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spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Jul 04, 2025 at 09:35:03AM +1000, Balbir Singh wrote: > migrate_device code paths go through the collect, setup > and finalize phases of migration. Support for MIGRATE_PFN_COMPOUND > was added earlier in the series to mark THP pages as > MIGRATE_PFN_COMPOUND. > > The entries in src and dst arrays passed to these functions still > remain at a PAGE_SIZE granularity. When a compound page is passed, > the first entry has the PFN along with MIGRATE_PFN_COMPOUND > and other flags set (MIGRATE_PFN_MIGRATE, MIGRATE_PFN_VALID), the > remaining entries (HPAGE_PMD_NR - 1) are filled with 0's. This > representation allows for the compound page to be split into smaller > page sizes. > > migrate_vma_collect_hole(), migrate_vma_collect_pmd() are now THP > page aware. Two new helper functions migrate_vma_collect_huge_pmd() > and migrate_vma_insert_huge_pmd_page() have been added. > > migrate_vma_collect_huge_pmd() can collect THP pages, but if for > some reason this fails, there is fallback support to split the folio > and migrate it. > > migrate_vma_insert_huge_pmd_page() closely follows the logic of > migrate_vma_insert_page() > > Support for splitting pages as needed for migration will follow in > later patches in this series. > > Cc: Karol Herbst > Cc: Lyude Paul > Cc: Danilo Krummrich > Cc: David Airlie > Cc: Simona Vetter > Cc: "Jérôme Glisse" > Cc: Shuah Khan > Cc: David Hildenbrand > Cc: Barry Song > Cc: Baolin Wang > Cc: Ryan Roberts > Cc: Matthew Wilcox > Cc: Peter Xu > Cc: Zi Yan > Cc: Kefeng Wang > Cc: Jane Chu > Cc: Alistair Popple > Cc: Donet Tom > > Signed-off-by: Balbir Singh > --- > mm/migrate_device.c | 437 +++++++++++++++++++++++++++++++++++++------- > 1 file changed, 376 insertions(+), 61 deletions(-) > > diff --git a/mm/migrate_device.c b/mm/migrate_device.c > index e05e14d6eacd..41d0bd787969 100644 > --- a/mm/migrate_device.c > +++ b/mm/migrate_device.c > @@ -14,6 +14,7 @@ > #include > #include > #include > +#include > #include > #include "internal.h" > > @@ -44,6 +45,23 @@ static int migrate_vma_collect_hole(unsigned long start, > if (!vma_is_anonymous(walk->vma)) > return migrate_vma_collect_skip(start, end, walk); > > + if (thp_migration_supported() && > + (migrate->flags & MIGRATE_VMA_SELECT_COMPOUND) && > + (IS_ALIGNED(start, HPAGE_PMD_SIZE) && > + IS_ALIGNED(end, HPAGE_PMD_SIZE))) { > + migrate->src[migrate->npages] = MIGRATE_PFN_MIGRATE | > + MIGRATE_PFN_COMPOUND; > + migrate->dst[migrate->npages] = 0; > + migrate->npages++; > + migrate->cpages++; > + > + /* > + * Collect the remaining entries as holes, in case we > + * need to split later > + */ > + return migrate_vma_collect_skip(start + PAGE_SIZE, end, walk); > + } > + > for (addr = start; addr < end; addr += PAGE_SIZE) { > migrate->src[migrate->npages] = MIGRATE_PFN_MIGRATE; > migrate->dst[migrate->npages] = 0; > @@ -54,57 +72,148 @@ static int migrate_vma_collect_hole(unsigned long start, > return 0; > } > > -static int migrate_vma_collect_pmd(pmd_t *pmdp, > - unsigned long start, > - unsigned long end, > - struct mm_walk *walk) > +/** > + * migrate_vma_collect_huge_pmd - collect THP pages without splitting the > + * folio for device private pages. > + * @pmdp: pointer to pmd entry > + * @start: start address of the