Merge branch 'akpm' (patches from Andrew)

Merge updates from Andrew Morton:
 "A large amount of MM, plenty more to come.

  Subsystems affected by this patch series:
   - tools
   - kthread
   - kbuild
   - scripts
   - ocfs2
   - vfs
   - mm: slub, kmemleak, pagecache, gup, swap, memcg, pagemap, mremap,
         sparsemem, kasan, pagealloc, vmscan, compaction, mempolicy,
         hugetlbfs, hugetlb"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (155 commits)
  include/linux/huge_mm.h: check PageTail in hpage_nr_pages even when !THP
  mm/hugetlb: fix build failure with HUGETLB_PAGE but not HUGEBTLBFS
  selftests/vm: fix map_hugetlb length used for testing read and write
  mm/hugetlb: remove unnecessary memory fetch in PageHeadHuge()
  mm/hugetlb.c: clean code by removing unnecessary initialization
  hugetlb_cgroup: add hugetlb_cgroup reservation docs
  hugetlb_cgroup: add hugetlb_cgroup reservation tests
  hugetlb: support file_region coalescing again
  hugetlb_cgroup: support noreserve mappings
  hugetlb_cgroup: add accounting for shared mappings
  hugetlb: disable region_add file_region coalescing
  hugetlb_cgroup: add reservation accounting for private mappings
  mm/hugetlb_cgroup: fix hugetlb_cgroup migration
  hugetlb_cgroup: add interface for charge/uncharge hugetlb reservations
  hugetlb_cgroup: add hugetlb_cgroup reservation counter
  hugetlbfs: Use i_mmap_rwsem to address page fault/truncate race
  hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization
  mm/memblock.c: remove redundant assignment to variable max_addr
  mm: mempolicy: require at least one nodeid for MPOL_PREFERRED
  mm: mempolicy: use VM_BUG_ON_VMA in queue_pages_test_walk()
  ...

1 files changed, 23 insertions, 6 deletions

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 24ad53b4dfc0..b1e069e68189 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -958,6 +958,11 @@ struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr,
 	 */
 	WARN_ONCE(flags & FOLL_COW, "mm: In follow_devmap_pmd with FOLL_COW set");
 
+	/* FOLL_GET and FOLL_PIN are mutually exclusive. */
+	if (WARN_ON_ONCE((flags & (FOLL_PIN | FOLL_GET)) ==
+			 (FOLL_PIN | FOLL_GET)))
+		return NULL;
+
 	if (flags & FOLL_WRITE && !pmd_write(*pmd))
 		return NULL;
 
@@ -973,7 +978,7 @@ struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr,
 	 * device mapped pages can only be returned if the
 	 * caller will manage the page reference count.
 	 */
-	if (!(flags & FOLL_GET))
+	if (!(flags & (FOLL_GET | FOLL_PIN)))
 		return ERR_PTR(-EEXIST);
 
 	pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT;
@@ -981,7 +986,8 @@ struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr,
 	if (!*pgmap)
 		return ERR_PTR(-EFAULT);
 	page = pfn_to_page(pfn);
-	get_page(page);
+	if (!try_grab_page(page, flags))
+		page = ERR_PTR(-ENOMEM);
 
 	return page;
 }
@@ -1101,6 +1107,11 @@ struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr,
 	if (flags & FOLL_WRITE && !pud_write(*pud))
 		return NULL;
 
+	/* FOLL_GET and FOLL_PIN are mutually exclusive. */
+	if (WARN_ON_ONCE((flags & (FOLL_PIN | FOLL_GET)) ==
+			 (FOLL_PIN | FOLL_GET)))
+		return NULL;
+
 	if (pud_present(*pud) && pud_devmap(*pud))
 		/* pass */;
 	else
@@ -1112,8 +1123,10 @@ struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr,
 	/*
 	 * device mapped pages can only be returned if the
 	 * caller will manage the page reference count.
+	 *
+	 * At least one of FOLL_GET | FOLL_PIN must be set, so assert that here:
 	 */
-	if (!(flags & FOLL_GET))
+	if (!(flags & (FOLL_GET | FOLL_PIN)))
 		return ERR_PTR(-EEXIST);
 
 	pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT;
@@ -1121,7 +1134,8 @@ struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr,
 	if (!*pgmap)
 		return ERR_PTR(-EFAULT);
 	page = pfn_to_page(pfn);
-	get_page(page);
+	if (!try_grab_page(page, flags))
+		page = ERR_PTR(-ENOMEM);
 
 	return page;
 }
@@ -1497,8 +1511,13 @@ struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
 
 	page = pmd_page(*pmd);
 	VM_BUG_ON_PAGE(!PageHead(page) && !is_zone_device_page(page), page);
+
+	if (!try_grab_page(page, flags))
+		return ERR_PTR(-ENOMEM);
+
 	if (flags & FOLL_TOUCH)
 		touch_pmd(vma, addr, pmd, flags);
+
 	if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
 		/*
 		 * We don't mlock() pte-mapped THPs. This way we can avoid
@@ -1535,8 +1554,6 @@ struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
 skip_mlock:
 	page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
 	VM_BUG_ON_PAGE(!PageCompound(page) && !is_zone_device_page(page), page);
-	if (flags & FOLL_GET)
-		get_page(page);
 
 out:
 	return page;