thp: compound_trans_order

Read compound_trans_order safe. Noop for CONFIG_TRANSPARENT_HUGEPAGE=n.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 26 insertions, 12 deletions

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 9c2695beab86..ce97a2bb0b19 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -450,6 +450,20 @@ static inline int compound_order(struct page *page)
         return (unsigned long)page[1].lru.prev;
 }
 
+static inline int compound_trans_order(struct page *page)
+{
+        int order;
+        unsigned long flags;
+
+        if (!PageHead(page))
+                return 0;
+
+        flags = compound_lock_irqsave(page);
+        order = compound_order(page);
+        compound_unlock_irqrestore(page, flags);
+        return order;
+}
+
 static inline void set_compound_order(struct page *page, unsigned long order)
 {
         page[1].lru.prev = (void *)order;
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index f4ea3410fb4d..741206ffdace 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1027,10 +1027,6 @@ mem_cgroup_get_reclaim_stat_from_page(struct page *page)
 {
         struct page_cgroup *pc;
         struct mem_cgroup_per_zone *mz;
-        int page_size = PAGE_SIZE;
-
-        if (PageTransHuge(page))
-                page_size <<= compound_order(page);
 
         if (mem_cgroup_disabled())
                 return NULL;
@@ -2286,8 +2282,10 @@ static int mem_cgroup_charge_common(struct page *page, struct mm_struct *mm,
         int ret;
         int page_size = PAGE_SIZE;
 
-        if (PageTransHuge(page))
+        if (PageTransHuge(page)) {
                 page_size <<= compound_order(page);
+                VM_BUG_ON(!PageTransHuge(page));
+        }
 
         pc = lookup_page_cgroup(page);
         /* can happen at boot */
@@ -2558,8 +2556,10 @@ __mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype)
         if (PageSwapCache(page))
                 return NULL;
 
-        if (PageTransHuge(page))
+        if (PageTransHuge(page)) {
                 page_size <<= compound_order(page);
+                VM_BUG_ON(!PageTransHuge(page));
+        }
 
         count = page_size >> PAGE_SHIFT;
         /*
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 1b43d0ffff65..548fbd70f026 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -203,7 +203,7 @@ static int kill_proc_ao(struct task_struct *t, unsigned long addr, int trapno,
 #ifdef __ARCH_SI_TRAPNO
         si.si_trapno = trapno;
 #endif
-        si.si_addr_lsb = compound_order(compound_head(page)) + PAGE_SHIFT;
+        si.si_addr_lsb = compound_trans_order(compound_head(page)) + PAGE_SHIFT;
         /*
          * Don't use force here, it's convenient if the signal
          * can be temporarily blocked.
@@ -930,7 +930,7 @@ static int hwpoison_user_mappings(struct page *p, unsigned long pfn,
 static void set_page_hwpoison_huge_page(struct page *hpage)
 {
         int i;
-        int nr_pages = 1 << compound_order(hpage);
+        int nr_pages = 1 << compound_trans_order(hpage);
         for (i = 0; i < nr_pages; i++)
                 SetPageHWPoison(hpage + i);
 }
@@ -938,7 +938,7 @@ static void set_page_hwpoison_huge_page(struct page *hpage)
 static void clear_page_hwpoison_huge_page(struct page *hpage)
 {
         int i;
-        int nr_pages = 1 << compound_order(hpage);
+        int nr_pages = 1 << compound_trans_order(hpage);
         for (i = 0; i < nr_pages; i++)
                 ClearPageHWPoison(hpage + i);
 }
@@ -968,7 +968,7 @@ int __memory_failure(unsigned long pfn, int trapno, int flags)
                 return 0;
         }
 
-        nr_pages = 1 << compound_order(hpage);
+        nr_pages = 1 << compound_trans_order(hpage);
         atomic_long_add(nr_pages, &mce_bad_pages);
 
         /*
@@ -1166,7 +1166,7 @@ int unpoison_memory(unsigned long pfn)
                 return 0;
         }
 
-        nr_pages = 1 << compound_order(page);
+        nr_pages = 1 << compound_trans_order(page);
 
         if (!get_page_unless_zero(page)) {
                 /*
@@ -1304,7 +1304,7 @@ static int soft_offline_huge_page(struct page *page, int flags)
         }
 done:
         if (!PageHWPoison(hpage))
-                atomic_long_add(1 << compound_order(hpage), &mce_bad_pages);
+                atomic_long_add(1 << compound_trans_order(hpage), &mce_bad_pages);
         set_page_hwpoison_huge_page(hpage);
         dequeue_hwpoisoned_huge_page(hpage);
         /* keep elevated page count for bad page */