shmem: add huge pages support
[cascardo/linux.git] / mm / huge_memory.c
index 9ed5853..0f58460 100644 (file)
@@ -30,6 +30,7 @@
 #include <linux/hashtable.h>
 #include <linux/userfaultfd_k.h>
 #include <linux/page_idle.h>
+#include <linux/shmem_fs.h>
 
 #include <asm/tlb.h>
 #include <asm/pgalloc.h>
@@ -57,7 +58,8 @@ enum scan_result {
        SCAN_SWAP_CACHE_PAGE,
        SCAN_DEL_PAGE_LRU,
        SCAN_ALLOC_HUGE_PAGE_FAIL,
-       SCAN_CGROUP_CHARGE_FAIL
+       SCAN_CGROUP_CHARGE_FAIL,
+       SCAN_EXCEED_SWAP_PTE
 };
 
 #define CREATE_TRACE_POINTS
@@ -100,6 +102,7 @@ static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait);
  * fault.
  */
 static unsigned int khugepaged_max_ptes_none __read_mostly;
+static unsigned int khugepaged_max_ptes_swap __read_mostly;
 
 static int khugepaged(void *none);
 static int khugepaged_slab_init(void);
@@ -439,6 +442,9 @@ static struct attribute *hugepage_attr[] = {
        &enabled_attr.attr,
        &defrag_attr.attr,
        &use_zero_page_attr.attr,
+#ifdef CONFIG_SHMEM
+       &shmem_enabled_attr.attr,
+#endif
 #ifdef CONFIG_DEBUG_VM
        &debug_cow_attr.attr,
 #endif
@@ -598,6 +604,33 @@ static struct kobj_attribute khugepaged_max_ptes_none_attr =
        __ATTR(max_ptes_none, 0644, khugepaged_max_ptes_none_show,
               khugepaged_max_ptes_none_store);
 
+static ssize_t khugepaged_max_ptes_swap_show(struct kobject *kobj,
+                                            struct kobj_attribute *attr,
+                                            char *buf)
+{
+       return sprintf(buf, "%u\n", khugepaged_max_ptes_swap);
+}
+
+static ssize_t khugepaged_max_ptes_swap_store(struct kobject *kobj,
+                                             struct kobj_attribute *attr,
+                                             const char *buf, size_t count)
+{
+       int err;
+       unsigned long max_ptes_swap;
+
+       err  = kstrtoul(buf, 10, &max_ptes_swap);
+       if (err || max_ptes_swap > HPAGE_PMD_NR-1)
+               return -EINVAL;
+
+       khugepaged_max_ptes_swap = max_ptes_swap;
+
+       return count;
+}
+
+static struct kobj_attribute khugepaged_max_ptes_swap_attr =
+       __ATTR(max_ptes_swap, 0644, khugepaged_max_ptes_swap_show,
+              khugepaged_max_ptes_swap_store);
+
 static struct attribute *khugepaged_attr[] = {
        &khugepaged_defrag_attr.attr,
        &khugepaged_max_ptes_none_attr.attr,
@@ -606,6 +639,7 @@ static struct attribute *khugepaged_attr[] = {
        &full_scans_attr.attr,
        &scan_sleep_millisecs_attr.attr,
        &alloc_sleep_millisecs_attr.attr,
+       &khugepaged_max_ptes_swap_attr.attr,
        NULL,
 };
 
@@ -674,6 +708,7 @@ static int __init hugepage_init(void)
 
        khugepaged_pages_to_scan = HPAGE_PMD_NR * 8;
        khugepaged_max_ptes_none = HPAGE_PMD_NR - 1;
+       khugepaged_max_ptes_swap = HPAGE_PMD_NR / 8;
        /*
         * hugepages can't be allocated by the buddy allocator
         */
@@ -765,11 +800,6 @@ pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma)
        return pmd;
 }
 
-static inline pmd_t mk_huge_pmd(struct page *page, pgprot_t prot)
-{
-       return pmd_mkhuge(mk_pmd(page, prot));
-}
-
 static inline struct list_head *page_deferred_list(struct page *page)
 {
        /*
@@ -790,26 +820,23 @@ void prep_transhuge_page(struct page *page)
        set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR);
 }
 
-static int __do_huge_pmd_anonymous_page(struct mm_struct *mm,
-                                       struct vm_area_struct *vma,
-                                       unsigned long address, pmd_t *pmd,
-                                       struct page *page, gfp_t gfp,
-                                       unsigned int flags)
+static int __do_huge_pmd_anonymous_page(struct fault_env *fe, struct page *page,
+               gfp_t gfp)
 {
+       struct vm_area_struct *vma = fe->vma;
        struct mem_cgroup *memcg;
        pgtable_t pgtable;
-       spinlock_t *ptl;
-       unsigned long haddr = address & HPAGE_PMD_MASK;
+       unsigned long haddr = fe->address & HPAGE_PMD_MASK;
 
        VM_BUG_ON_PAGE(!PageCompound(page), page);
 
-       if (mem_cgroup_try_charge(page, mm, gfp, &memcg, true)) {
+       if (mem_cgroup_try_charge(page, vma->vm_mm, gfp, &memcg, true)) {
                put_page(page);
                count_vm_event(THP_FAULT_FALLBACK);
                return VM_FAULT_FALLBACK;
        }
 
-       pgtable = pte_alloc_one(mm, haddr);
+       pgtable = pte_alloc_one(vma->vm_mm, haddr);
        if (unlikely(!pgtable)) {
                mem_cgroup_cancel_charge(page, memcg, true);
                put_page(page);
@@ -824,12 +851,12 @@ static int __do_huge_pmd_anonymous_page(struct mm_struct *mm,
         */
        __SetPageUptodate(page);
 
-       ptl = pmd_lock(mm, pmd);
-       if (unlikely(!pmd_none(*pmd))) {
-               spin_unlock(ptl);
+       fe->ptl = pmd_lock(vma->vm_mm, fe->pmd);
+       if (unlikely(!pmd_none(*fe->pmd))) {
+               spin_unlock(fe->ptl);
                mem_cgroup_cancel_charge(page, memcg, true);
                put_page(page);
-               pte_free(mm, pgtable);
+               pte_free(vma->vm_mm, pgtable);
        } else {
                pmd_t entry;
 
@@ -837,12 +864,11 @@ static int __do_huge_pmd_anonymous_page(struct mm_struct *mm,
                if (userfaultfd_missing(vma)) {
                        int ret;
 
