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SubjectRe: [PATCH 2/5] vrange: Add purged page detection on setting memory non-volatile
> +/**
> + * vrange_check_purged_pte - Checks ptes for purged pages
> + *
> + * Iterates over the ptes in the pmd checking if they have
> + * purged swap entries.
> + *
> + * Sets the vrange_walker.pages_purged to 1 if any were purged.
> + */
> +static int vrange_check_purged_pte(pmd_t *pmd, unsigned long addr,
> + unsigned long end, struct mm_walk *walk)
> +{
> + struct vrange_walker *vw = walk->private;
> + pte_t *pte;
> + spinlock_t *ptl;
> +
> + if (pmd_trans_huge(*pmd))
> + return 0;
> + if (pmd_trans_unstable(pmd))
> + return 0;
> +
> + pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
> + for (; addr != end; pte++, addr += PAGE_SIZE) {
> + if (!pte_present(*pte)) {
> + swp_entry_t vrange_entry = pte_to_swp_entry(*pte);
> +
> + if (unlikely(is_vpurged_entry(vrange_entry))) {
> + vw->page_was_purged = 1;
> + break;

This function only detect there is vpurge entry or not. But
VRANGE_NONVOLATILE should remove all vpurge entries.
Otherwise, non-volatiled range still makes SIGBUS.

> + }
> + }
> + }
> + pte_unmap_unlock(pte - 1, ptl);
> + cond_resched();
> +
> + return 0;
> +}


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