v4.19.13 snapshot.
diff --git a/include/linux/rmap.h b/include/linux/rmap.h
new file mode 100644
index 0000000..988d176
--- /dev/null
+++ b/include/linux/rmap.h
@@ -0,0 +1,302 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_RMAP_H
+#define _LINUX_RMAP_H
+/*
+ * Declarations for Reverse Mapping functions in mm/rmap.c
+ */
+
+#include <linux/list.h>
+#include <linux/slab.h>
+#include <linux/mm.h>
+#include <linux/rwsem.h>
+#include <linux/memcontrol.h>
+#include <linux/highmem.h>
+
+/*
+ * The anon_vma heads a list of private "related" vmas, to scan if
+ * an anonymous page pointing to this anon_vma needs to be unmapped:
+ * the vmas on the list will be related by forking, or by splitting.
+ *
+ * Since vmas come and go as they are split and merged (particularly
+ * in mprotect), the mapping field of an anonymous page cannot point
+ * directly to a vma: instead it points to an anon_vma, on whose list
+ * the related vmas can be easily linked or unlinked.
+ *
+ * After unlinking the last vma on the list, we must garbage collect
+ * the anon_vma object itself: we're guaranteed no page can be
+ * pointing to this anon_vma once its vma list is empty.
+ */
+struct anon_vma {
+ struct anon_vma *root; /* Root of this anon_vma tree */
+ struct rw_semaphore rwsem; /* W: modification, R: walking the list */
+ /*
+ * The refcount is taken on an anon_vma when there is no
+ * guarantee that the vma of page tables will exist for
+ * the duration of the operation. A caller that takes
+ * the reference is responsible for clearing up the
+ * anon_vma if they are the last user on release
+ */
+ atomic_t refcount;
+
+ /*
+ * Count of child anon_vmas and VMAs which points to this anon_vma.
+ *
+ * This counter is used for making decision about reusing anon_vma
+ * instead of forking new one. See comments in function anon_vma_clone.
+ */
+ unsigned degree;
+
+ struct anon_vma *parent; /* Parent of this anon_vma */
+
+ /*
+ * NOTE: the LSB of the rb_root.rb_node is set by
+ * mm_take_all_locks() _after_ taking the above lock. So the
+ * rb_root must only be read/written after taking the above lock
+ * to be sure to see a valid next pointer. The LSB bit itself
+ * is serialized by a system wide lock only visible to
+ * mm_take_all_locks() (mm_all_locks_mutex).
+ */
+
+ /* Interval tree of private "related" vmas */
+ struct rb_root_cached rb_root;
+};
+
+/*
+ * The copy-on-write semantics of fork mean that an anon_vma
+ * can become associated with multiple processes. Furthermore,
+ * each child process will have its own anon_vma, where new
+ * pages for that process are instantiated.
+ *
+ * This structure allows us to find the anon_vmas associated
+ * with a VMA, or the VMAs associated with an anon_vma.
+ * The "same_vma" list contains the anon_vma_chains linking
+ * all the anon_vmas associated with this VMA.
+ * The "rb" field indexes on an interval tree the anon_vma_chains
+ * which link all the VMAs associated with this anon_vma.
+ */
+struct anon_vma_chain {
+ struct vm_area_struct *vma;
+ struct anon_vma *anon_vma;
+ struct list_head same_vma; /* locked by mmap_sem & page_table_lock */
+ struct rb_node rb; /* locked by anon_vma->rwsem */
+ unsigned long rb_subtree_last;
+#ifdef CONFIG_DEBUG_VM_RB
+ unsigned long cached_vma_start, cached_vma_last;
+#endif
+};
+
+enum ttu_flags {
+ TTU_MIGRATION = 0x1, /* migration mode */
+ TTU_MUNLOCK = 0x2, /* munlock mode */
+
+ TTU_SPLIT_HUGE_PMD = 0x4, /* split huge PMD if any */
+ TTU_IGNORE_MLOCK = 0x8, /* ignore mlock */
+ TTU_IGNORE_ACCESS = 0x10, /* don't age */
+ TTU_IGNORE_HWPOISON = 0x20, /* corrupted page is recoverable */
+ TTU_BATCH_FLUSH = 0x40, /* Batch TLB flushes where possible
+ * and caller guarantees they will
+ * do a final flush if necessary */
+ TTU_RMAP_LOCKED = 0x80, /* do not grab rmap lock:
+ * caller holds it */
+ TTU_SPLIT_FREEZE = 0x100, /* freeze pte under splitting thp */
+};
+
+#ifdef CONFIG_MMU
+static inline void get_anon_vma(struct anon_vma *anon_vma)
+{
+ atomic_inc(&anon_vma->refcount);
+}
+
+void __put_anon_vma(struct anon_vma *anon_vma);
+
+static inline void put_anon_vma(struct anon_vma *anon_vma)
+{
+ if (atomic_dec_and_test(&anon_vma->refcount))
+ __put_anon_vma(anon_vma);
+}
+
+static inline void anon_vma_lock_write(struct anon_vma *anon_vma)
+{
+ down_write(&anon_vma->root->rwsem);
+}
+
+static inline void anon_vma_unlock_write(struct anon_vma *anon_vma)
+{
+ up_write(&anon_vma->root->rwsem);
+}
+
+static inline void anon_vma_lock_read(struct anon_vma *anon_vma)
+{
+ down_read(&anon_vma->root->rwsem);
+}
+
+static inline void anon_vma_unlock_read(struct anon_vma *anon_vma)
+{
+ up_read(&anon_vma->root->rwsem);
+}
+
+
+/*
+ * anon_vma helper functions.