range for migration > + * @end: end address of the range for migration > + * @walk: mm_walk callback structure > + * > + * Collect the huge pmd entry at @pmdp for migration and set the > + * MIGRATE_PFN_COMPOUND flag in the migrate src entry to indicate that > + * migration will occur at HPAGE_PMD granularity > + */ > +static int migrate_vma_collect_huge_pmd(pmd_t *pmdp, unsigned long start, > + unsigned long end, struct mm_walk *walk, > + struct folio *fault_folio) > { > + struct mm_struct *mm = walk->mm; > + struct folio *folio; > struct migrate_vma *migrate = walk->private; > - struct folio *fault_folio = migrate->fault_page ? > - page_folio(migrate->fault_page) : NULL; > - struct vm_area_struct *vma = walk->vma; > - struct mm_struct *mm = vma->vm_mm; > - unsigned long addr = start, unmapped = 0; > spinlock_t *ptl; > - pte_t *ptep; > + swp_entry_t entry; > + int ret; > + unsigned long write = 0; > > -again: > - if (pmd_none(*pmdp)) > + ptl = pmd_lock(mm, pmdp); > + if (pmd_none(*pmdp)) { > + spin_unlock(ptl); > return migrate_vma_collect_hole(start, end, -1, walk); > + } > > if (pmd_trans_huge(*pmdp)) { > - struct folio *folio; > - > - ptl = pmd_lock(mm, pmdp); > - if (unlikely(!pmd_trans_huge(*pmdp))) { > + if (!(migrate->flags & MIGRATE_VMA_SELECT_SYSTEM)) { > spin_unlock(ptl); > - goto again; > + return migrate_vma_collect_skip(start, end, walk); > } > > folio = pmd_folio(*pmdp); > if (is_huge_zero_folio(folio)) { > spin_unlock(ptl); > - split_huge_pmd(vma, pmdp, addr); > - } else { > - int ret; > + return migrate_vma_collect_hole(start, end, -1, walk); > + } > + if (pmd_write(*pmdp)) > + write = MIGRATE_PFN_WRITE; > + } else if (!pmd_present(*pmdp)) { > + entry = pmd_to_swp_entry(*pmdp); > + folio = pfn_swap_entry_folio(entry); > + > + if (!is_device_private_entry(entry) || > + !(migrate->flags & MIGRATE_VMA_SELECT_DEVICE_PRIVATE) || > + (folio->pgmap->owner != migrate->pgmap_owner)) { > + spin_unlock(ptl); > + return migrate_vma_collect_skip(start, end, walk); > + } > > - folio_get(folio); > + if (is_migration_entry(entry)) { > + migration_entry_wait_on_locked(entry, ptl); > spin_unlock(ptl); > - /* FIXME: we don't expect THP for fault_folio */ > - if (WARN_ON_ONCE(fault_folio == folio)) > - return migrate_vma_collect_skip(start, end, > - walk); > - if (unlikely(!folio_trylock(folio))) > - return migrate_vma_collect_skip(start, end, > - walk); > - ret = split_folio(folio); > - if (fault_folio != folio) > - folio_unlock(folio); > - folio_put(folio); > - if (ret) > - return migrate_vma_collect_skip(start, end, > - walk); > + return -EAGAIN; > } > + > + if (is_writable_device_private_entry(entry)) > + write = MIGRATE_PFN_WRITE; > + } else { > + spin_unlock(ptl); > + return -EAGAIN; > + } > + > + folio_get(folio); > + if (folio != fault_folio && unlikely(!folio_trylock(folio))) { > + spin_unlock(ptl); > + folio_put(folio); > + return migrate_vma_collect_skip(start, end, walk); > + } > + > + if (thp_migration_supported() && > + (migrate->flags & MIGRATE_VMA_SELECT_COMPOUND) && > + (IS_ALIGNED(start, HPAGE_PMD_SIZE) && > + IS_ALIGNED(end, HPAGE_PMD_SIZE))) { > + > + struct page_vma_mapped_walk pvmw = { > + .ptl = ptl, > + .address = start, > + .pmd = pmdp, > + .vma = walk->vma, > + }; > + > + unsigned long pfn = page_to_pfn(folio_page(folio, 0)); > + > + migrate->src[migrate->npages] = migrate_pfn(pfn) | write > + | MIGRATE_PFN_MIGRATE > + | MIGRATE_PFN_COMPOUND; > + migrate->dst[migrate->npages++] = 0; > + migrate->cpages++; > + ret = set_pmd_migration_entry(&pvmw, folio_page(folio, 0)); > + if (ret) { > + migrate->npages--; > + migrate->cpages--; > + migrate->src[migrate->npages] = 0; > + migrate->dst[migrate->npages] = 0; > + goto fallback; > + } > + migrate_vma_collect_skip(start + PAGE_SIZE, end, walk); > + spin_unlock(ptl); > + return 0; > + } > + > +fallback: > + spin_unlock(ptl); > + ret = split_folio(folio); > + if (fault_folio != folio) > + folio_unlock(folio); > + folio_put(folio); > + if (ret) > + return migrate_vma_collect_skip(start, end, walk); > + if (pmd_none(pmdp_get_lockless(pmdp))) > + return migrate_vma_collect_hole(start, end, -1, walk); > + > + return -ENOENT; > +} > + > +static int migrate_vma_collect_pmd(pmd_t *pmdp, > + unsigned long start, > + unsigned long end, > + struct mm_walk *walk) > +{ > + struct migrate_vma *migrate = walk->private; > + struct vm_area_struct *vma = walk->vma; > + struct mm_struct *mm = vma->vm_mm; > + unsigned long addr = start, unmapped = 0; > + spinlock_t *ptl; > + struct folio *fault_folio = migrate->fault_page ? > + page_folio(migrate->fault_page) : NULL; > + pte_t *ptep; > + > +again: > + if (pmd_trans_huge(*pmdp) || !pmd_present(*pmdp)) { > + int ret = migrate_vma_collect_huge_pmd(pmdp, start, end, walk, fault_folio); > + > + if (ret == -EAGAIN) > + goto again; > + if (ret == 0) > + return 0; > } > > ptep = pte_offset_map_lock(mm, pmdp, addr, &ptl); > @@ -175,8 +284,7 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp, > mpfn |= pte_write(pte) ? MIGRATE_PFN_WRITE : 0; > } > > - /* FIXME support THP */ > - if (!page || !page->mapping || PageTransCompound(page)) { > + if (!page || !page->mapping) { > mpfn = 0; > goto next; > } > @@ -347,14 +455,6 @@ static bool migrate_vma_check_page(struct page *page, struct page *fault_page) > */ > int extra = 1 + (page == fault_page); > > - /* > - * FIXME support THP (transparent huge page), it is bit more complex to > - * check them than regular pages, because they can be mapped with a pmd > - * or with a pte (split pte mapping). > - */ > - if (folio_test_large(folio)) > - return false; > - > /* Page from ZONE_DEVICE have one extra reference */ > if (folio_is_zone_device(folio)) > extra++; > @@ -385,17 +485,24 @@ static unsigned long migrate_device_unmap(unsigned long *src_pfns, > > lru_add_drain(); > > - for (i = 0; i < npages; i++) { > + for (i = 0; i < npages; ) { > struct page *page = migrate_pfn_to_page(src_pfns[i]); > struct folio *folio; > + unsigned int nr = 1; > > if (!page) { > if (src_pfns[i] & MIGRATE_PFN_MIGRATE) > unmapped++; > - continue; > + goto next; > } > > folio = page_folio(page); > + nr = folio_nr_pages(folio); > + > + if (nr > 1) > + src_pfns[i] |= MIGRATE_PFN_COMPOUND; > + > + > /* ZONE_DEVICE folios are not on LRU */ > if (!folio_is_zone_device(folio)) { > if (!folio_test_lru(folio) && allow_drain) { > @@ -407,7 +514,7 @@ static unsigned long migrate_device_unmap(unsigned long *src_pfns, > if (!folio_isolate_lru(folio)) { > src_pfns[i] &= ~MIGRATE_PFN_MIGRATE; > restore++; > - continue; > + goto next; > } > > /* Drop the reference we took in collect */ > @@ -426,10 +533,12 @@ static unsigned long migrate_device_unmap(unsigned long *src_pfns, > > src_pfns[i] &= ~MIGRATE_PFN_MIGRATE; > restore++; > - continue; > + goto next; > } > > unmapped++; > +next: > + i += nr; > } > > for (i = 0; i < npages && restore; i++) { > @@ -575,6 +684,146 @@ int migrate_vma_setup(struct migrate_vma *args) > } > EXPORT_SYMBOL(migrate_vma_setup); > > +#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION > +/** > + * migrate_vma_insert_huge_pmd_page: Insert a huge folio into @migrate->vma->vm_mm > + * at @addr. folio is already allocated as a part of the migration process with > + * large page. > + * > + * @folio needs to be initialized and setup after it's allocated. The code bits > + * here follow closely the code in __do_huge_pmd_anonymous_page(). This API does > + * not support THP zero pages. > + * > + * @migrate: migrate_vma arguments > + * @addr: address where the folio will be inserted > + * @folio: folio to be inserted at @addr > + * @src: src pfn which is being migrated > + * @pmdp: pointer to the pmd > + */ > +static int migrate_vma_insert_huge_pmd_page(struct migrate_vma *migrate, > + unsigned long addr, > + struct page *page, > + unsigned long *src, > + pmd_t *pmdp) > +{ > + struct vm_area_struct *vma = migrate->vma; > + gfp_t gfp = vma_thp_gfp_mask(vma); > + struct folio *folio = page_folio(page); > + int ret; > + spinlock_t *ptl; > + pgtable_t pgtable; > + pmd_t entry; > + bool flush = false; > + unsigned long i; > + > + VM_WARN_ON_FOLIO(!folio, folio); > + VM_WARN_ON_ONCE(!pmd_none(*pmdp) && !is_huge_zero_pmd(*pmdp)); > + > + if (!thp_vma_suitable_order(vma, addr, HPAGE_PMD_ORDER)) > + return -EINVAL; > + > + ret = anon_vma_prepare(vma); > + if (ret) > + return ret; > + > + folio_set_order(folio, HPAGE_PMD_ORDER); > + folio_set_large_rmappable(folio); > + > + if (mem_cgroup_charge(folio, migrate->vma->vm_mm, gfp)) { > + count_vm_event(THP_FAULT_FALLBACK); > + count_mthp_stat(HPAGE_PMD_ORDER, MTHP_STAT_ANON_FAULT_FALLBACK_CHARGE); > + ret = -ENOMEM; > + goto abort; > + } > + > + __folio_mark_uptodate(folio); > + > + pgtable = pte_alloc_one(vma->vm_mm); > + if (unlikely(!pgtable)) > + goto abort; > + > + if (folio_is_device_private(folio)) { > + swp_entry_t swp_entry; > + > + if (vma->vm_flags & VM_WRITE) > + swp_entry = make_writable_device_private_entry( > + page_to_pfn(page)); > + else > + swp_entry = make_readable_device_private_entry( > + page_to_pfn(page)); > + entry = swp_entry_to_pmd(swp_entry); > + } else { > + if (folio_is_zone_device(folio) && > + !folio_is_device_coherent(folio)) { > + goto abort; > + } > + entry = folio_mk_pmd(folio, vma->vm_page_prot); > + if (vma->vm_flags & VM_WRITE) > + entry = pmd_mkwrite(pmd_mkdirty(entry), vma); > + } > + > + ptl = pmd_lock(vma->vm_mm, pmdp); > + ret = check_stable_address_space(vma->vm_mm); > + if (ret) > + goto abort; > + > + /* > + * Check for userfaultfd but do not deliver the fault. Instead, > + * just back off. > + */ > + if (userfaultfd_missing(vma)) > + goto unlock_abort; > + > + if (!pmd_none(*pmdp)) { > + if (!is_huge_zero_pmd(*pmdp)) > + goto unlock_abort; > + flush = true; > + } else if (!pmd_none(*pmdp)) > + goto unlock_abort; > + > + add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR); > + folio_add_new_anon_rmap(folio, vma, addr, RMAP_EXCLUSIVE); > + if (!folio_is_zone_device(folio)) > + folio_add_lru_vma(folio, vma); > + folio_get(folio); > + > + if (flush) { > + pte_free(vma->vm_mm, pgtable); > + flush_cache_page(vma, addr, addr + HPAGE_PMD_SIZE); > + pmdp_invalidate(vma, addr, pmdp); > + } else { > + pgtable_trans_huge_deposit(vma->vm_mm, pmdp, pgtable); > + mm_inc_nr_ptes(vma->vm_mm); > + } > + set_pmd_at(vma->vm_mm, addr, pmdp, entry); > + update_mmu_cache_pmd(vma, addr, pmdp); > + > + spin_unlock(ptl); > + > + count_vm_event(THP_FAULT_ALLOC); > + count_mthp_stat(HPAGE_PMD_ORDER, MTHP_STAT_ANON_FAULT_ALLOC); > + count_memcg_event_mm(vma->vm_mm, THP_FAULT_ALLOC); > + > + return 0; > + > +unlock_abort: > + spin_unlock(ptl); > +abort: > + for (i = 0; i < HPAGE_PMD_NR; i++) > + src[i] &= ~MIGRATE_PFN_MIGRATE; > + return 0; > +} > +#else /* !CONFIG_ARCH_ENABLE_THP_MIGRATION */ > +static int migrate_vma_insert_huge_pmd_page(struct migrate_vma *migrate, > + unsigned long addr, > + struct page *page, > + unsigned long *src, > + pmd_t *pmdp) > +{ > + return 0; > +} > +#endif > + > /* > * This code closely matches the code in: > * __handle_mm_fault() > @@ -585,9 +834,10 @@ EXPORT_SYMBOL(migrate_vma_setup); > */ > static void migrate_vma_insert_page(struct migrate_vma *migrate, > unsigned long addr, > - struct page *page, > + unsigned long *dst, > unsigned long *src) > { > + struct page *page = migrate_pfn_to_page(*dst); > struct folio *folio = page_folio(page); > struct vm_area_struct *vma = migrate->vma; > struct mm_struct *mm = vma->vm_mm; > @@ -615,8 +865,25 @@ static void migrate_vma_insert_page(struct migrate_vma *migrate, > pmdp = pmd_alloc(mm, pudp, addr); > if (!pmdp) > goto abort; > - if (pmd_trans_huge(*pmdp)) > - goto abort; > + > + if (thp_migration_supported() && (*dst & MIGRATE_PFN_COMPOUND)) { > + int ret = migrate_vma_insert_huge_pmd_page(migrate, addr, page, > + src, pmdp); > + if (ret) > + goto abort; > + return; > + } > + > + if (!pmd_none(*pmdp)) { > + if (pmd_trans_huge(*pmdp)) { > + if (!is_huge_zero_pmd(*pmdp)) > + goto abort; > + folio_get(pmd_folio(*pmdp)); > + split_huge_pmd(vma, pmdp, addr); > + } else if (pmd_leaf(*pmdp)) > + goto abort; > + } > + > if (pte_alloc(mm, pmdp)) > goto abort; > if (unlikely(anon_vma_prepare(vma))) > @@ -707,23 +974,24 @@ static void __migrate_device_pages(unsigned long *src_pfns, > unsigned long i; > bool notified = false; > > - for (i = 0; i < npages; i++) { > + for (i = 0; i < npages; ) { > struct page *newpage = migrate_pfn_to_page(dst_pfns[i]); > struct page *page = migrate_pfn_to_page(src_pfns[i]); > struct address_space *mapping; > struct folio *newfolio, *folio; > int r, extra_cnt = 0; > + unsigned long nr = 1; > > if (!newpage) { > src_pfns[i] &= ~MIGRATE_PFN_MIGRATE; > - continue; > + goto next; > } > > if (!page) { > unsigned long addr; > > if (!(src_pfns[i] & MIGRATE_PFN_MIGRATE)) > - continue; > + goto next; > > /* > * The only time there is no vma is when called from > @@ -741,15 +1009,47 @@ static void __migrate_device_pages(unsigned long *src_pfns, > migrate->pgmap_owner); > mmu_notifier_invalidate_range_start(&range); > } > - migrate_vma_insert_page(migrate, addr, newpage, > + > + if ((src_pfns[i] & MIGRATE_PFN_COMPOUND) && > + (!