-                       spin_unlock(ptl);
+                       spin_unlock(fe->ptl);
                        mem_cgroup_cancel_charge(page, memcg, true);
                        put_page(page);
-                       pte_free(mm, pgtable);
-                       ret = handle_userfault(vma, address, flags,
-                                              VM_UFFD_MISSING);
+                       pte_free(vma->vm_mm, pgtable);
+                       ret = handle_userfault(fe, VM_UFFD_MISSING);
                        VM_BUG_ON(ret & VM_FAULT_FALLBACK);
                        return ret;
                }
@@ -852,11 +878,11 @@ static int __do_huge_pmd_anonymous_page(struct mm_struct *mm,
                page_add_new_anon_rmap(page, vma, haddr, true);
                mem_cgroup_commit_charge(page, memcg, false, true);
                lru_cache_add_active_or_unevictable(page, vma);
-               pgtable_trans_huge_deposit(mm, pmd, pgtable);
-               set_pmd_at(mm, haddr, pmd, entry);
-               add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR);
-               atomic_long_inc(&mm->nr_ptes);
-               spin_unlock(ptl);
+               pgtable_trans_huge_deposit(vma->vm_mm, fe->pmd, pgtable);
+               set_pmd_at(vma->vm_mm, haddr, fe->pmd, entry);
+               add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
+               atomic_long_inc(&vma->vm_mm->nr_ptes);
+               spin_unlock(fe->ptl);
                count_vm_event(THP_FAULT_ALLOC);
        }
 
@@ -906,13 +932,12 @@ static bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm,
        return true;
 }
 
-int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
-                              unsigned long address, pmd_t *pmd,
-                              unsigned int flags)
+int do_huge_pmd_anonymous_page(struct fault_env *fe)
 {
+       struct vm_area_struct *vma = fe->vma;
        gfp_t gfp;
        struct page *page;
-       unsigned long haddr = address & HPAGE_PMD_MASK;
+       unsigned long haddr = fe->address & HPAGE_PMD_MASK;
 
        if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end)
                return VM_FAULT_FALLBACK;
@@ -920,42 +945,40 @@ int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
                return VM_FAULT_OOM;
        if (unlikely(khugepaged_enter(vma, vma->vm_flags)))
                return VM_FAULT_OOM;
-       if (!(flags & FAULT_FLAG_WRITE) && !mm_forbids_zeropage(mm) &&
+       if (!(fe->flags & FAULT_FLAG_WRITE) &&
+                       !mm_forbids_zeropage(vma->vm_mm) &&
                        transparent_hugepage_use_zero_page()) {
-               spinlock_t *ptl;
                pgtable_t pgtable;
                struct page *zero_page;
                bool set;
                int ret;
-               pgtable = pte_alloc_one(mm, haddr);
+               pgtable = pte_alloc_one(vma->vm_mm, haddr);
                if (unlikely(!pgtable))
                        return VM_FAULT_OOM;
                zero_page = get_huge_zero_page();
                if (unlikely(!zero_page)) {
-                       pte_free(mm, pgtable);
+                       pte_free(vma->vm_mm, pgtable);
                        count_vm_event(THP_FAULT_FALLBACK);
                        return VM_FAULT_FALLBACK;
                }
-               ptl = pmd_lock(mm, pmd);
+               fe->ptl = pmd_lock(vma->vm_mm, fe->pmd);
                ret = 0;
                set = false;
-               if (pmd_none(*pmd)) {
+               if (pmd_none(*fe->pmd)) {
                        if (userfaultfd_missing(vma)) {
-                               spin_unlock(ptl);
-                               ret = handle_userfault(vma, address, flags,
-                                                      VM_UFFD_MISSING);
+                               spin_unlock(fe->ptl);
+                               ret = handle_userfault(fe, VM_UFFD_MISSING);
                                VM_BUG_ON(ret & VM_FAULT_FALLBACK);
                        } else {
-                               set_huge_zero_page(pgtable, mm, vma,
-                                                  haddr, pmd,
-                                                  zero_page);
-                               spin_unlock(ptl);
+                               set_huge_zero_page(pgtable, vma->vm_mm, vma,
+                                                  haddr, fe->pmd, zero_page);
+                               spin_unlock(fe->ptl);
                                set = true;
                        }
                } else
-                       spin_unlock(ptl);
+                       spin_unlock(fe->ptl);
                if (!set) {
-                       pte_free(mm, pgtable);
+                       pte_free(vma->vm_mm, pgtable);
                        put_huge_zero_page();
                }
                return ret;
@@ -967,8 +990,7 @@ int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
                return VM_FAULT_FALLBACK;
        }
        prep_transhuge_page(page);
-       return __do_huge_pmd_anonymous_page(mm, vma, address, pmd, page, gfp,
-                                           flags);
+       return __do_huge_pmd_anonymous_page(fe, page, gfp);
 }
 
 static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
@@ -1080,14 +1102,15 @@ int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
        struct page *src_page;
        pmd_t pmd;
        pgtable_t pgtable = NULL;
-       int ret;
+       int ret = -ENOMEM;
 
-       if (!vma_is_dax(vma)) {
-               ret = -ENOMEM;
-               pgtable = pte_alloc_one(dst_mm, addr);
-               if (unlikely(!pgtable))
-                       goto out;
-       }
+       /* Skip if can be re-fill on fault */
+       if (!vma_is_anonymous(vma))
+               return 0;
+
+       pgtable = pte_alloc_one(dst_mm, addr);
+       if (unlikely(!pgtable))
+               goto out;
 
        dst_ptl = pmd_lock(dst_mm, dst_pmd);
        src_ptl = pmd_lockptr(src_mm, src_pmd);
@@ -1095,7 +1118,7 @@ int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 
        ret = -EAGAIN;
        pmd = *src_pmd;
-       if (unlikely(!pmd_trans_huge(pmd) && !pmd_devmap(pmd))) {
+       if (unlikely(!pmd_trans_huge(pmd))) {
                pte_free(dst_mm, pgtable);
                goto out_unlock;
        }
@@ -1118,16 +1141,13 @@ int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
                goto out_unlock;
        }
 
-       if (!vma_is_dax(vma)) {
-               /* thp accounting separate from pmd_devmap accounting */
-               src_page = pmd_page(pmd);
-               VM_BUG_ON_PAGE(!PageHead(src_page), src_page);
-               get_page(src_page);
-               page_dup_rmap(src_page, true);
-               add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
-               atomic_long_inc(&dst_mm->nr_ptes);
-               pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
-       }
+       src_page = pmd_page(pmd);
+       VM_BUG_ON_PAGE(!PageHead(src_page), src_page);
+       get_page(src_page);
+       page_dup_rmap(src_page, true);
+       add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
+       atomic_long_inc(&dst_mm->nr_ptes);
+       pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
 
        pmdp_set_wrprotect(src_mm, addr, src_pmd);
        pmd = pmd_mkold(pmd_wrprotect(pmd));
@@ -1141,38 +1161,31 @@ out:
        return ret;
 }
 
-void huge_pmd_set_accessed(struct mm_struct *mm,
-                          struct vm_area_struct *vma,
-                          unsigned long address,
-                          pmd_t *pmd, pmd_t orig_pmd,
-                          int dirty)
+void huge_pmd_set_accessed(struct fault_env *fe, pmd_t orig_pmd)
 {
-       spinlock_t *ptl;
        pmd_t entry;
        unsigned long haddr;
 
