1 files changed, 41 insertions, 44 deletions

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 55478ab3c83b..f2d19e4fe854 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -632,37 +632,27 @@ release:
 static inline gfp_t alloc_hugepage_direct_gfpmask(struct vm_area_struct *vma, unsigned long addr)
 {
         const bool vma_madvised = !!(vma->vm_flags & VM_HUGEPAGE);
-        gfp_t this_node = 0;
-
-#ifdef CONFIG_NUMA
-        struct mempolicy *pol;
-        /*
-         * __GFP_THISNODE is used only when __GFP_DIRECT_RECLAIM is not
-         * specified, to express a general desire to stay on the current
-         * node for optimistic allocation attempts. If the defrag mode
-         * and/or madvise hint requires the direct reclaim then we prefer
-         * to fallback to other node rather than node reclaim because that
-         * can lead to excessive reclaim even though there is free memory
-         * on other nodes. We expect that NUMA preferences are specified
-         * by memory policies.
-         */
-        pol = get_vma_policy(vma, addr);
-        if (pol->mode != MPOL_BIND)
-                this_node = __GFP_THISNODE;
-        mpol_cond_put(pol);
-#endif
+        const gfp_t gfp_mask = GFP_TRANSHUGE_LIGHT | __GFP_THISNODE;
 
+        /* Always do synchronous compaction */
         if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags))
-                return GFP_TRANSHUGE | (vma_madvised ? 0 : __GFP_NORETRY);
+                return GFP_TRANSHUGE | __GFP_THISNODE |
+                       (vma_madvised ? 0 : __GFP_NORETRY);
+
+        /* Kick kcompactd and fail quickly */
         if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags))
-                return GFP_TRANSHUGE_LIGHT | __GFP_KSWAPD_RECLAIM | this_node;
+                return gfp_mask | __GFP_KSWAPD_RECLAIM;
+
+        /* Synchronous compaction if madvised, otherwise kick kcompactd */
         if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags))
-                return GFP_TRANSHUGE_LIGHT | (vma_madvised ? __GFP_DIRECT_RECLAIM :
-                                                             __GFP_KSWAPD_RECLAIM | this_node);
+                return gfp_mask | (vma_madvised ? __GFP_DIRECT_RECLAIM :
+                                                  __GFP_KSWAPD_RECLAIM);
+
+        /* Only do synchronous compaction if madvised */
         if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags))
-                return GFP_TRANSHUGE_LIGHT | (vma_madvised ? __GFP_DIRECT_RECLAIM :
-                                                             this_node);
-        return GFP_TRANSHUGE_LIGHT | this_node;
+                return gfp_mask | (vma_madvised ? __GFP_DIRECT_RECLAIM : 0);
+
+        return gfp_mask;
 }
 
 /* Caller must hold page table lock. */
@@ -2350,7 +2340,7 @@ void vma_adjust_trans_huge(struct vm_area_struct *vma,
         }
 }
 
-static void freeze_page(struct page *page)
+static void unmap_page(struct page *page)
 {
         enum ttu_flags ttu_flags = TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS |
                 TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD;
@@ -2365,7 +2355,7 @@ static void freeze_page(struct page *page)
         VM_BUG_ON_PAGE(!unmap_success, page);
 }
 
-static void unfreeze_page(struct page *page)
+static void remap_page(struct page *page)
 {
         int i;
         if (PageTransHuge(page)) {
@@ -2402,6 +2392,12 @@ static void __split_huge_page_tail(struct page *head, int tail,
                          (1L << PG_unevictable) |
                          (1L << PG_dirty)));
 
+        /* ->mapping in first tail page is compound_mapcount */
+        VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING,
+                        page_tail);
+        page_tail->mapping = head->mapping;
+        page_tail->index = head->index + tail;
+
         /* Page flags must be visible before we make the page non-compound. */
         smp_wmb();
 
@@ -2422,12 +2418,6 @@ static void __split_huge_page_tail(struct page *head, int tail,
         if (page_is_idle(head))
                 set_page_idle(page_tail);
 
-        /* ->mapping in first tail page is compound_mapcount */
-        VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING,
-                        page_tail);
-        page_tail->mapping = head->mapping;
-
-        page_tail->index = head->index + tail;
         page_cpupid_xchg_last(page_tail, page_cpupid_last(head));
 
         /*
@@ -2439,12 +2429,11 @@ static void __split_huge_page_tail(struct page *head, int tail,
 }
 
 static void __split_huge_page(struct page *page, struct list_head *list,
-                unsigned long flags)
+                pgoff_t end, unsigned long flags)
 {
         struct page *head = compound_head(page);
         struct zone *zone = page_zone(head);
         struct lruvec *lruvec;
-        pgoff_t end = -1;
         int i;
 
         lruvec = mem_cgroup_page_lruvec(head, zone->zone_pgdat);
@@ -2452,9 +2441,6 @@ static void __split_huge_page(struct page *page, struct list_head *list,
         /* complete memcg works before add pages to LRU */
         mem_cgroup_split_huge_fixup(head);
 
-        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 */
@@ -2483,7 +2469,7 @@ static void __split_huge_page(struct page *page, struct list_head *list,
 
         spin_unlock_irqrestore(zone_lru_lock(page_zone(head)), flags);
 
-        unfreeze_page(head);
+        remap_page(head);
 
         for (i = 0; i < HPAGE_PMD_NR; i++) {
                 struct page *subpage = head + i;
@@ -2626,6 +2612,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
         int count, mapcount, extra_pins, ret;
         bool mlocked;
         unsigned long flags;
+        pgoff_t end;
 
         VM_BUG_ON_PAGE(is_huge_zero_page(page), page);
         VM_BUG_ON_PAGE(!PageLocked(page), page);
@@ -2648,6 +2635,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
                         ret = -EBUSY;
                         goto out;
                 }
+                end = -1;
                 mapping = NULL;
                 anon_vma_lock_write(anon_vma);
         } else {
@@ -2661,10 +2649,19 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
 
                 anon_vma = NULL;
                 i_mmap_lock_read(mapping);
+
+                /*
+                 *__split_huge_page() may need to trim off pages beyond EOF:
+                 * but on 32-bit, i_size_read() takes an irq-unsafe seqlock,
+                 * which cannot be nested inside the page tree lock. So note
+                 * end now: i_size itself may be changed at any moment, but
+                 * head page lock is good enough to serialize the trimming.
+                 */
+                end = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE);
         }
 
         /*
-         * Racy check if we can split the page, before freeze_page() will
+         * Racy check if we can split the page, before unmap_page() will
          * split PMDs
          */
         if (!can_split_huge_page(head, &extra_pins)) {
@@ -2673,7 +2670,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
         }
 
         mlocked = PageMlocked(page);
-        freeze_page(head);
+        unmap_page(head);
         VM_BUG_ON_PAGE(compound_mapcount(head), head);
 
         /* Make sure the page is not on per-CPU pagevec as it takes pin */
@@ -2707,7 +2704,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
                 if (mapping)
                         __dec_node_page_state(page, NR_SHMEM_THPS);
                 spin_unlock(&pgdata->split_queue_lock);
-                __split_huge_page(page, list, flags);
+                __split_huge_page(page, list, end, flags);
                 if (PageSwapCache(head)) {
                         swp_entry_t entry = { .val = page_private(head) };
 
@@ -2727,7 +2724,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
 fail:           if (mapping)
                         xa_unlock(&mapping->i_pages);
                 spin_unlock_irqrestore(zone_lru_lock(page_zone(head)), flags);
-                unfreeze_page(head);
+                remap_page(head);
                 ret = -EBUSY;
         }