+ */
+void anon_vma_init(void); /* create anon_vma_cachep */
+int __anon_vma_prepare(struct vm_area_struct *);
+void unlink_anon_vmas(struct vm_area_struct *);
+int anon_vma_clone(struct vm_area_struct *, struct vm_area_struct *);
+int anon_vma_fork(struct vm_area_struct *, struct vm_area_struct *);
+
+static inline int anon_vma_prepare(struct vm_area_struct *vma)
+{
+ if (likely(vma->anon_vma))
+ return 0;
+
+ return __anon_vma_prepare(vma);
+}
+
+static inline void anon_vma_merge(struct vm_area_struct *vma,
+ struct vm_area_struct *next)
+{
+ VM_BUG_ON_VMA(vma->anon_vma != next->anon_vma, vma);
+ unlink_anon_vmas(next);
+}
+
+struct anon_vma *page_get_anon_vma(struct page *page);
+
+/* bitflags for do_page_add_anon_rmap() */
+#define RMAP_EXCLUSIVE 0x01
+#define RMAP_COMPOUND 0x02
+
+/*
+ * rmap interfaces called when adding or removing pte of page
+ */
+void page_move_anon_rmap(struct page *, struct vm_area_struct *);
+void page_add_anon_rmap(struct page *, struct vm_area_struct *,
+ unsigned long, bool);
+void do_page_add_anon_rmap(struct page *, struct vm_area_struct *,
+ unsigned long, int);
+void page_add_new_anon_rmap(struct page *, struct vm_area_struct *,
+ unsigned long, bool);
+void page_add_file_rmap(struct page *, bool);
+void page_remove_rmap(struct page *, bool);
+
+void hugepage_add_anon_rmap(struct page *, struct vm_area_struct *,
+ unsigned long);
+void hugepage_add_new_anon_rmap(struct page *, struct vm_area_struct *,
+ unsigned long);
+
+static inline void page_dup_rmap(struct page *page, bool compound)
+{
+ atomic_inc(compound ? compound_mapcount_ptr(page) : &page->_mapcount);
+}
+
+/*
+ * Called from mm/vmscan.c to handle paging out
+ */
+int page_referenced(struct page *, int is_locked,
+ struct mem_cgroup *memcg, unsigned long *vm_flags);
+
+bool try_to_unmap(struct page *, enum ttu_flags flags);
+
+/* Avoid racy checks */
+#define PVMW_SYNC (1 << 0)
+/* Look for migarion entries rather than present PTEs */
+#define PVMW_MIGRATION (1 << 1)
+
+struct page_vma_mapped_walk {
+ struct page *page;
+ struct vm_area_struct *vma;
+ unsigned long address;
+ pmd_t *pmd;
+ pte_t *pte;
+ spinlock_t *ptl;
+ unsigned int flags;
+};
+
+static inline void page_vma_mapped_walk_done(struct page_vma_mapped_walk *pvmw)
+{
+ if (pvmw->pte)
+ pte_unmap(pvmw->pte);
+ if (pvmw->ptl)
+ spin_unlock(pvmw->ptl);
+}
+
+bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw);
+
+/*
+ * Used by swapoff to help locate where page is expected in vma.
+ */
+unsigned long page_address_in_vma(struct page *, struct vm_area_struct *);
+
+/*
+ * Cleans the PTEs of shared mappings.
+ * (and since clean PTEs should also be readonly, write protects them too)
+ *
+ * returns the number of cleaned PTEs.
+ */
+int page_mkclean(struct page *);
+
+/*
+ * called in munlock()/munmap() path to check for other vmas holding
+ * the page mlocked.
+ */
+void try_to_munlock(struct page *);
+
+void remove_migration_ptes(struct page *old, struct page *new, bool locked);
+
+/*
+ * Called by memory-failure.c to kill processes.
+ */
+struct anon_vma *page_lock_anon_vma_read(struct page *page);
+void page_unlock_anon_vma_read(struct anon_vma *anon_vma);
+int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma);
+
+/*
+ * rmap_walk_control: To control rmap traversing for specific needs
+ *
+ * arg: passed to rmap_one() and invalid_vma()
+ * rmap_one: executed on each vma where page is mapped
+ * done: for checking traversing termination condition
+ * anon_lock: for getting anon_lock by optimized way rather than default
+ * invalid_vma: for skipping uninterested vma
+ */
+struct rmap_walk_control {
+ void *arg;
+ /*
+ * Return false if page table scanning in rmap_walk should be stopped.
+ * Otherwise, return true.
+ */
+ bool (*rmap_one)(struct page *page, struct vm_area_struct *vma,
+ unsigned long addr, void *arg);
+ int (*done)(struct page *page);
+ struct anon_vma *(*anon_lock)(struct page *page);
+ bool (*invalid_vma)(struct vm_area_struct *vma, void *arg);
+};
+
+void rmap_walk(struct page *page, struct rmap_walk_control *rwc);
+void rmap_walk_locked(struct page *page, struct rmap_walk_control *rwc);
+
+#else /* !CONFIG_MMU */
+
+#define anon_vma_init() do {} while (0)
+#define anon_vma_prepare(vma) (0)
+#define anon_vma_link(vma) do {} while (0)
+
+static inline int page_referenced(struct page *page, int is_locked,
+ struct mem_cgroup *memcg,
+ unsigned long *vm_flags)
+{
+ *vm_flags = 0;
+ return 0;
+}
+
+#define try_to_unmap(page, refs) false
+
+static inline int page_mkclean(struct page *page)
+{
+ return 0;
+}
+
+
+#endif /* CONFIG_MMU */
+
+#endif /* _LINUX_RMAP_H */