-       ptl = pmd_lock(mm, pmd);
-       if (unlikely(!pmd_same(*pmd, orig_pmd)))
+       fe->ptl = pmd_lock(fe->vma->vm_mm, fe->pmd);
+       if (unlikely(!pmd_same(*fe->pmd, orig_pmd)))
                goto unlock;
 
        entry = pmd_mkyoung(orig_pmd);
-       haddr = address & HPAGE_PMD_MASK;
-       if (pmdp_set_access_flags(vma, haddr, pmd, entry, dirty))
-               update_mmu_cache_pmd(vma, address, pmd);
+       haddr = fe->address & HPAGE_PMD_MASK;
+       if (pmdp_set_access_flags(fe->vma, haddr, fe->pmd, entry,
+                               fe->flags & FAULT_FLAG_WRITE))
+               update_mmu_cache_pmd(fe->vma, fe->address, fe->pmd);
 
 unlock:
-       spin_unlock(ptl);
+       spin_unlock(fe->ptl);
 }
 
-static int do_huge_pmd_wp_page_fallback(struct mm_struct *mm,
-                                       struct vm_area_struct *vma,
-                                       unsigned long address,
-                                       pmd_t *pmd, pmd_t orig_pmd,
-                                       struct page *page,
-                                       unsigned long haddr)
+static int do_huge_pmd_wp_page_fallback(struct fault_env *fe, pmd_t orig_pmd,
+               struct page *page)
 {
+       struct vm_area_struct *vma = fe->vma;
+       unsigned long haddr = fe->address & HPAGE_PMD_MASK;
        struct mem_cgroup *memcg;
-       spinlock_t *ptl;
        pgtable_t pgtable;
        pmd_t _pmd;
        int ret = 0, i;
@@ -1189,11 +1202,11 @@ static int do_huge_pmd_wp_page_fallback(struct mm_struct *mm,
 
        for (i = 0; i < HPAGE_PMD_NR; i++) {
                pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE |
-                                              __GFP_OTHER_NODE,
-                                              vma, address, page_to_nid(page));
+                                              __GFP_OTHER_NODE, vma,
+                                              fe->address, page_to_nid(page));
                if (unlikely(!pages[i] ||
-                            mem_cgroup_try_charge(pages[i], mm, GFP_KERNEL,
-                                                  &memcg, false))) {
+                            mem_cgroup_try_charge(pages[i], vma->vm_mm,
+                                    GFP_KERNEL, &memcg, false))) {
                        if (pages[i])
                                put_page(pages[i]);
                        while (--i >= 0) {
@@ -1219,41 +1232,41 @@ static int do_huge_pmd_wp_page_fallback(struct mm_struct *mm,
 
        mmun_start = haddr;
        mmun_end   = haddr + HPAGE_PMD_SIZE;
-       mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
+       mmu_notifier_invalidate_range_start(vma->vm_mm, mmun_start, mmun_end);
 
-       ptl = pmd_lock(mm, pmd);
-       if (unlikely(!pmd_same(*pmd, orig_pmd)))
+       fe->ptl = pmd_lock(vma->vm_mm, fe->pmd);
+       if (unlikely(!pmd_same(*fe->pmd, orig_pmd)))
                goto out_free_pages;
        VM_BUG_ON_PAGE(!PageHead(page), page);
 
-       pmdp_huge_clear_flush_notify(vma, haddr, pmd);
+       pmdp_huge_clear_flush_notify(vma, haddr, fe->pmd);
        /* leave pmd empty until pte is filled */
 
-       pgtable = pgtable_trans_huge_withdraw(mm, pmd);
-       pmd_populate(mm, &_pmd, pgtable);
+       pgtable = pgtable_trans_huge_withdraw(vma->vm_mm, fe->pmd);
+       pmd_populate(vma->vm_mm, &_pmd, pgtable);
 
        for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
-               pte_t *pte, entry;
+               pte_t entry;
                entry = mk_pte(pages[i], vma->vm_page_prot);
                entry = maybe_mkwrite(pte_mkdirty(entry), vma);
                memcg = (void *)page_private(pages[i]);
                set_page_private(pages[i], 0);
-               page_add_new_anon_rmap(pages[i], vma, haddr, false);
+               page_add_new_anon_rmap(pages[i], fe->vma, haddr, false);
                mem_cgroup_commit_charge(pages[i], memcg, false, false);
                lru_cache_add_active_or_unevictable(pages[i], vma);
-               pte = pte_offset_map(&_pmd, haddr);
-               VM_BUG_ON(!pte_none(*pte));
-               set_pte_at(mm, haddr, pte, entry);
-               pte_unmap(pte);
+               fe->pte = pte_offset_map(&_pmd, haddr);
+               VM_BUG_ON(!pte_none(*fe->pte));
+               set_pte_at(vma->vm_mm, haddr, fe->pte, entry);
+               pte_unmap(fe->pte);
        }
        kfree(pages);
 
        smp_wmb(); /* make pte visible before pmd */
-       pmd_populate(mm, pmd, pgtable);
+       pmd_populate(vma->vm_mm, fe->pmd, pgtable);
        page_remove_rmap(page, true);
-       spin_unlock(ptl);
+       spin_unlock(fe->ptl);
 
-       mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
+       mmu_notifier_invalidate_range_end(vma->vm_mm, mmun_start, mmun_end);
 
        ret |= VM_FAULT_WRITE;
        put_page(page);
@@ -1262,8 +1275,8 @@ out:
        return ret;
 
 out_free_pages:
-       spin_unlock(ptl);
-       mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
+       spin_unlock(fe->ptl);
+       mmu_notifier_invalidate_range_end(vma->vm_mm, mmun_start, mmun_end);
        for (i = 0; i < HPAGE_PMD_NR; i++) {
                memcg = (void *)page_private(pages[i]);
                set_page_private(pages[i], 0);
@@ -1274,25 +1287,23 @@ out_free_pages:
        goto out;
 }
 
-int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
-                       unsigned long address, pmd_t *pmd, pmd_t orig_pmd)
+int do_huge_pmd_wp_page(struct fault_env *fe, pmd_t orig_pmd)
 {
-       spinlock_t *ptl;
-       int ret = 0;
+       struct vm_area_struct *vma = fe->vma;
        struct page *page = NULL, *new_page;
        struct mem_cgroup *memcg;
-       unsigned long haddr;
+       unsigned long haddr = fe->address & HPAGE_PMD_MASK;
        unsigned long mmun_start;       /* For mmu_notifiers */
        unsigned long mmun_end;         /* For mmu_notifiers */
        gfp_t huge_gfp;                 /* for allocation and charge */
+       int ret = 0;
 
