linux-kernel - [PATCH v2 2/7] mm/hwpoison: don't need to hold compound lock for hugetlbfs page

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Message-Id: <1377253841-17620-2-git-send-email-liwanp@linux.vnet.ibm.com>
Date:	Fri, 23 Aug 2013 18:30:36 +0800
From:	Wanpeng Li <liwanp@...ux.vnet.ibm.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Andi Kleen <andi@...stfloor.org>,
	Fengguang Wu <fengguang.wu@...el.com>,
	Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
	Tony Luck <tony.luck@...el.com>, gong.chen@...ux.intel.com,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	Wanpeng Li <liwanp@...ux.vnet.ibm.com>
Subject: [PATCH v2 2/7] mm/hwpoison: don't need to hold compound lock for hugetlbfs page

v1 -> v2:
	* drop compound_trans_order completely

compound lock is introduced by commit e9da73d67("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.

Reviewed-by: Naoya Horiguchi <n-horiguchi@...jp.nec.com>
Signed-off-by: Wanpeng Li <liwanp@...ux.vnet.ibm.com>
---
 include/linux/mm.h  |   14 --------------
 mm/memory-failure.c |   12 ++++++------
 2 files changed, 6 insertions(+), 20 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index f022460..1745a2a 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -489,20 +489,6 @@ 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;
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 2c13aa7..efa6bd7 100644
--- a/mm/memory-failure.c
+++ b/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;
@@ -983,7 +983,7 @@ 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_trans_order(hpage);
+	int nr_pages = 1 << compound_order(hpage);
 	for (i = 0; i < nr_pages; i++)
 		SetPageHWPoison(hpage + i);
 }
@@ -991,7 +991,7 @@ 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_trans_order(hpage);
+	int nr_pages = 1 << compound_order(hpage);
 	for (i = 0; i < nr_pages; i++)
 		ClearPageHWPoison(hpage + i);
 }
@@ -1336,7 +1336,7 @@ 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)) {
 		/*
@@ -1491,7 +1491,7 @@ 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;
@@ -1551,7 +1551,7 @@ 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);
-- 
1.7.5.4

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