mm/hwpoison: don't need to hold compound lock for hugetlbfs page

compound lock is introduced by commit e9da73d("thp: compound_lock."), it
is used to serialize put_page against __split_huge_page_refcount().  In
addition, transparent hugepages will be splitted in hwpoison handler and
just one subpage will be poisoned.  There is unnecessary to hold compound
lock for hugetlbfs page.  This patch replace compound_trans_order by
compond_order in the place where the page is hugetlbfs page.

Signed-off-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Tony Luck <tony.luck@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/mm.h

@@ -495,20 +495,6 @@ 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;

mm/memory-failure.c

@@ -206,7 +206,7 @@ static int kill_proc(struct task_struct *t, unsigned long addr, int trapno,
 #ifdef __ARCH_SI_TRAPNO
 	si.si_trapno = trapno;
 #endif
-	si.si_addr_lsb = compound_trans_order(compound_head(page)) + PAGE_SHIFT;
+	si.si_addr_lsb = compound_order(compound_head(page)) + PAGE_SHIFT;
 
 	if ((flags & MF_ACTION_REQUIRED) && t == current) {
 		si.si_code = BUS_MCEERR_AR;
@@ -983,15 +983,15 @@ 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_trans_order(hpage);
+	int nr_pages = 1 << compound_order(hpage);
 	for (i = 0; i < nr_pages; i++)
 		SetPageHWPoison(hpage + i);
 }
 
 static void clear_page_hwpoison_huge_page(struct page *hpage)
 {
 	int i;
-	int nr_pages = 1 << compound_trans_order(hpage);
+	int nr_pages = 1 << compound_order(hpage);
 	for (i = 0; i < nr_pages; i++)
 		ClearPageHWPoison(hpage + i);
 }
@@ -1342,7 +1342,7 @@ int unpoison_memory(unsigned long pfn)
 		return 0;
 	}
 
-	nr_pages = 1 << compound_trans_order(page);
+	nr_pages = 1 << compound_order(page);
 
 	if (!get_page_unless_zero(page)) {
 		/*
@@ -1506,7 +1506,7 @@ static int soft_offline_huge_page(struct page *page, int flags)
 	} else {
 		set_page_hwpoison_huge_page(hpage);
 		dequeue_hwpoisoned_huge_page(hpage);
-		atomic_long_add(1 << compound_trans_order(hpage),
+		atomic_long_add(1 << compound_order(hpage),
 				&num_poisoned_pages);
 	}
 	return ret;
@@ -1566,7 +1566,7 @@ int soft_offline_page(struct page *page, int flags)
 		if (PageHuge(page)) {
 			set_page_hwpoison_huge_page(hpage);
 			dequeue_hwpoisoned_huge_page(hpage);
-			atomic_long_add(1 << compound_trans_order(hpage),
+			atomic_long_add(1 << compound_order(hpage),
 					&num_poisoned_pages);
 		} else {
 			SetPageHWPoison(page);