-       ptl = pmd_lockptr(mm, pmd);
+       fe->ptl = pmd_lockptr(vma->vm_mm, fe->pmd);
        VM_BUG_ON_VMA(!vma->anon_vma, vma);
-       haddr = address & HPAGE_PMD_MASK;
        if (is_huge_zero_pmd(orig_pmd))
                goto alloc;
-       spin_lock(ptl);
-       if (unlikely(!pmd_same(*pmd, orig_pmd)))
+       spin_lock(fe->ptl);
+       if (unlikely(!pmd_same(*fe->pmd, orig_pmd)))
                goto out_unlock;
 
        page = pmd_page(orig_pmd);
@@ -1305,13 +1316,13 @@ int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
                pmd_t entry;
                entry = pmd_mkyoung(orig_pmd);
                entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
-               if (pmdp_set_access_flags(vma, haddr, pmd, entry,  1))
-                       update_mmu_cache_pmd(vma, address, pmd);
+               if (pmdp_set_access_flags(vma, haddr, fe->pmd, entry,  1))
+                       update_mmu_cache_pmd(vma, fe->address, fe->pmd);
                ret |= VM_FAULT_WRITE;
                goto out_unlock;
        }
        get_page(page);
-       spin_unlock(ptl);
+       spin_unlock(fe->ptl);
 alloc:
        if (transparent_hugepage_enabled(vma) &&
            !transparent_hugepage_debug_cow()) {
@@ -1324,13 +1335,12 @@ alloc:
                prep_transhuge_page(new_page);
        } else {
                if (!page) {
-                       split_huge_pmd(vma, pmd, address);
+                       split_huge_pmd(vma, fe->pmd, fe->address);
                        ret |= VM_FAULT_FALLBACK;
                } else {
-                       ret = do_huge_pmd_wp_page_fallback(mm, vma, address,
-                                       pmd, orig_pmd, page, haddr);
+                       ret = do_huge_pmd_wp_page_fallback(fe, orig_pmd, page);
                        if (ret & VM_FAULT_OOM) {
-                               split_huge_pmd(vma, pmd, address);
+                               split_huge_pmd(vma, fe->pmd, fe->address);
                                ret |= VM_FAULT_FALLBACK;
                        }
                        put_page(page);
@@ -1339,14 +1349,12 @@ alloc:
                goto out;
        }
 
-       if (unlikely(mem_cgroup_try_charge(new_page, mm, huge_gfp, &memcg,
-                                          true))) {
+       if (unlikely(mem_cgroup_try_charge(new_page, vma->vm_mm,
+                                       huge_gfp, &memcg, true))) {
                put_page(new_page);
-               if (page) {
-                       split_huge_pmd(vma, pmd, address);
+               split_huge_pmd(vma, fe->pmd, fe->address);
+               if (page)
                        put_page(page);
-               } else
-                       split_huge_pmd(vma, pmd, address);
                ret |= VM_FAULT_FALLBACK;
                count_vm_event(THP_FAULT_FALLBACK);
                goto out;
@@ -1362,13 +1370,13 @@ alloc:
 
        mmun_start = haddr;
        mmun_end   = haddr + HPAGE_PMD_SIZE;
-       mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
+       mmu_notifier_invalidate_range_start(vma->vm_mm, mmun_start, mmun_end);
 
-       spin_lock(ptl);
+       spin_lock(fe->ptl);
        if (page)
                put_page(page);
-       if (unlikely(!pmd_same(*pmd, orig_pmd))) {
-               spin_unlock(ptl);
+       if (unlikely(!pmd_same(*fe->pmd, orig_pmd))) {
+               spin_unlock(fe->ptl);
                mem_cgroup_cancel_charge(new_page, memcg, true);
                put_page(new_page);
                goto out_mn;
@@ -1376,14 +1384,14 @@ alloc:
                pmd_t entry;
                entry = mk_huge_pmd(new_page, vma->vm_page_prot);
                entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
-               pmdp_huge_clear_flush_notify(vma, haddr, pmd);
+               pmdp_huge_clear_flush_notify(vma, haddr, fe->pmd);
                page_add_new_anon_rmap(new_page, vma, haddr, true);
                mem_cgroup_commit_charge(new_page, memcg, false, true);
                lru_cache_add_active_or_unevictable(new_page, vma);
-               set_pmd_at(mm, haddr, pmd, entry);
-               update_mmu_cache_pmd(vma, address, pmd);
+               set_pmd_at(vma->vm_mm, haddr, fe->pmd, entry);
+               update_mmu_cache_pmd(vma, fe->address, fe->pmd);
                if (!page) {
-                       add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR);
+                       add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
                        put_huge_zero_page();
                } else {
                        VM_BUG_ON_PAGE(!PageHead(page), page);
@@ -1392,13 +1400,13 @@ alloc:
                }
                ret |= VM_FAULT_WRITE;
        }
-       spin_unlock(ptl);
+       spin_unlock(fe->ptl);
 out_mn:
-       mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
+       mmu_notifier_invalidate_range_end(vma->vm_mm, mmun_start, mmun_end);
 out:
        return ret;
 out_unlock:
-       spin_unlock(ptl);
+       spin_unlock(fe->ptl);
        return ret;
 }
 
@@ -1432,6 +1440,8 @@ struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
                 * We don't mlock() pte-mapped THPs. This way we can avoid
                 * leaking mlocked pages into non-VM_LOCKED VMAs.
                 *
+                * For anon THP:
+                *
                 * In most cases the pmd is the only mapping of the page as we
                 * break COW for the mlock() -- see gup_flags |= FOLL_WRITE for
                 * writable private mappings in populate_vma_page_range().
@@ -1439,15 +1449,26 @@ struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
                 * The only scenario when we have the page shared here is if we
                 * mlocking read-only mapping shared over fork(). We skip
                 * mlocking such pages.
+                *
+                * For file THP:
+                *
+                * We can expect PageDoubleMap() to be stable under page lock:
+                * for file pages we set it in page_add_file_rmap(), which
+                * requires page to be locked.
                 */
-               if (compound_mapcount(page) == 1 && !PageDoubleMap(page) &&
-                               page->mapping && trylock_page(page)) {
-                       lru_add_drain();
-                       if (page->mapping)
-                               mlock_vma_page(page);
-                       unlock_page(page);
-               }
+
+               if (PageAnon(page) && compound_mapcount(page) != 1)
+                       goto skip_mlock;
+               if (PageDoubleMap(page) || !page->mapping)
+                       goto skip_mlock;
+               if (!trylock_page(page))
+                       goto skip_mlock;
+               lru_add_drain();
+               if (page->mapping && !PageDoubleMap(page))
+                       mlock_vma_page(page);
+               unlock_page(page);
        }
+skip_mlock:
        page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
        VM_BUG_ON_PAGE(!PageCompound(page), page);
        if (flags & FOLL_GET)
@@ -1458,13 +1479,12 @@ out:
 }
 
 /* NUMA hinting page fault entry point for trans huge pmds */
-int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
-                               unsigned long addr, pmd_t pmd, pmd_t *pmdp)
+int do_huge_pmd_numa_page(struct fault_env *fe, pmd_t pmd)
 {
-       spinlock_t *ptl;
+       struct vm_area_struct *vma = fe->vma;
        struct anon_vma *anon_vma = NULL;
        struct page *page;
-       unsigned long haddr = addr & HPAGE_PMD_MASK;
+       unsigned long haddr = fe->address & HPAGE_PMD_MASK;
        int page_nid = -1, this_nid = numa_node_id();
        int target_nid, last_cpupid = -1;
        bool page_locked;
@@ -1475,8 +1495,8 @@ int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
        /* A PROT_NONE fault should not end up here */
        BUG_ON(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)));
 
