Merge branch 'akpm' (patches from Andrew)

Merge misc updates from Andrew Morton:

 - a few random little subsystems

 - almost all of the MM patches which are staged ahead of linux-next
   material. I'll trickle to post-linux-next work in as the dependents
   get merged up.

Subsystems affected by this patch series: kthread, kbuild, ide, ntfs,
ocfs2, arch, and mm (slab-generic, slab, slub, dax, debug, pagecache,
gup, swap, shmem, memcg, pagemap, mremap, hmm, vmalloc, documentation,
kasan, pagealloc, memory-failure, hugetlb, vmscan, z3fold, compaction,
oom-kill, migration, cma, page-poison, userfaultfd, zswap, zsmalloc,
uaccess, zram, and cleanups).

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (200 commits)
  mm: cleanup kstrto*() usage
  mm: fix fall-through warnings for Clang
  mm: slub: convert sysfs sprintf family to sysfs_emit/sysfs_emit_at
  mm: shmem: convert shmem_enabled_show to use sysfs_emit_at
  mm:backing-dev: use sysfs_emit in macro defining functions
  mm: huge_memory: convert remaining use of sprintf to sysfs_emit and neatening
  mm: use sysfs_emit for struct kobject * uses
  mm: fix kernel-doc markups
  zram: break the strict dependency from lzo
  zram: add stat to gather incompressible pages since zram set up
  zram: support page writeback
  mm/process_vm_access: remove redundant initialization of iov_r
  mm/zsmalloc.c: rework the list_add code in insert_zspage()
  mm/zswap: move to use crypto_acomp API for hardware acceleration
  mm/zswap: fix passing zero to 'PTR_ERR' warning
  mm/zswap: make struct kernel_param_ops definitions const
  userfaultfd/selftests: hint the test runner on required privilege
  userfaultfd/selftests: fix retval check for userfaultfd_open()
  userfaultfd/selftests: always dump something in modes
  userfaultfd: selftests: make __{s,u}64 format specifiers portable
  ...

1 files changed, 14 insertions, 18 deletions

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 63b2e46b6555..e0a561c550b3 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -596,8 +596,7 @@ void generic_online_page(struct page *page, unsigned int order)
 	 * so we should map it first. This is better than introducing a special
 	 * case in page freeing fast path.
 	 */
-	if (debug_pagealloc_enabled_static())
-		kernel_map_pages(page, 1 << order, 1);
+	debug_pagealloc_map_pages(page, 1 << order);
 	__free_pages_core(page, order);
 	totalram_pages_add(1UL << order);
 #ifdef CONFIG_HIGHMEM
@@ -1304,7 +1303,7 @@ do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
 			if (WARN_ON(PageLRU(page)))
 				isolate_lru_page(page);
 			if (page_mapped(page))
-				try_to_unmap(page, TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS);
+				try_to_unmap(page, TTU_IGNORE_MLOCK);
 			continue;
 		}
 
@@ -1492,13 +1491,19 @@ int __ref offline_pages(unsigned long start_pfn, unsigned long nr_pages)
 	}
 	node = zone_to_nid(zone);
 
+	/*
+	 * Disable pcplists so that page isolation cannot race with freeing
+	 * in a way that pages from isolated pageblock are left on pcplists.
+	 */
+	zone_pcp_disable(zone);
+
 	/* set above range as isolated */
 	ret = start_isolate_page_range(start_pfn, end_pfn,
 				       MIGRATE_MOVABLE,
 				       MEMORY_OFFLINE | REPORT_FAILURE);
 	if (ret) {
 		reason = "failure to isolate range";
-		goto failed_removal;
+		goto failed_removal_pcplists_disabled;
 	}
 
 	arg.start_pfn = start_pfn;
@@ -1550,21 +1555,8 @@ int __ref offline_pages(unsigned long start_pfn, unsigned long nr_pages)
 			goto failed_removal_isolated;
 		}
 
-		/*
-		 * per-cpu pages are drained in start_isolate_page_range, but if
-		 * there are still pages that are not free, make sure that we
-		 * drain again, because when we isolated range we might
-		 * have raced with another thread that was adding pages to pcp
-		 * list.
-		 *
-		 * Forward progress should be still guaranteed because
-		 * pages on the pcp list can only belong to MOVABLE_ZONE
-		 * because has_unmovable_pages explicitly checks for
-		 * PageBuddy on freed pages on other zones.
-		 */
 		ret = test_pages_isolated(start_pfn, end_pfn, MEMORY_OFFLINE);
-		if (ret)
-			drain_all_pages(zone);
+
 	} while (ret);
 
 	/* Mark all sections offline and remove free pages from the buddy. */
@@ -1580,6 +1572,8 @@ int __ref offline_pages(unsigned long start_pfn, unsigned long nr_pages)
 	zone->nr_isolate_pageblock -= nr_pages / pageblock_nr_pages;
 	spin_unlock_irqrestore(&zone->lock, flags);
 
+	zone_pcp_enable(zone);
+
 	/* removal success */
 	adjust_managed_page_count(pfn_to_page(start_pfn), -nr_pages);
 	zone->present_pages -= nr_pages;
@@ -1612,6 +1606,8 @@ int __ref offline_pages(unsigned long start_pfn, unsigned long nr_pages)
 failed_removal_isolated:
 	undo_isolate_page_range(start_pfn, end_pfn, MIGRATE_MOVABLE);
 	memory_notify(MEM_CANCEL_OFFLINE, &arg);
+failed_removal_pcplists_disabled:
+	zone_pcp_enable(zone);
 failed_removal:
 	pr_debug("memory offlining [mem %#010llx-%#010llx] failed due to %s\n",
 		 (unsigned long long) start_pfn << PAGE_SHIFT,