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, 17 insertions, 3 deletions

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)