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, 6 insertions, 4 deletions

diff --git a/mm/slab.c b/mm/slab.c
index b1113561b98b..d7c8da9319c7 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -1399,7 +1399,8 @@ static void kmem_freepages(struct kmem_cache *cachep, struct page *page)
 	__ClearPageSlabPfmemalloc(page);
 	__ClearPageSlab(page);
 	page_mapcount_reset(page);
-	page->mapping = NULL;
+	/* In union with page->mapping where page allocator expects NULL */
+	page->slab_cache = NULL;
 
 	if (current->reclaim_state)
 		current->reclaim_state->reclaimed_slab += 1 << order;
@@ -1434,7 +1435,7 @@ static void slab_kernel_map(struct kmem_cache *cachep, void *objp, int map)
 	if (!is_debug_pagealloc_cache(cachep))
 		return;
 
-	kernel_map_pages(virt_to_page(objp), cachep->size / PAGE_SIZE, map);
+	__kernel_map_pages(virt_to_page(objp), cachep->size / PAGE_SIZE, map);
 }
 
 #else
@@ -3416,6 +3417,9 @@ free_done:
 static __always_inline void __cache_free(struct kmem_cache *cachep, void *objp,
 					 unsigned long caller)
 {
+	if (unlikely(slab_want_init_on_free(cachep)))
+		memset(objp, 0, cachep->object_size);
+
 	/* Put the object into the quarantine, don't touch it for now. */
 	if (kasan_slab_free(cachep, objp, _RET_IP_))
 		return;
@@ -3434,8 +3438,6 @@ void ___cache_free(struct kmem_cache *cachep, void *objp,
 	struct array_cache *ac = cpu_cache_get(cachep);
 
 	check_irq_off();
-	if (unlikely(slab_want_init_on_free(cachep)))
-		memset(objp, 0, cachep->object_size);
 	kmemleak_free_recursive(objp, cachep->flags);
 	objp = cache_free_debugcheck(cachep, objp, caller);
 	memcg_slab_free_hook(cachep, &objp, 1);