-       ptl = pmd_lock(mm, pmdp);
-       if (unlikely(!pmd_same(pmd, *pmdp)))
+       fe->ptl = pmd_lock(vma->vm_mm, fe->pmd);
+       if (unlikely(!pmd_same(pmd, *fe->pmd)))
                goto out_unlock;
 
        /*
@@ -1484,9 +1504,9 @@ int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
         * without disrupting NUMA hinting information. Do not relock and
         * check_same as the page may no longer be mapped.
         */
-       if (unlikely(pmd_trans_migrating(*pmdp))) {
-               page = pmd_page(*pmdp);
-               spin_unlock(ptl);
+       if (unlikely(pmd_trans_migrating(*fe->pmd))) {
+               page = pmd_page(*fe->pmd);
+               spin_unlock(fe->ptl);
                wait_on_page_locked(page);
                goto out;
        }
@@ -1519,7 +1539,7 @@ int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
 
        /* Migration could have started since the pmd_trans_migrating check */
        if (!page_locked) {
-               spin_unlock(ptl);
+               spin_unlock(fe->ptl);
                wait_on_page_locked(page);
                page_nid = -1;
                goto out;
@@ -1530,12 +1550,12 @@ int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
         * to serialises splits
         */
        get_page(page);
-       spin_unlock(ptl);
+       spin_unlock(fe->ptl);
        anon_vma = page_lock_anon_vma_read(page);
 
        /* Confirm the PMD did not change while page_table_lock was released */
-       spin_lock(ptl);
-       if (unlikely(!pmd_same(pmd, *pmdp))) {
+       spin_lock(fe->ptl);
+       if (unlikely(!pmd_same(pmd, *fe->pmd))) {
                unlock_page(page);
                put_page(page);
                page_nid = -1;
@@ -1553,9 +1573,9 @@ int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
         * Migrate the THP to the requested node, returns with page unlocked
         * and access rights restored.
         */
-       spin_unlock(ptl);
-       migrated = migrate_misplaced_transhuge_page(mm, vma,
-                               pmdp, pmd, addr, page, target_nid);
+       spin_unlock(fe->ptl);
+       migrated = migrate_misplaced_transhuge_page(vma->vm_mm, vma,
+                               fe->pmd, pmd, fe->address, page, target_nid);
        if (migrated) {
                flags |= TNF_MIGRATED;
                page_nid = target_nid;
@@ -1570,18 +1590,18 @@ clear_pmdnuma:
        pmd = pmd_mkyoung(pmd);
        if (was_writable)
                pmd = pmd_mkwrite(pmd);
-       set_pmd_at(mm, haddr, pmdp, pmd);
-       update_mmu_cache_pmd(vma, addr, pmdp);
+       set_pmd_at(vma->vm_mm, haddr, fe->pmd, pmd);
+       update_mmu_cache_pmd(vma, fe->address, fe->pmd);
        unlock_page(page);
 out_unlock:
-       spin_unlock(ptl);
+       spin_unlock(fe->ptl);
 
 out:
        if (anon_vma)
                page_unlock_anon_vma_read(anon_vma);
 
        if (page_nid != -1)
-               task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR, flags);
+               task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR, fe->flags);
 
        return 0;
 }
@@ -1624,14 +1644,9 @@ int madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
        if (next - addr != HPAGE_PMD_SIZE) {
                get_page(page);
                spin_unlock(ptl);
-               if (split_huge_page(page)) {
-                       put_page(page);
-                       unlock_page(page);
-                       goto out_unlocked;
-               }
+               split_huge_page(page);
                put_page(page);
                unlock_page(page);
-               ret = 1;
                goto out_unlocked;
        }
 
@@ -1689,12 +1704,18 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
                struct page *page = pmd_page(orig_pmd);
                page_remove_rmap(page, true);
                VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
-               add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
                VM_BUG_ON_PAGE(!PageHead(page), page);
-               pte_free(tlb->mm, pgtable_trans_huge_withdraw(tlb->mm, pmd));
-               atomic_long_dec(&tlb->mm->nr_ptes);
+               if (PageAnon(page)) {
+                       pgtable_t pgtable;
+                       pgtable = pgtable_trans_huge_withdraw(tlb->mm, pmd);
+                       pte_free(tlb->mm, pgtable);
+                       atomic_long_dec(&tlb->mm->nr_ptes);
+                       add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
+               } else {
+                       add_mm_counter(tlb->mm, MM_FILEPAGES, -HPAGE_PMD_NR);
+               }
                spin_unlock(ptl);
-               tlb_remove_page(tlb, page);
+               tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE);
        }
        return 1;
 }
@@ -1784,7 +1805,8 @@ int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
                                entry = pmd_mkwrite(entry);
                        ret = HPAGE_PMD_NR;
                        set_pmd_at(mm, addr, pmd, entry);
-                       BUG_ON(!preserve_write && pmd_write(entry));
+                       BUG_ON(vma_is_anonymous(vma) && !preserve_write &&
+                                       pmd_write(entry));
                }
                spin_unlock(ptl);
        }
@@ -2347,6 +2369,86 @@ static bool hugepage_vma_check(struct vm_area_struct *vma)
        return !(vma->vm_flags & VM_NO_THP);
 }
 