(dst_pfns[i] & MIGRATE_PFN_COMPOUND))) { > + nr = HPAGE_PMD_NR; > + src_pfns[i] &= ~MIGRATE_PFN_COMPOUND; > + src_pfns[i] &= ~MIGRATE_PFN_MIGRATE; > + goto next; > + } > + > + migrate_vma_insert_page(migrate, addr, &dst_pfns[i], > &src_pfns[i]); > - continue; > + goto next; > } > > newfolio = page_folio(newpage); > folio = page_folio(page); > mapping = folio_mapping(folio); > > + /* > + * If THP migration is enabled, check if both src and dst > + * can migrate large pages > + */ > + if (thp_migration_supported()) { > + if ((src_pfns[i] & MIGRATE_PFN_MIGRATE) && > + (src_pfns[i] & MIGRATE_PFN_COMPOUND) && > + !(dst_pfns[i] & MIGRATE_PFN_COMPOUND)) { > + > + if (!migrate) { > + src_pfns[i] &= ~(MIGRATE_PFN_MIGRATE | > + MIGRATE_PFN_COMPOUND); > + goto next; > + } > + src_pfns[i] &= ~MIGRATE_PFN_MIGRATE; > + } else if ((src_pfns[i] & MIGRATE_PFN_MIGRATE) && > + (dst_pfns[i] & MIGRATE_PFN_COMPOUND) && > + !(src_pfns[i] & MIGRATE_PFN_COMPOUND)) { > + src_pfns[i] &= ~MIGRATE_PFN_MIGRATE; > + } > + } > + > + > if (folio_is_device_private(newfolio) || > folio_is_device_coherent(newfolio)) { > if (mapping) { > @@ -762,7 +1062,7 @@ static void __migrate_device_pages(unsigned long *src_pfns, > if (!folio_test_anon(folio) || > !folio_free_swap(folio)) { > src_pfns[i] &= ~MIGRATE_PFN_MIGRATE; > - continue; > + goto next; > } > } > } else if (folio_is_zone_device(newfolio)) { > @@ -770,7 +1070,7 @@ static void __migrate_device_pages(unsigned long *src_pfns, > * Other types of ZONE_DEVICE page are not supported. > */ > src_pfns[i] &= ~MIGRATE_PFN_MIGRATE; > - continue; > + goto next; > } > > BUG_ON(folio_test_writeback(folio)); > @@ -782,6 +1082,8 @@ static void __migrate_device_pages(unsigned long *src_pfns, > src_pfns[i] &= ~MIGRATE_PFN_MIGRATE; > else > folio_migrate_flags(newfolio, folio); > +next: > + i += nr; > } > > if (notified) > @@ -943,10 +1245,23 @@ static unsigned long migrate_device_pfn_lock(unsigned long pfn) > int migrate_device_range(unsigned long *src_pfns, unsigned long start, > unsigned long npages) I think migrate_device_pfns should be updated too in similar way. Here is what I came up with. Again feel free to include or modify these changes as you see fit. * Similar to migrate_device_range() but supports non-contiguous pre-popluated - * array of device pages to migrate. + * array of device pages to migrate. If a higher-order folio is found, the mpfn + * is OR'ed with MIGRATE_PFN_COMPOUND, and the subsequent mpfns within the range + * of the order are cleared. */ int migrate_device_pfns(unsigned long *src_pfns, unsigned long npages) { - unsigned long i; + unsigned long i, j; + + for (i = 0; i < npages; i++) { + struct page *page = pfn_to_page(src_pfns[i]); + struct folio *folio = page_folio(page); + unsigned int nr = 1; - for (i = 0; i < npages; i++) src_pfns[i] = migrate_device_pfn_lock(src_pfns[i]); + nr = folio_nr_pages(folio); + if (nr > 1) { + src_pfns[i] |= MIGRATE_PFN_COMPOUND; + for (j = 1; j < nr; j++) + src_pfns[i+j] = 0; + i += j - 1; + } + } Matt > { > - unsigned long i, pfn; > + unsigned long i, j, pfn; > + > + for (pfn = start, i = 0; i < npages; pfn++, i++) { > + struct page *page = pfn_to_page(pfn); > + struct folio *folio = page_folio(page); > + unsigned int nr = 1; > > - for (pfn = start, i = 0; i < npages; pfn++, i++) > src_pfns[i] = migrate_device_pfn_lock(pfn); > + nr = folio_nr_pages(folio); > + if (nr > 1) { > + src_pfns[i] |= MIGRATE_PFN_COMPOUND; > + for (j = 1; j < nr; j++) > + src_pfns[i+j] = 0; > + i += j - 1; > + pfn += j - 1; > + } > + } > > migrate_device_unmap(src_pfns, npages, NULL); > > -- > 2.49.0 >