mm: thp: fix DEBUG_PAGEALLOC oops in copy_page_rep()

[uclinux-h8/linux.git] / mm / huge_memory.c

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index d199d2d..bade35e 100644 (file)
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -5,6 +5,8 @@
  *  the COPYING file in the top-level directory.
  */
 
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
 #include <linux/mm.h>
 #include <linux/sched.h>
 #include <linux/highmem.h>
@@ -151,8 +153,7 @@ static int start_khugepaged(void)
                        khugepaged_thread = kthread_run(khugepaged, NULL,
                                                        "khugepaged");
                if (unlikely(IS_ERR(khugepaged_thread))) {
-                       printk(KERN_ERR
-                              "khugepaged: kthread_run(khugepaged) failed\n");
+                       pr_err("khugepaged: kthread_run(khugepaged) failed\n");
                        err = PTR_ERR(khugepaged_thread);
                        khugepaged_thread = NULL;
                }
@@ -584,19 +585,19 @@ static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj)
 
        *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj);
        if (unlikely(!*hugepage_kobj)) {
-               printk(KERN_ERR "hugepage: failed to create transparent hugepage kobject\n");
+               pr_err("failed to create transparent hugepage kobject\n");
                return -ENOMEM;
        }
 
        err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group);
        if (err) {
-               printk(KERN_ERR "hugepage: failed to register transparent hugepage group\n");
+               pr_err("failed to register transparent hugepage group\n");
                goto delete_obj;
        }
 
        err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group);
        if (err) {
-               printk(KERN_ERR "hugepage: failed to register transparent hugepage group\n");
+               pr_err("failed to register transparent hugepage group\n");
                goto remove_hp_group;
        }
 
@@ -689,8 +690,7 @@ static int __init setup_transparent_hugepage(char *str)
        }
 out:
        if (!ret)
-               printk(KERN_WARNING
-                      "transparent_hugepage= cannot parse, ignored\n");
+               pr_warn("transparent_hugepage= cannot parse, ignored\n");
        return ret;
 }
 __setup("transparent_hugepage=", setup_transparent_hugepage);
@@ -941,6 +941,37 @@ unlock:
        spin_unlock(ptl);
 }
 
+/*
+ * Save CONFIG_DEBUG_PAGEALLOC from faulting falsely on tail pages
+ * during copy_user_huge_page()'s copy_page_rep(): in the case when
+ * the source page gets split and a tail freed before copy completes.
+ * Called under pmd_lock of checked pmd, so safe from splitting itself.
+ */
+static void get_user_huge_page(struct page *page)
+{
+       if (IS_ENABLED(CONFIG_DEBUG_PAGEALLOC)) {
+               struct page *endpage = page + HPAGE_PMD_NR;
+
+               atomic_add(HPAGE_PMD_NR, &page->_count);
+               while (++page < endpage)
+                       get_huge_page_tail(page);
+       } else {
+               get_page(page);
+       }
+}
+
+static void put_user_huge_page(struct page *page)
+{
+       if (IS_ENABLED(CONFIG_DEBUG_PAGEALLOC)) {
+               struct page *endpage = page + HPAGE_PMD_NR;
+
+               while (page < endpage)
+                       put_page(page++);
+       } else {
+               put_page(page);
+       }
+}
+
 static int do_huge_pmd_wp_page_fallback(struct mm_struct *mm,
                                        struct vm_area_struct *vma,
                                        unsigned long address,
@@ -1074,7 +1105,7 @@ int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
                ret |= VM_FAULT_WRITE;
                goto out_unlock;
        }
-       get_page(page);
+       get_user_huge_page(page);
        spin_unlock(ptl);
 alloc:
        if (transparent_hugepage_enabled(vma) &&
@@ -1095,7 +1126,7 @@ alloc:
                                split_huge_page(page);
                                ret |= VM_FAULT_FALLBACK;
                        }
-                       put_page(page);
+                       put_user_huge_page(page);
                }
                count_vm_event(THP_FAULT_FALLBACK);
                goto out;
@@ -1105,7 +1136,7 @@ alloc:
                put_page(new_page);
                if (page) {
                        split_huge_page(page);
-                       put_page(page);
+                       put_user_huge_page(page);
                } else
                        split_huge_page_pmd(vma, address, pmd);
                ret |= VM_FAULT_FALLBACK;
@@ -1127,7 +1158,7 @@ alloc:
 
        spin_lock(ptl);
        if (page)
-               put_page(page);
+               put_user_huge_page(page);
        if (unlikely(!pmd_same(*pmd, orig_pmd))) {
                spin_unlock(ptl);
                mem_cgroup_uncharge_page(new_page);
@@ -1830,10 +1861,11 @@ static void __split_huge_page(struct page *page,
         * the newly established pmd of the child later during the
         * walk, to be able to set it as pmd_trans_splitting too.
         */
-       if (mapcount != page_mapcount(page))
-               printk(KERN_ERR "mapcount %d page_mapcount %d\n",
-                      mapcount, page_mapcount(page));
-       BUG_ON(mapcount != page_mapcount(page));
+       if (mapcount != page_mapcount(page)) {
+               pr_err("mapcount %d page_mapcount %d\n",
+                       mapcount, page_mapcount(page));
+               BUG();
+       }
 
        __split_huge_page_refcount(page, list);
 
@@ -1844,10 +1876,11 @@ static void __split_huge_page(struct page *page,
                BUG_ON(is_vma_temporary_stack(vma));
                mapcount2 += __split_huge_page_map(page, vma, addr);
        }
-       if (mapcount != mapcount2)
-               printk(KERN_ERR "mapcount %d mapcount2 %d page_mapcount %d\n",
-                      mapcount, mapcount2, page_mapcount(page));
-       BUG_ON(mapcount != mapcount2);
+       if (mapcount != mapcount2) {
+               pr_err("mapcount %d mapcount2 %d page_mapcount %d\n",
+                       mapcount, mapcount2, page_mapcount(page));
+               BUG();
+       }
 }
 
 /*