+/*
+ * If mmap_sem temporarily dropped, revalidate vma
+ * before taking mmap_sem.
+ * Return 0 if succeeds, otherwise return none-zero
+ * value (scan code).
+ */
+
+static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address)
+{
+       struct vm_area_struct *vma;
+       unsigned long hstart, hend;
+
+       if (unlikely(khugepaged_test_exit(mm)))
+               return SCAN_ANY_PROCESS;
+
+       vma = find_vma(mm, address);
+       if (!vma)
+               return SCAN_VMA_NULL;
+
+       hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
+       hend = vma->vm_end & HPAGE_PMD_MASK;
+       if (address < hstart || address + HPAGE_PMD_SIZE > hend)
+               return SCAN_ADDRESS_RANGE;
+       if (!hugepage_vma_check(vma))
+               return SCAN_VMA_CHECK;
+       return 0;
+}
+
+/*
+ * Bring missing pages in from swap, to complete THP collapse.
+ * Only done if khugepaged_scan_pmd believes it is worthwhile.
+ *
+ * Called and returns without pte mapped or spinlocks held,
+ * but with mmap_sem held to protect against vma changes.
+ */
+
+static bool __collapse_huge_page_swapin(struct mm_struct *mm,
+                                       struct vm_area_struct *vma,
+                                       unsigned long address, pmd_t *pmd)
+{
+       pte_t pteval;
+       int swapped_in = 0, ret = 0;
+       struct fault_env fe = {
+               .vma = vma,
+               .address = address,
+               .flags = FAULT_FLAG_ALLOW_RETRY,
+               .pmd = pmd,
+       };
+
+       fe.pte = pte_offset_map(pmd, address);
+       for (; fe.address < address + HPAGE_PMD_NR*PAGE_SIZE;
+                       fe.pte++, fe.address += PAGE_SIZE) {
+               pteval = *fe.pte;
+               if (!is_swap_pte(pteval))
+                       continue;
+               swapped_in++;
+               ret = do_swap_page(&fe, pteval);
+               /* do_swap_page returns VM_FAULT_RETRY with released mmap_sem */
+               if (ret & VM_FAULT_RETRY) {
+                       down_read(&mm->mmap_sem);
+                       /* vma is no longer available, don't continue to swapin */
+                       if (hugepage_vma_revalidate(mm, address))
+                               return false;
+                       /* check if the pmd is still valid */
+                       if (mm_find_pmd(mm, address) != pmd)
+                               return false;
+               }
+               if (ret & VM_FAULT_ERROR) {
+                       trace_mm_collapse_huge_page_swapin(mm, swapped_in, 0);
+                       return false;
+               }
+               /* pte is unmapped now, we need to map it */
+               fe.pte = pte_offset_map(pmd, fe.address);
+       }
+       fe.pte--;
+       pte_unmap(fe.pte);
+       trace_mm_collapse_huge_page_swapin(mm, swapped_in, 1);
+       return true;
+}
+
 static void collapse_huge_page(struct mm_struct *mm,
                                   unsigned long address,
                                   struct page **hpage,
@@ -2359,7 +2461,6 @@ static void collapse_huge_page(struct mm_struct *mm,
        struct page *new_page;
        spinlock_t *pmd_ptl, *pte_ptl;
        int isolated = 0, result = 0;
-       unsigned long hstart, hend;
        struct mem_cgroup *memcg;
        unsigned long mmun_start;       /* For mmu_notifiers */
        unsigned long mmun_end;         /* For mmu_notifiers */
@@ -2382,37 +2483,46 @@ static void collapse_huge_page(struct mm_struct *mm,
                goto out_nolock;
        }
 
+       down_read(&mm->mmap_sem);
+       result = hugepage_vma_revalidate(mm, address);
+       if (result) {
+               mem_cgroup_cancel_charge(new_page, memcg, true);
+               up_read(&mm->mmap_sem);
+               goto out_nolock;
+       }
+
+       pmd = mm_find_pmd(mm, address);
+       if (!pmd) {
+               result = SCAN_PMD_NULL;
+               mem_cgroup_cancel_charge(new_page, memcg, true);
+               up_read(&mm->mmap_sem);
+               goto out_nolock;
+       }
+
+       /*
+        * __collapse_huge_page_swapin always returns with mmap_sem locked.
+        * If it fails, release mmap_sem and jump directly out.
+        * Continuing to collapse causes inconsistency.
+        */
+       if (!__collapse_huge_page_swapin(mm, vma, address, pmd)) {
+               mem_cgroup_cancel_charge(new_page, memcg, true);
+               up_read(&mm->mmap_sem);
+               goto out_nolock;
+       }
+
+       up_read(&mm->mmap_sem);
        /*
         * Prevent all access to pagetables with the exception of
-        * gup_fast later hanlded by the ptep_clear_flush and the VM
+        * gup_fast later handled by the ptep_clear_flush and the VM
         * handled by the anon_vma lock + PG_lock.
         */
        down_write(&mm->mmap_sem);
-       if (unlikely(khugepaged_test_exit(mm))) {
-               result = SCAN_ANY_PROCESS;
-               goto out;
-       }
-
-       vma = find_vma(mm, address);
-       if (!vma) {
-               result = SCAN_VMA_NULL;
-               goto out;
-       }
-       hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
-       hend = vma->vm_end & HPAGE_PMD_MASK;
-       if (address < hstart || address + HPAGE_PMD_SIZE > hend) {
-               result = SCAN_ADDRESS_RANGE;
+       result = hugepage_vma_revalidate(mm, address);
+       if (result)
                goto out;
-       }
-       if (!hugepage_vma_check(vma)) {
-               result = SCAN_VMA_CHECK;
-               goto out;
-       }
-       pmd = mm_find_pmd(mm, address);
-       if (!pmd) {
-               result = SCAN_PMD_NULL;
+       /* check if the pmd is still valid */
+       if (mm_find_pmd(mm, address) != pmd)
                goto out;
-       }
 
        anon_vma_lock_write(vma->anon_vma);
 
@@ -2490,9 +2600,6 @@ static void collapse_huge_page(struct mm_struct *mm,
        result = SCAN_SUCCEED;
 out_up_write:
        up_write(&mm->mmap_sem);
-       trace_mm_collapse_huge_page(mm, isolated, result);
-       return;
-
 out_nolock:
        trace_mm_collapse_huge_page(mm, isolated, result);
        return;
@@ -2512,7 +2619,7 @@ static int khugepaged_scan_pmd(struct mm_struct *mm,
        struct page *page = NULL;
        unsigned long _address;
        spinlock_t *ptl;
-       int node = NUMA_NO_NODE;
+       int node = NUMA_NO_NODE, unmapped = 0;
        bool writable = false, referenced = false;
 
        VM_BUG_ON(address & ~HPAGE_PMD_MASK);
@@ -2528,6 +2635,14 @@ static int khugepaged_scan_pmd(struct mm_struct *mm,
        for (_address = address, _pte = pte; _pte < pte+HPAGE_PMD_NR;
             _pte++, _address += PAGE_SIZE) {
                pte_t pteval = *_pte;
+               if (is_swap_pte(pteval)) {
+                       if (++unmapped <= khugepaged_max_ptes_swap) {
+                               continue;
+                       } else {
+                               result = SCAN_EXCEED_SWAP_PTE;
+                               goto out_unmap;
+                       }
+               }
                if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) {
                        if (!userfaultfd_armed(vma) &&
                            ++none_or_zero <= khugepaged_max_ptes_none) {
@@ -2614,7 +2729,7 @@ out_unmap:
        }
 out:
        trace_mm_khugepaged_scan_pmd(mm, page, writable, referenced,
-                                    none_or_zero, result);
+                                    none_or_zero, result, unmapped);
        return ret;
 }
 
@@ -2888,10 +3003,18 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
 
        count_vm_event(THP_SPLIT_PMD);
 
