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
  ...

3 files changed, 41 insertions, 11 deletions

diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig
index d8804001d550..6a821e13a98f 100644
--- a/arch/arc/Kconfig
+++ b/arch/arc/Kconfig
@@ -67,6 +67,7 @@ config GENERIC_CSUM
 
 config ARCH_DISCONTIGMEM_ENABLE
 	def_bool n
+	depends on BROKEN
 
 config ARCH_FLATMEM_ENABLE
 	def_bool y
@@ -506,7 +507,7 @@ config LINUX_RAM_BASE
 
 config HIGHMEM
 	bool "High Memory Support"
-	select ARCH_DISCONTIGMEM_ENABLE
+	select HAVE_ARCH_PFN_VALID
 	select KMAP_LOCAL
 	help
 	  With ARC 2G:2G address split, only upper 2G is directly addressable by
diff --git a/arch/arc/include/asm/page.h b/arch/arc/include/asm/page.h
index b0dfed0f12be..23e41e890eda 100644
--- a/arch/arc/include/asm/page.h
+++ b/arch/arc/include/asm/page.h
@@ -82,11 +82,25 @@ typedef pte_t * pgtable_t;
  */
 #define virt_to_pfn(kaddr)	(__pa(kaddr) >> PAGE_SHIFT)
 
-#define ARCH_PFN_OFFSET		virt_to_pfn(CONFIG_LINUX_RAM_BASE)
+/*
+ * When HIGHMEM is enabled we have holes in the memory map so we need
+ * pfn_valid() that takes into account the actual extents of the physical
+ * memory
+ */
+#ifdef CONFIG_HIGHMEM
+
+extern unsigned long arch_pfn_offset;
+#define ARCH_PFN_OFFSET		arch_pfn_offset
+
+extern int pfn_valid(unsigned long pfn);
+#define pfn_valid		pfn_valid
 
-#ifdef CONFIG_FLATMEM
+#else /* CONFIG_HIGHMEM */
+
+#define ARCH_PFN_OFFSET		virt_to_pfn(CONFIG_LINUX_RAM_BASE)
 #define pfn_valid(pfn)		(((pfn) - ARCH_PFN_OFFSET) < max_mapnr)
-#endif
+
+#endif /* CONFIG_HIGHMEM */
 
 /*
  * __pa, __va, virt_to_page (ALERT: deprecated, don't use them)
diff --git a/arch/arc/mm/init.c b/arch/arc/mm/init.c
index 3a35b82a718e..ce07e697916c 100644
--- a/arch/arc/mm/init.c
+++ b/arch/arc/mm/init.c
@@ -28,6 +28,8 @@ static unsigned long low_mem_sz;
 static unsigned long min_high_pfn, max_high_pfn;
 static phys_addr_t high_mem_start;
 static phys_addr_t high_mem_sz;
+unsigned long arch_pfn_offset;
+EXPORT_SYMBOL(arch_pfn_offset);
 #endif
 
 #ifdef CONFIG_DISCONTIGMEM
@@ -98,16 +100,11 @@ void __init setup_arch_memory(void)
 	init_mm.brk = (unsigned long)_end;
 
 	/* first page of system - kernel .vector starts here */
-	min_low_pfn = ARCH_PFN_OFFSET;
+	min_low_pfn = virt_to_pfn(CONFIG_LINUX_RAM_BASE);
 
 	/* Last usable page of low mem */
 	max_low_pfn = max_pfn = PFN_DOWN(low_mem_start + low_mem_sz);
 
-#ifdef CONFIG_FLATMEM
-	/* pfn_valid() uses this */
-	max_mapnr = max_low_pfn - min_low_pfn;
-#endif
-
 	/*------------- bootmem allocator setup -----------------------*/
 
 	/*
@@ -153,7 +150,9 @@ void __init setup_arch_memory(void)
 	 * DISCONTIGMEM in turns requires multiple nodes. node 0 above is
 	 * populated with normal memory zone while node 1 only has highmem
 	 */
+#ifdef CONFIG_DISCONTIGMEM
 	node_set_online(1);
+#endif
 
 	min_high_pfn = PFN_DOWN(high_mem_start);
 	max_high_pfn = PFN_DOWN(high_mem_start + high_mem_sz);
@@ -161,8 +160,15 @@ void __init setup_arch_memory(void)
 	max_zone_pfn[ZONE_HIGHMEM] = min_low_pfn;
 
 	high_memory = (void *)(min_high_pfn << PAGE_SHIFT);
+
+	arch_pfn_offset = min(min_low_pfn, min_high_pfn);
 	kmap_init();
-#endif
+
+#else /* CONFIG_HIGHMEM */
+	/* pfn_valid() uses this when FLATMEM=y and HIGHMEM=n */
+	max_mapnr = max_low_pfn - min_low_pfn;
+
+#endif /* CONFIG_HIGHMEM */
 
 	free_area_init(max_zone_pfn);
 }
@@ -190,3 +196,12 @@ void __init mem_init(void)
 	highmem_init();
 	mem_init_print_info(NULL);
 }
+
+#ifdef CONFIG_HIGHMEM
+int pfn_valid(unsigned long pfn)
+{
+	return (pfn >= min_high_pfn && pfn <= max_high_pfn) ||
+		(pfn >= min_low_pfn && pfn <= max_low_pfn);
+}
+EXPORT_SYMBOL(pfn_valid);
+#endif