On Saturday, 27 February 2021 2:59:09 AM AEDT Christoph Hellwig wrote: > > - struct page *page = migration_entry_to_page(entry); > > + struct page *page = pfn_to_page(swp_offset(entry)); > > I wonder if keeping a single special_entry_to_page() helper would still > me a useful. But I'm not entirely sure. There are also two more open > coded copies of this in the THP migration code.
I think it might be if only to clearly document where these entries are used. Will add it for the next version to see what it looks like. > > -#define free_swap_and_cache(e) ({(is_migration_entry(e) || is_device_private_entry(e));}) > > -#define swapcache_prepare(e) ({(is_migration_entry(e) || is_device_private_entry(e));}) > > +#define free_swap_and_cache(e) is_special_entry(e) > > +#define swapcache_prepare(e) is_special_entry(e) > > Staring at this I'm really, really confused at what this is doing. > > Looking a little closer these are the !CONFIG_SWAP stubs, but it could > probably use a comment or two. Will do, thanks. - Alistair > > } else if (is_migration_entry(entry)) { > > - page = migration_entry_to_page(entry); > > + page = pfn_to_page(swp_offset(entry)); > > > > rss[mm_counter(page)]++; > > > > @@ -737,7 +737,7 @@ copy_nonpresent_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm, > > set_pte_at(src_mm, addr, src_pte, pte); > > } > > } else if (is_device_private_entry(entry)) { > > - page = device_private_entry_to_page(entry); > > + page = pfn_to_page(swp_offset(entry)); > > > > /* > > * Update rss count even for unaddressable pages, as > > @@ -1274,7 +1274,7 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb, > > > > entry = pte_to_swp_entry(ptent); > > if (is_device_private_entry(entry)) { > > - struct page *page = device_private_entry_to_page(entry); > > + struct page *page = pfn_to_page(swp_offset(entry)); > > > > if (unlikely(details && details->check_mapping)) { > > /* > > @@ -1303,7 +1303,7 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb, > > else if (is_migration_entry(entry)) { > > struct page *page; > > > > - page = migration_entry_to_page(entry); > > + page = pfn_to_page(swp_offset(entry)); > > rss[mm_counter(page)]--; > > } > > if (unlikely(!free_swap_and_cache(entry))) > > @@ -3271,7 +3271,7 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) > > migration_entry_wait(vma->vm_mm, vmf->pmd, > > vmf->address); > > } else if (is_device_private_entry(entry)) { > > - vmf->page = device_private_entry_to_page(entry); > > + vmf->page = pfn_to_page(swp_offset(entry)); > > ret = vmf->page->pgmap->ops->migrate_to_ram(vmf); > > } else if (is_hwpoison_entry(entry)) { > > ret = VM_FAULT_HWPOISON; > > diff --git a/mm/migrate.c b/mm/migrate.c > > index 20ca887ea769..72adcc3d8f5b 100644 > > --- a/mm/migrate.c > > +++ b/mm/migrate.c > > @@ -321,7 +321,7 @@ void __migration_entry_wait(struct mm_struct *mm, pte_t *ptep, > > if (!is_migration_entry(entry)) > > goto out; > > > > - page = migration_entry_to_page(entry); > > + page = pfn_to_page(swp_offset(entry)); > > > > /* > > * Once page cache replacement of page migration started, page_count > > @@ -361,7 +361,7 @@ void pmd_migration_entry_wait(struct mm_struct *mm, pmd_t *pmd) > > ptl = pmd_lock(mm, pmd); > > if (!is_pmd_migration_entry(*pmd)) > > goto unlock; > > - page = migration_entry_to_page(pmd_to_swp_entry(*pmd)); > > + page = pfn_to_page(swp_offset(pmd_to_swp_entry(*pmd))); > > if (!get_page_unless_zero(page)) > > goto unlock; > > spin_unlock(ptl); > > @@ -2437,7 +2437,7 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp, > > if (!is_device_private_entry(entry)) > > goto next; > > > > - page = device_private_entry_to_page(entry); > > + page = pfn_to_page(swp_offset(entry)); > > if (!(migrate->flags & > > MIGRATE_VMA_SELECT_DEVICE_PRIVATE) || > > page->pgmap->owner != migrate->pgmap_owner) > > diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c > > index 86e3a3688d59..34230d08556a 100644 > > --- a/mm/page_vma_mapped.c > > +++ b/mm/page_vma_mapped.c > > @@ -96,7 +96,7 @@ static bool check_pte(struct page_vma_mapped_walk *pvmw) > > if (!is_migration_entry(entry)) > > return false; > > > > - pfn = migration_entry_to_pfn(entry); > > + pfn = swp_offset(entry); > > } else if (is_swap_pte(*pvmw->pte)) { > > swp_entry_t entry; > > > > @@ -105,7 +105,7 @@ static bool check_pte(struct page_vma_mapped_walk *pvmw) > > if (!is_device_private_entry(entry)) > > return false; > > > > - pfn = device_private_entry_to_pfn(entry); > > + pfn = swp_offset(entry); > > } else { > > if (!pte_present(*pvmw->pte)) > > return false; > > @@ -200,7 +200,7 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw) > > if > > (is_migration_entry(pmd_to_swp_entry(*pvmw->pmd))) { > > swp_entry_t entry = > > pmd_to_swp_entry(*pvmw->pmd); > > > > - if (migration_entry_to_page(entry) != > > page) > > + if (pfn_to_page(swp_offset(entry)) != > > page) > > return not_found(pvmw); > > return true; > > } > ---end quoted text--- >