From: "Huang, Ying" <ying.huang@intel.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: tim.c.chen@intel.com, dave.hansen@intel.com,
andi.kleen@intel.com, aaron.lu@intel.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, Huang Ying <ying.huang@intel.com>,
Andrea Arcangeli <aarcange@redhat.com>,
"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
Ebru Akagunduz <ebru.akagunduz@gmail.com>
Subject: [PATCH -v5 7/9] mm, THP: Add can_split_huge_page()
Date: Wed, 16 Nov 2016 11:10:55 +0800 [thread overview]
Message-ID: <20161116031057.12977-8-ying.huang@intel.com> (raw)
In-Reply-To: <20161116031057.12977-1-ying.huang@intel.com>
From: Huang Ying <ying.huang@intel.com>
Separates checking whether we can split the huge page from
split_huge_page_to_list() into a function. This will help to check that
before splitting the THP (Transparent Huge Page) really.
This will be used for delaying splitting THP during swapping out. Where
for a THP, we will allocate a swap cluster, add the THP into the swap
cache, then split the THP. To avoid the unnecessary operations for the
un-splittable THP, we will check that firstly.
There is no functionality change in this patch.
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Ebru Akagunduz <ebru.akagunduz@gmail.com>
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
---
include/linux/huge_mm.h | 7 +++++++
mm/huge_memory.c | 17 ++++++++++++++---
2 files changed, 21 insertions(+), 3 deletions(-)
diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index 31f2c32..1ccb49d 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -94,6 +94,7 @@ extern unsigned long thp_get_unmapped_area(struct file *filp,
extern void prep_transhuge_page(struct page *page);
extern void free_transhuge_page(struct page *page);
+bool can_split_huge_page(struct page *page, int *pextra_pins);
int split_huge_page_to_list(struct page *page, struct list_head *list);
static inline int split_huge_page(struct page *page)
{
@@ -176,6 +177,12 @@ static inline void prep_transhuge_page(struct page *page) {}
#define thp_get_unmapped_area NULL
+static inline bool
+can_split_huge_page(struct page *page, int *pextra_pins)
+{
+ BUILD_BUG();
+ return false;
+}
static inline int
split_huge_page_to_list(struct page *page, struct list_head *list)
{
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 2d1d6bb..e894154 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2017,6 +2017,19 @@ int page_trans_huge_mapcount(struct page *page, int *total_mapcount)
return ret;
}
+/* Racy check whether the huge page can be split */
+bool can_split_huge_page(struct page *page, int *pextra_pins)
+{
+ int extra_pins = 0;
+
+ /* Additional pins from radix tree */
+ if (!PageAnon(page))
+ extra_pins = HPAGE_PMD_NR;
+ if (pextra_pins)
+ *pextra_pins = extra_pins;
+ return total_mapcount(page) == page_count(page) - extra_pins - 1;
+}
+
/*
* This function splits huge page into normal pages. @page can point to any
* subpage of huge page to split. Split doesn't change the position of @page.
@@ -2077,8 +2090,6 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
goto out;
}
- /* Addidional pins from radix tree */
- extra_pins = HPAGE_PMD_NR;
anon_vma = NULL;
i_mmap_lock_read(mapping);
}
@@ -2087,7 +2098,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
* Racy check if we can split the page, before freeze_page() will
* split PMDs
*/
- if (total_mapcount(head) != page_count(head) - extra_pins - 1) {
+ if (!can_split_huge_page(head, &extra_pins)) {
ret = -EBUSY;
goto out_unlock;
}
--
2.10.2
next prev parent reply other threads:[~2016-11-16 3:13 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-16 3:10 [PATCH -v5 0/9] THP swap: Delay splitting THP during swapping out Huang, Ying
2016-11-16 3:10 ` [PATCH -v5 1/9] mm, swap: Make swap cluster size same of THP size on x86_64 Huang, Ying
2016-11-16 3:10 ` [PATCH -v5 2/9] mm, memcg: Support to charge/uncharge multiple swap entries Huang, Ying
2016-11-16 3:10 ` [PATCH -v5 3/9] mm, THP, swap: Add swap cluster allocate/free functions Huang, Ying
2016-11-16 3:10 ` [PATCH -v5 4/9] mm, THP, swap: Add get_huge_swap_page() Huang, Ying
2016-11-16 3:10 ` [PATCH -v5 5/9] mm, THP, swap: Support to clear SWAP_HAS_CACHE for huge page Huang, Ying
2016-11-16 3:10 ` [PATCH -v5 6/9] mm, THP, swap: Support to add/delete THP to/from swap cache Huang, Ying
2016-11-16 3:10 ` Huang, Ying [this message]
2016-11-16 3:10 ` [PATCH -v5 8/9] mm, THP, swap: Support to split THP in " Huang, Ying
2016-11-16 3:10 ` [PATCH -v5 9/9] mm, THP, swap: Delay splitting THP during swap out Huang, Ying
2016-11-21 12:14 ` [PATCH -v5 0/9] THP swap: Delay splitting THP during swapping out Kirill A. Shutemov
2016-11-22 0:46 ` Huang, Ying
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