Merge branch 'akpm' (patches from Andrew)

Merge updates from Andrew Morton:

 - a few hot fixes

 - ocfs2 updates

 - almost all of -mm (slab-generic, slab, slub, kmemleak, kasan,
   cleanups, debug, pagecache, memcg, gup, pagemap, memory-hotplug,
   sparsemem, vmalloc, initialization, z3fold, compaction, mempolicy,
   oom-kill, hugetlb, migration, thp, mmap, madvise, shmem, zswap,
   zsmalloc)

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (132 commits)
  mm/zsmalloc.c: fix a -Wunused-function warning
  zswap: do not map same object twice
  zswap: use movable memory if zpool support allocate movable memory
  zpool: add malloc_support_movable to zpool_driver
  shmem: fix obsolete comment in shmem_getpage_gfp()
  mm/madvise: reduce code duplication in error handling paths
  mm: mmap: increase sockets maximum memory size pgoff for 32bits
  mm/mmap.c: refine find_vma_prev() with rb_last()
  riscv: make mmap allocation top-down by default
  mips: use generic mmap top-down layout and brk randomization
  mips: replace arch specific way to determine 32bit task with generic version
  mips: adjust brk randomization offset to fit generic version
  mips: use STACK_TOP when computing mmap base address
  mips: properly account for stack randomization and stack guard gap
  arm: use generic mmap top-down layout and brk randomization
  arm: use STACK_TOP when computing mmap base address
  arm: properly account for stack randomization and stack guard gap
  arm64, mm: make randomization selected by generic topdown mmap layout
  arm64, mm: move generic mmap layout functions to mm
  arm64: consider stack randomization for mmap base only when necessary
  ...

4 files changed, 68 insertions, 24 deletions

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 84fa00497c49..94d38a39d72e 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -26,6 +26,7 @@
 #include <linux/percpu-rwsem.h>
 #include <linux/task_work.h>
 #include <linux/shmem_fs.h>
+#include <linux/khugepaged.h>
 
 #include <linux/uprobes.h>
 
@@ -143,17 +144,19 @@ static loff_t vaddr_to_offset(struct vm_area_struct *vma, unsigned long vaddr)
  *
  * @vma:      vma that holds the pte pointing to page
  * @addr:     address the old @page is mapped at
- * @page:     the cowed page we are replacing by kpage
- * @kpage:    the modified page we replace page by
+ * @old_page: the page we are replacing by new_page
+ * @new_page: the modified page we replace page by
  *
- * Returns 0 on success, -EFAULT on failure.
+ * If @new_page is NULL, only unmap @old_page.
+ *
+ * Returns 0 on success, negative error code otherwise.
  */
 static int __replace_page(struct vm_area_struct *vma, unsigned long addr,
 				struct page *old_page, struct page *new_page)
 {
 	struct mm_struct *mm = vma->vm_mm;
 	struct page_vma_mapped_walk pvmw = {
-		.page = old_page,
+		.page = compound_head(old_page),
 		.vma = vma,
 		.address = addr,
 	};
@@ -164,12 +167,12 @@ static int __replace_page(struct vm_area_struct *vma, unsigned long addr,
 	mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, mm, addr,
 				addr + PAGE_SIZE);
 
-	VM_BUG_ON_PAGE(PageTransHuge(old_page), old_page);
-
-	err = mem_cgroup_try_charge(new_page, vma->vm_mm, GFP_KERNEL, &memcg,
-			false);
-	if (err)
-		return err;
+	if (new_page) {
+		err = mem_cgroup_try_charge(new_page, vma->vm_mm, GFP_KERNEL,
+					    &memcg, false);
+		if (err)
+			return err;
+	}
 
 	/* For try_to_free_swap() and munlock_vma_page() below */
 	lock_page(old_page);
@@ -177,15 +180,20 @@ static int __replace_page(struct vm_area_struct *vma, unsigned long addr,
 	mmu_notifier_invalidate_range_start(&range);
 	err = -EAGAIN;
 	if (!page_vma_mapped_walk(&pvmw)) {
-		mem_cgroup_cancel_charge(new_page, memcg, false);
+		if (new_page)
+			mem_cgroup_cancel_charge(new_page, memcg, false);
 		goto unlock;
 	}
 	VM_BUG_ON_PAGE(addr != pvmw.address, old_page);
 
-	get_page(new_page);
-	page_add_new_anon_rmap(new_page, vma, addr, false);
-	mem_cgroup_commit_charge(new_page, memcg, false, false);
-	lru_cache_add_active_or_unevictable(new_page, vma);
+	if (new_page) {
+		get_page(new_page);
+		page_add_new_anon_rmap(new_page, vma, addr, false);
+		mem_cgroup_commit_charge(new_page, memcg, false, false);
+		lru_cache_add_active_or_unevictable(new_page, vma);
+	} else
+		/* no new page, just dec_mm_counter for old_page */
+		dec_mm_counter(mm, MM_ANONPAGES);
 
 	if (!PageAnon(old_page)) {
 		dec_mm_counter(mm, mm_counter_file(old_page));
@@ -194,8 +202,9 @@ static int __replace_page(struct vm_area_struct *vma, unsigned long addr,
 
