t orig_pmd)
> if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
> goto out_unlock;
>
> + if (unlikely(!pmd_present(orig_pmd)))
> + goto out_unlock;
> +
Hm. Shouldn't we wait for the page here?
> page = pmd_page(orig_pmd);
> VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page);
> /*
> @@ -1556,6 +1577,12 @@ bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
> if (is_huge_zero_pmd(orig_pmd))
> goto out;
>
> + if (unlikely(!pmd_present(orig_pmd))) {
> + VM_BUG_ON(IS_ENABLED(CONFIG_MIGRATION) &&
> + !is_pmd_migration_entry(orig_pmd));
> + goto out;
> + }
> +
> page = pmd_page(orig_pmd);
> /*
> * If other processes are mapping this page, we couldn't discard
> @@ -1770,6 +1797,23 @@ int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
> preserve_write = prot_numa && pmd_write(*pmd);
> ret = 1;
>
> +#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
> + if (is_swap_pmd(*pmd)) {
> + swp_entry_t entry = pmd_to_swp_entry(*pmd);
> +
> + VM_BUG_ON(IS_ENABLED(CONFIG_MIGRATION) &&
> + !is_pmd_migration_entry(*pmd));
> + if (is_write_migration_entry(entry)) {
> + pmd_t newpmd;
> +
> + make_migration_entry_read(&entry);
> + newpmd = swp_entry_to_pmd(entry);
> + set_pmd_at(mm, addr, pmd, newpmd);
I was confused by this. Could you copy comment from change_pte_range()
here?
> + }
> + goto unlock;
> + }
> +#endif
> +
> /*
> * Avoid trapping faults against the zero page. The read-only
> * data is likely to be read-cached on the local CPU and
--
Kirill A. Shutemov
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