-       if (vma_is_dax(vma)) {
-               pmd_t _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd);
+       if (!vma_is_anonymous(vma)) {
+               _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd);
                if (is_huge_zero_pmd(_pmd))
                        put_huge_zero_page();
+               if (vma_is_dax(vma))
+                       return;
+               page = pmd_page(_pmd);
+               if (!PageReferenced(page) && pmd_young(_pmd))
+                       SetPageReferenced(page);
+               page_remove_rmap(page, true);
+               put_page(page);
+               add_mm_counter(mm, MM_FILEPAGES, -HPAGE_PMD_NR);
                return;
        } else if (is_huge_zero_pmd(*pmd)) {
                return __split_huge_zero_page_pmd(vma, haddr, pmd);
@@ -2947,7 +3070,7 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
 
        if (atomic_add_negative(-1, compound_mapcount_ptr(page))) {
                /* Last compound_mapcount is gone. */
-               __dec_zone_page_state(page, NR_ANON_TRANSPARENT_HUGEPAGES);
+               __dec_zone_page_state(page, NR_ANON_THPS);
                if (TestClearPageDoubleMap(page)) {
                        /* No need in mapcount reference anymore */
                        for (i = 0; i < HPAGE_PMD_NR; i++)
@@ -2989,7 +3112,7 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
 }
 
 void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
-               unsigned long address, bool freeze)
+               unsigned long address, bool freeze, struct page *page)
 {
        spinlock_t *ptl;
        struct mm_struct *mm = vma->vm_mm;
@@ -2997,8 +3120,17 @@ void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
 
        mmu_notifier_invalidate_range_start(mm, haddr, haddr + HPAGE_PMD_SIZE);
        ptl = pmd_lock(mm, pmd);
+
+       /*
+        * If caller asks to setup a migration entries, we need a page to check
+        * pmd against. Otherwise we can end up replacing wrong page.
+        */
+       VM_BUG_ON(freeze && !page);
+       if (page && page != pmd_page(*pmd))
+               goto out;
+
        if (pmd_trans_huge(*pmd)) {
-               struct page *page = pmd_page(*pmd);
+               page = pmd_page(*pmd);
                if (PageMlocked(page))
                        clear_page_mlock(page);
        } else if (!pmd_devmap(*pmd))
@@ -3025,24 +3157,8 @@ void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address,
                return;
 
        pmd = pmd_offset(pud, address);
-       if (!pmd_present(*pmd) || (!pmd_trans_huge(*pmd) && !pmd_devmap(*pmd)))
-               return;
 
-       /*
-        * If caller asks to setup a migration entries, we need a page to check
-        * pmd against. Otherwise we can end up replacing wrong page.
-        */
-       VM_BUG_ON(freeze && !page);
-       if (page && page != pmd_page(*pmd))
-               return;
-
-       /*
-        * Caller holds the mmap_sem write mode or the anon_vma lock,
-        * so a huge pmd cannot materialize from under us (khugepaged
-        * holds both the mmap_sem write mode and the anon_vma lock
-        * write mode).
-        */
-       __split_huge_pmd(vma, pmd, address, freeze);
+       __split_huge_pmd(vma, pmd, address, freeze, page);
 }
 
 void vma_adjust_trans_huge(struct vm_area_struct *vma,
@@ -3088,12 +3204,15 @@ void vma_adjust_trans_huge(struct vm_area_struct *vma,
 
 static void freeze_page(struct page *page)
 {
-       enum ttu_flags ttu_flags = TTU_MIGRATION | TTU_IGNORE_MLOCK |
-               TTU_IGNORE_ACCESS | TTU_RMAP_LOCKED;
+       enum ttu_flags ttu_flags = TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS |
+               TTU_RMAP_LOCKED;
        int i, ret;
 
        VM_BUG_ON_PAGE(!PageHead(page), page);
 
+       if (PageAnon(page))
+               ttu_flags |= TTU_MIGRATION;
+
        /* We only need TTU_SPLIT_HUGE_PMD once */
        ret = try_to_unmap(page, ttu_flags | TTU_SPLIT_HUGE_PMD);
        for (i = 1; !ret && i < HPAGE_PMD_NR; i++) {
@@ -3103,7 +3222,7 @@ static void freeze_page(struct page *page)
 
                ret = try_to_unmap(page + i, ttu_flags);
        }
-       VM_BUG_ON(ret);
+       VM_BUG_ON_PAGE(ret, page + i - 1);
 }
 
 static void unfreeze_page(struct page *page)
@@ -3125,15 +3244,20 @@ static void __split_huge_page_tail(struct page *head, int tail,
        /*
         * tail_page->_refcount is zero and not changing from under us. But
         * get_page_unless_zero() may be running from under us on the
-        * tail_page. If we used atomic_set() below instead of atomic_inc(), we
-        * would then run atomic_set() concurrently with
+        * tail_page. If we used atomic_set() below instead of atomic_inc() or
+        * atomic_add(), we would then run atomic_set() concurrently with
         * get_page_unless_zero(), and atomic_set() is implemented in C not
         * using locked ops. spin_unlock on x86 sometime uses locked ops
         * because of PPro errata 66, 92, so unless somebody can guarantee
         * atomic_set() here would be safe on all archs (and not only on x86),
-        * it's safer to use atomic_inc().
+        * it's safer to use atomic_inc()/atomic_add().
         */
-       page_ref_inc(page_tail);
+       if (PageAnon(head)) {
+               page_ref_inc(page_tail);
+       } else {
+               /* Additional pin to radix tree */
+               page_ref_add(page_tail, 2);
+       }
 
        page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
        page_tail->flags |= (head->flags &
@@ -3169,25 +3293,46 @@ static void __split_huge_page_tail(struct page *head, int tail,
        lru_add_page_tail(head, page_tail, lruvec, list);
 }
 
-static void __split_huge_page(struct page *page, struct list_head *list)
+static void __split_huge_page(struct page *page, struct list_head *list,
+               unsigned long flags)
 {
        struct page *head = compound_head(page);
        struct zone *zone = page_zone(head);
        struct lruvec *lruvec;
+       pgoff_t end = -1;
        int i;
 
-       /* prevent PageLRU to go away from under us, and freeze lru stats */
-       spin_lock_irq(&zone->lru_lock);
        lruvec = mem_cgroup_page_lruvec(head, zone);
 
        /* complete memcg works before add pages to LRU */
        mem_cgroup_split_huge_fixup(head);
 
-       for (i = HPAGE_PMD_NR - 1; i >= 1; i--)
+       if (!PageAnon(page))
+               end = DIV_ROUND_UP(i_size_read(head->mapping->host), PAGE_SIZE);
+
+       for (i = HPAGE_PMD_NR - 1; i >= 1; i--) {
                __split_huge_page_tail(head, i, lruvec, list);
+               /* Some pages can be beyond i_size: drop them from page cache */
+               if (head[i].index >= end) {
+                       __ClearPageDirty(head + i);
+                       __delete_from_page_cache(head + i, NULL);
+                       if (IS_ENABLED(CONFIG_SHMEM) && PageSwapBacked(head))
+                               shmem_uncharge(head->mapping->host, 1);
+                       put_page(head + i);
+               }
+       }
 
        ClearPageCompound(head);
-       spin_unlock_irq(&zone->lru_lock);
+       /* See comment in __split_huge_page_tail() */
+       if (PageAnon(head)) {
+               page_ref_inc(head);
+       } else {
+               /* Additional pin to radix tree */
+               page_ref_add(head, 2);
+               spin_unlock(&head->mapping->tree_lock);
+       }
+
+       spin_unlock_irqrestore(&page_zone(head)->lru_lock, flags);
 
        unfreeze_page(head);
 