 	flush_cache_page(vma, addr, pte_pfn(*pvmw.pte));
 	ptep_clear_flush_notify(vma, addr, pvmw.pte);
-	set_pte_at_notify(mm, addr, pvmw.pte,
-			mk_pte(new_page, vma->vm_page_prot));
+	if (new_page)
+		set_pte_at_notify(mm, addr, pvmw.pte,
+				  mk_pte(new_page, vma->vm_page_prot));
 
 	page_remove_rmap(old_page, false);
 	if (!page_mapped(old_page))
@@ -464,6 +473,7 @@ int uprobe_write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm,
 	struct page *old_page, *new_page;
 	struct vm_area_struct *vma;
 	int ret, is_register, ref_ctr_updated = 0;
+	bool orig_page_huge = false;
 
 	is_register = is_swbp_insn(&opcode);
 	uprobe = container_of(auprobe, struct uprobe, arch);
@@ -471,7 +481,7 @@ int uprobe_write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm,
 retry:
 	/* Read the page with vaddr into memory */
 	ret = get_user_pages_remote(NULL, mm, vaddr, 1,
-			FOLL_FORCE | FOLL_SPLIT, &old_page, &vma, NULL);
+			FOLL_FORCE | FOLL_SPLIT_PMD, &old_page, &vma, NULL);
 	if (ret <= 0)
 		return ret;
 
@@ -488,6 +498,10 @@ retry:
 		ref_ctr_updated = 1;
 	}
 
+	ret = 0;
+	if (!is_register && !PageAnon(old_page))
+		goto put_old;
+
 	ret = anon_vma_prepare(vma);
 	if (ret)
 		goto put_old;
@@ -501,8 +515,33 @@ retry:
 	copy_highpage(new_page, old_page);
 	copy_to_page(new_page, vaddr, &opcode, UPROBE_SWBP_INSN_SIZE);
 
+	if (!is_register) {
+		struct page *orig_page;
+		pgoff_t index;
+
+		VM_BUG_ON_PAGE(!PageAnon(old_page), old_page);
+
+		index = vaddr_to_offset(vma, vaddr & PAGE_MASK) >> PAGE_SHIFT;
+		orig_page = find_get_page(vma->vm_file->f_inode->i_mapping,
+					  index);
+
+		if (orig_page) {
+			if (PageUptodate(orig_page) &&
+			    pages_identical(new_page, orig_page)) {
+				/* let go new_page */
+				put_page(new_page);
+				new_page = NULL;
+
+				if (PageCompound(orig_page))
+					orig_page_huge = true;
+			}
+			put_page(orig_page);
+		}
+	}
+
 	ret = __replace_page(vma, vaddr, old_page, new_page);
-	put_page(new_page);
+	if (new_page)
+		put_page(new_page);
 put_old:
 	put_page(old_page);
 
@@ -513,6 +552,10 @@ put_old:
 	if (ret && is_register && ref_ctr_updated)
 		update_ref_ctr(uprobe, mm, -1);
 
+	/* try collapse pmd for compound page */
+	if (!ret && orig_page_huge)
+		collapse_pte_mapped_thp(mm, vaddr);
+
 	return ret;
 }
 
diff --git a/kernel/resource.c b/kernel/resource.c
index 74877e9d90ca..76036a41143b 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -487,8 +487,8 @@ int walk_system_ram_range(unsigned long start_pfn, unsigned long nr_pages,
 	while (start < end &&
 	       !find_next_iomem_res(start, end, flags, IORES_DESC_NONE,
 				    false, &res)) {
-		pfn = (res.start + PAGE_SIZE - 1) >> PAGE_SHIFT;
-		end_pfn = (res.end + 1) >> PAGE_SHIFT;
+		pfn = PFN_UP(res.start);
+		end_pfn = PFN_DOWN(res.end + 1);
 		if (end_pfn > pfn)
 			ret = (*func)(pfn, end_pfn - pfn, arg);
 		if (ret)
diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
index c892c6280c9f..8dad5aa600ea 100644
--- a/kernel/sched/idle.c
+++ b/kernel/sched/idle.c
@@ -238,7 +238,6 @@ static void do_idle(void)
 	tick_nohz_idle_enter();
 
 	while (!need_resched()) {
-		check_pgt_cache();
 		rmb();
 
 		local_irq_disable();
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 078950d9605b..00fcea236eba 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -264,7 +264,8 @@ extern struct ctl_table epoll_table[];
 extern struct ctl_table firmware_config_table[];
 #endif
 
-#ifdef HAVE_ARCH_PICK_MMAP_LAYOUT
+#if defined(HAVE_ARCH_PICK_MMAP_LAYOUT) || \
+    defined(CONFIG_ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT)
 int sysctl_legacy_va_layout;
 #endif
 
@@ -1573,7 +1574,8 @@ static struct ctl_table vm_table[] = {
 		.proc_handler	= proc_dointvec,
 		.extra1		= SYSCTL_ZERO,
 	},
-#ifdef HAVE_ARCH_PICK_MMAP_LAYOUT
+#if defined(HAVE_ARCH_PICK_MMAP_LAYOUT) || \
+    defined(CONFIG_ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT)
 	{
 		.procname	= "legacy_va_layout",
 		.data		= &sysctl_legacy_va_layout,