thp: introduce khugepaged_prealloc_page and khugepaged_alloc_page

They are used to abstract the difference between NUMA enabled and NUMA
disabled to make the code more readable

Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 9c4390f..f0e9993 100644 (file)
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1827,28 +1827,34 @@ static void __collapse_huge_page_copy(pte_t *pte, struct page *page,
        }
 }
 
-static void collapse_huge_page(struct mm_struct *mm,
-                              unsigned long address,
-                              struct page **hpage,
-                              struct vm_area_struct *vma,
-                              int node)
+static void khugepaged_alloc_sleep(void)
 {
-       pgd_t *pgd;
-       pud_t *pud;
-       pmd_t *pmd, _pmd;
-       pte_t *pte;
-       pgtable_t pgtable;
-       struct page *new_page;
-       spinlock_t *ptl;
-       int isolated;
-       unsigned long hstart, hend;
+       wait_event_freezable_timeout(khugepaged_wait, false,
+                       msecs_to_jiffies(khugepaged_alloc_sleep_millisecs));
+}
 
-       VM_BUG_ON(address & ~HPAGE_PMD_MASK);
-#ifndef CONFIG_NUMA
-       up_read(&mm->mmap_sem);
-       VM_BUG_ON(!*hpage);
-       new_page = *hpage;
-#else
+#ifdef CONFIG_NUMA
+static bool khugepaged_prealloc_page(struct page **hpage, bool *wait)
+{
+       if (IS_ERR(*hpage)) {
+               if (!*wait)
+                       return false;
+
+               *wait = false;
+               khugepaged_alloc_sleep();
+       } else if (*hpage) {
+               put_page(*hpage);
+               *hpage = NULL;
+       }
+
+       return true;
+}
+
+static struct page
+*khugepaged_alloc_page(struct page **hpage, struct mm_struct *mm,
+                      struct vm_area_struct *vma, unsigned long address,
+                      int node)
+{
        VM_BUG_ON(*hpage);
        /*
         * Allocate the page while the vma is still valid and under
@@ -1860,7 +1866,7 @@ static void collapse_huge_page(struct mm_struct *mm,
         * mmap_sem in read mode is good idea also to allow greater
         * scalability.
         */
-       new_page = alloc_hugepage_vma(khugepaged_defrag(), vma, address,
+       *hpage  = alloc_hugepage_vma(khugepaged_defrag(), vma, address,
                                      node, __GFP_OTHER_NODE);
 
        /*
@@ -1868,15 +1874,81 @@ static void collapse_huge_page(struct mm_struct *mm,
         * preparation for taking it in write mode.
         */
        up_read(&mm->mmap_sem);
-       if (unlikely(!new_page)) {
+       if (unlikely(!*hpage)) {
                count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
                *hpage = ERR_PTR(-ENOMEM);
-               return;
+               return NULL;
        }
-       *hpage = new_page;
+
        count_vm_event(THP_COLLAPSE_ALLOC);
+       return *hpage;
+}
+#else
+static struct page *khugepaged_alloc_hugepage(bool *wait)
+{
+       struct page *hpage;
+
+       do {
+               hpage = alloc_hugepage(khugepaged_defrag());
+               if (!hpage) {
+                       count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
+                       if (!*wait)
+                               return NULL;
+
+                       *wait = false;
+                       khugepaged_alloc_sleep();
+               } else
+                       count_vm_event(THP_COLLAPSE_ALLOC);
+       } while (unlikely(!hpage) && likely(khugepaged_enabled()));
+
+       return hpage;
+}
+
+static bool khugepaged_prealloc_page(struct page **hpage, bool *wait)
+{
+       if (!*hpage)
+               *hpage = khugepaged_alloc_hugepage(wait);
+
+       if (unlikely(!*hpage))
+               return false;
+
+       return true;
+}
+
+static struct page
+*khugepaged_alloc_page(struct page **hpage, struct mm_struct *mm,
+                      struct vm_area_struct *vma, unsigned long address,
+                      int node)
+{
+       up_read(&mm->mmap_sem);
+       VM_BUG_ON(!*hpage);
+       return  *hpage;
+}
 #endif
 
+static void collapse_huge_page(struct mm_struct *mm,
+                                  unsigned long address,
+                                  struct page **hpage,
+                                  struct vm_area_struct *vma,
+                                  int node)
+{
+       pgd_t *pgd;
+       pud_t *pud;
+       pmd_t *pmd, _pmd;
+       pte_t *pte;
+       pgtable_t pgtable;
+       struct page *new_page;
+       spinlock_t *ptl;
+       int isolated;
+       unsigned long hstart, hend;
+
+       VM_BUG_ON(address & ~HPAGE_PMD_MASK);
+
+       /* release the mmap_sem read lock. */
+       new_page = khugepaged_alloc_page(hpage, mm, vma, address, node);
+       if (!new_page)
+               return;
+
        if (unlikely(mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL)))
                return;
 
@@ -2215,34 +2287,6 @@ static int khugepaged_wait_event(void)
                kthread_should_stop();
 }
 
-static void khugepaged_alloc_sleep(void)
-{
-       wait_event_freezable_timeout(khugepaged_wait, false,
-                       msecs_to_jiffies(khugepaged_alloc_sleep_millisecs));
-}
-
-#ifndef CONFIG_NUMA
-static struct page *khugepaged_alloc_hugepage(bool *wait)
-{
-       struct page *hpage;
-
-       do {
-               hpage = alloc_hugepage(khugepaged_defrag());
-               if (!hpage) {
-                       count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
-                       if (!*wait)
-                               return NULL;
-
-                       *wait = false;
-                       khugepaged_alloc_sleep();
-               } else
-                       count_vm_event(THP_COLLAPSE_ALLOC);
-       } while (unlikely(!hpage) && likely(khugepaged_enabled()));
-
-       return hpage;
-}
-#endif
-
 static void khugepaged_do_scan(void)
 {
        struct page *hpage = NULL;
@@ -2253,23 +2297,9 @@ static void khugepaged_do_scan(void)
        barrier(); /* write khugepaged_pages_to_scan to local stack */
 
        while (progress < pages) {
-#ifndef CONFIG_NUMA
-               if (!hpage)
-                       hpage = khugepaged_alloc_hugepage(&wait);
-
-               if (unlikely(!hpage))
+               if (!khugepaged_prealloc_page(&hpage, &wait))
                        break;
-#else
-               if (IS_ERR(hpage)) {
-                       if (!wait)
-                               break;
-                       wait = false;
-                       khugepaged_alloc_sleep();
-               } else if (hpage) {
-                       put_page(hpage);
-                       hpage = NULL;
-               }
-#endif
+
                cond_resched();
 
                if (unlikely(kthread_should_stop() || freezing(current)))