Merge tag 'libnvdimm-fixes-4.19-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm

Dan writes:
"libnvdimm/dax 4.19-rc8

* Fix a livelock in dax_layout_busy_page() present since v4.18. The
lockup triggers when truncating an actively mapped huge page out of
a mapping pinned for direct-I/O.

* Fix mprotect() clobbers of _PAGE_DEVMAP. Broken since v4.5
mprotect() clears this flag that is needed to communicate the
liveness of device pages to the get_user_pages() path."

* tag 'libnvdimm-fixes-4.19-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm:
mm: Preserve _PAGE_DEVMAP across mprotect() calls
filesystem-dax: Fix dax_layout_busy_page() livelock

arch/powerpc/include/asm/book3s/64/pgtable.h

···
  */
 #define _HPAGE_CHG_MASK (PTE_RPN_MASK | _PAGE_HPTEFLAGS | _PAGE_DIRTY | \
 			 _PAGE_ACCESSED | H_PAGE_THP_HUGE | _PAGE_PTE | \
-			 _PAGE_SOFT_DIRTY)
+			 _PAGE_SOFT_DIRTY | _PAGE_DEVMAP)
 /*
  * user access blocked by key
  */
···
  */
 #define _PAGE_CHG_MASK	(PTE_RPN_MASK | _PAGE_HPTEFLAGS | _PAGE_DIRTY | \
 			 _PAGE_ACCESSED | _PAGE_SPECIAL | _PAGE_PTE |	\
-			 _PAGE_SOFT_DIRTY)
+			 _PAGE_SOFT_DIRTY | _PAGE_DEVMAP)
 
 #define H_PTE_PKEY  (H_PTE_PKEY_BIT0 | H_PTE_PKEY_BIT1 | H_PTE_PKEY_BIT2 | \
 		     H_PTE_PKEY_BIT3 | H_PTE_PKEY_BIT4)

arch/x86/include/asm/pgtable_types.h

···
  */
 #define _PAGE_CHG_MASK	(PTE_PFN_MASK | _PAGE_PCD | _PAGE_PWT |		\
 			 _PAGE_SPECIAL | _PAGE_ACCESSED | _PAGE_DIRTY |	\
-			 _PAGE_SOFT_DIRTY)
+			 _PAGE_SOFT_DIRTY | _PAGE_DEVMAP)
 #define _HPAGE_CHG_MASK (_PAGE_CHG_MASK | _PAGE_PSE)
 
 /*

fs/dax.c

···
 	while (index < end && pagevec_lookup_entries(&pvec, mapping, index,
 				min(end - index, (pgoff_t)PAGEVEC_SIZE),
 				indices)) {
+		pgoff_t nr_pages = 1;
+
 		for (i = 0; i < pagevec_count(&pvec); i++) {
 			struct page *pvec_ent = pvec.pages[i];
 			void *entry;
···
 
 			xa_lock_irq(&mapping->i_pages);
 			entry = get_unlocked_mapping_entry(mapping, index, NULL);
-			if (entry)
+			if (entry) {
 				page = dax_busy_page(entry);
+				/*
+				 * Account for multi-order entries at
+				 * the end of the pagevec.
+				 */
+				if (i + 1 >= pagevec_count(&pvec))
+					nr_pages = 1UL << dax_radix_order(entry);
+			}
 			put_unlocked_mapping_entry(mapping, index, entry);
 			xa_unlock_irq(&mapping->i_pages);
 			if (page)
···
 		 */
 		pagevec_remove_exceptionals(&pvec);
 		pagevec_release(&pvec);
-		index++;
+		index += nr_pages;
 
 		if (page)
 			break;