@@ -3210,18 +3355,22 @@ static void __split_huge_page(struct page *page, struct list_head *list)
 
 int total_mapcount(struct page *page)
 {
-       int i, ret;
+       int i, compound, ret;
 
        VM_BUG_ON_PAGE(PageTail(page), page);
 
        if (likely(!PageCompound(page)))
                return atomic_read(&page->_mapcount) + 1;
 
-       ret = compound_mapcount(page);
+       compound = compound_mapcount(page);
        if (PageHuge(page))
-               return ret;
+               return compound;
+       ret = compound;
        for (i = 0; i < HPAGE_PMD_NR; i++)
                ret += atomic_read(&page[i]._mapcount) + 1;
+       /* File pages has compound_mapcount included in _mapcount */
+       if (!PageAnon(page))
+               return ret - compound * HPAGE_PMD_NR;
        if (PageDoubleMap(page))
                ret -= HPAGE_PMD_NR;
        return ret;
@@ -3308,36 +3457,54 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
 {
        struct page *head = compound_head(page);
        struct pglist_data *pgdata = NODE_DATA(page_to_nid(head));
-       struct anon_vma *anon_vma;
-       int count, mapcount, ret;
+       struct anon_vma *anon_vma = NULL;
+       struct address_space *mapping = NULL;
+       int count, mapcount, extra_pins, ret;
        bool mlocked;
        unsigned long flags;
 
        VM_BUG_ON_PAGE(is_huge_zero_page(page), page);
-       VM_BUG_ON_PAGE(!PageAnon(page), page);
        VM_BUG_ON_PAGE(!PageLocked(page), page);
        VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
        VM_BUG_ON_PAGE(!PageCompound(page), page);
 
-       /*
-        * The caller does not necessarily hold an mmap_sem that would prevent
-        * the anon_vma disappearing so we first we take a reference to it
-        * and then lock the anon_vma for write. This is similar to
-        * page_lock_anon_vma_read except the write lock is taken to serialise
-        * against parallel split or collapse operations.
-        */
-       anon_vma = page_get_anon_vma(head);
-       if (!anon_vma) {
-               ret = -EBUSY;
-               goto out;
+       if (PageAnon(head)) {
+               /*
+                * The caller does not necessarily hold an mmap_sem that would
+                * prevent the anon_vma disappearing so we first we take a
+                * reference to it and then lock the anon_vma for write. This
+                * is similar to page_lock_anon_vma_read except the write lock
+                * is taken to serialise against parallel split or collapse
+                * operations.
+                */
+               anon_vma = page_get_anon_vma(head);
+               if (!anon_vma) {
+                       ret = -EBUSY;
+                       goto out;
+               }
+               extra_pins = 0;
+               mapping = NULL;
+               anon_vma_lock_write(anon_vma);
+       } else {
+               mapping = head->mapping;
+
+               /* Truncated ? */
+               if (!mapping) {
+                       ret = -EBUSY;
+                       goto out;
+               }
+
+               /* Addidional pins from radix tree */
+               extra_pins = HPAGE_PMD_NR;
+               anon_vma = NULL;
+               i_mmap_lock_read(mapping);
        }
-       anon_vma_lock_write(anon_vma);
 
        /*
         * Racy check if we can split the page, before freeze_page() will
         * split PMDs
         */
-       if (total_mapcount(head) != page_count(head) - 1) {
+       if (total_mapcount(head) != page_count(head) - extra_pins - 1) {
                ret = -EBUSY;
                goto out_unlock;
        }
@@ -3350,35 +3517,62 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
        if (mlocked)
                lru_add_drain();
 
+       /* prevent PageLRU to go away from under us, and freeze lru stats */
+       spin_lock_irqsave(&page_zone(head)->lru_lock, flags);
+
+       if (mapping) {
+               void **pslot;
+
+               spin_lock(&mapping->tree_lock);
+               pslot = radix_tree_lookup_slot(&mapping->page_tree,
+                               page_index(head));
+               /*
+                * Check if the head page is present in radix tree.
+                * We assume all tail are present too, if head is there.
+                */
+               if (radix_tree_deref_slot_protected(pslot,
+                                       &mapping->tree_lock) != head)
+                       goto fail;
+       }
+
        /* Prevent deferred_split_scan() touching ->_refcount */
-       spin_lock_irqsave(&pgdata->split_queue_lock, flags);
+       spin_lock(&pgdata->split_queue_lock);
        count = page_count(head);
        mapcount = total_mapcount(head);
-       if (!mapcount && count == 1) {
+       if (!mapcount && page_ref_freeze(head, 1 + extra_pins)) {
                if (!list_empty(page_deferred_list(head))) {
                        pgdata->split_queue_len--;
                        list_del(page_deferred_list(head));
                }
-               spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
-               __split_huge_page(page, list);
+               if (mapping)
+                       __dec_zone_page_state(page, NR_SHMEM_THPS);
+               spin_unlock(&pgdata->split_queue_lock);
+               __split_huge_page(page, list, flags);
                ret = 0;
-       } else if (IS_ENABLED(CONFIG_DEBUG_VM) && mapcount) {
-               spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
-               pr_alert("total_mapcount: %u, page_count(): %u\n",
-                               mapcount, count);
-               if (PageTail(page))
-                       dump_page(head, NULL);
-               dump_page(page, "total_mapcount(head) > 0");
-               BUG();
        } else {
-               spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
+               if (IS_ENABLED(CONFIG_DEBUG_VM) && mapcount) {
+                       pr_alert("total_mapcount: %u, page_count(): %u\n",
+                                       mapcount, count);
+                       if (PageTail(page))
+                               dump_page(head, NULL);
+                       dump_page(page, "total_mapcount(head) > 0");
+                       BUG();
+               }
+               spin_unlock(&pgdata->split_queue_lock);
+fail:          if (mapping)
+                       spin_unlock(&mapping->tree_lock);
+               spin_unlock_irqrestore(&page_zone(head)->lru_lock, flags);
                unfreeze_page(head);
                ret = -EBUSY;
        }
 
 out_unlock:
-       anon_vma_unlock_write(anon_vma);
-       put_anon_vma(anon_vma);
+       if (anon_vma) {
+               anon_vma_unlock_write(anon_vma);
+               put_anon_vma(anon_vma);
+       }
+       if (mapping)
+               i_mmap_unlock_read(mapping);
 out:
        count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED);
        return ret;
@@ -3501,8 +3695,7 @@ static int split_huge_pages_set(void *data, u64 val)
                        if (zone != page_zone(page))
                                goto next;
 
-                       if (!PageHead(page) || !PageAnon(page) ||
-                                       PageHuge(page))
+                       if (!PageHead(page) || PageHuge(page) || !PageLRU(page))
                                goto next;
 
                        total++;