netdev - [PATCH net-next -v5 3/4] mm: introduce __get_page() and __put

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Date:   Sat, 9 Oct 2021 17:37:23 +0800
From:   Yunsheng Lin <linyunsheng@...wei.com>
To:     <davem@...emloft.net>, <kuba@...nel.org>
CC:     <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linuxarm@...neuler.org>, <akpm@...ux-foundation.org>,
        <hawk@...nel.org>, <ilias.apalodimas@...aro.org>,
        <peterz@...radead.org>, <yuzhao@...gle.com>, <jhubbard@...dia.com>,
        <will@...nel.org>, <willy@...radead.org>, <jgg@...pe.ca>,
        <mcroce@...rosoft.com>, <willemb@...gle.com>,
        <cong.wang@...edance.com>, <pabeni@...hat.com>,
        <haokexin@...il.com>, <nogikh@...gle.com>, <elver@...gle.com>,
        <memxor@...il.com>, <vvs@...tuozzo.com>, <linux-mm@...ck.org>,
        <edumazet@...gle.com>, <alexander.duyck@...il.com>,
        <dsahern@...il.com>
Subject: [PATCH net-next -v5 3/4] mm: introduce __get_page() and __put_page()

Introduce __get_page() and __put_page() to operate on the
base page or head of a compound page for the cases when a
page is known to be a base page or head of a compound page.

Signed-off-by: Yunsheng Lin <linyunsheng@...wei.com>
---
 include/linux/mm.h | 21 ++++++++++++++-------
 mm/swap.c          |  6 +++---
 2 files changed, 17 insertions(+), 10 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 73a52aba448f..5683313c3e9d 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -902,7 +902,7 @@ static inline struct page *virt_to_head_page(const void *x)
 	return compound_head(page);
 }
 
-void __put_page(struct page *page);
+void __put_single_or_compound_page(struct page *page);
 
 void put_pages_list(struct list_head *pages);
 
@@ -1203,9 +1203,8 @@ static inline bool is_pci_p2pdma_page(const struct page *page)
 #define page_ref_zero_or_close_to_overflow(page) \
 	((unsigned int) page_ref_count(page) + 127u <= 127u)
 
-static inline void get_page(struct page *page)
+static inline void __get_page(struct page *page)
 {
-	page = compound_head(page);
 	/*
 	 * Getting a normal page or the head of a compound page
 	 * requires to already have an elevated page->_refcount.
@@ -1214,6 +1213,11 @@ static inline void get_page(struct page *page)
 	page_ref_inc(page);
 }
 
+static inline void get_page(struct page *page)
+{
+	__get_page(compound_head(page));
+}
+
 bool __must_check try_grab_page(struct page *page, unsigned int flags);
 struct page *try_grab_compound_head(struct page *page, int refs,
 				    unsigned int flags);
@@ -1228,10 +1232,8 @@ static inline __must_check bool try_get_page(struct page *page)
 	return true;
 }
 
-static inline void put_page(struct page *page)
+static inline void __put_page(struct page *page)
 {
-	page = compound_head(page);
-
 	/*
 	 * For devmap managed pages we need to catch refcount transition from
 	 * 2 to 1, when refcount reach one it means the page is free and we
@@ -1244,7 +1246,12 @@ static inline void put_page(struct page *page)
 	}
 
 	if (put_page_testzero(page))
-		__put_page(page);
+		__put_single_or_compound_page(page);
+}
+
+static inline void put_page(struct page *page)
+{
+	__put_page(compound_head(page));
 }
 
 /*
diff --git a/mm/swap.c b/mm/swap.c
index af3cad4e5378..565cbde1caea 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -111,7 +111,7 @@ static void __put_compound_page(struct page *page)
 	destroy_compound_page(page);
 }
 
-void __put_page(struct page *page)
+void __put_single_or_compound_page(struct page *page)
 {
 	if (is_zone_device_page(page)) {
 		put_dev_pagemap(page->pgmap);
@@ -128,7 +128,7 @@ void __put_page(struct page *page)
 	else
 		__put_single_page(page);
 }
-EXPORT_SYMBOL(__put_page);
+EXPORT_SYMBOL(__put_single_or_compound_page);
 
 /**
  * put_pages_list() - release a list of pages
@@ -1153,7 +1153,7 @@ void put_devmap_managed_page(struct page *page)
 	if (count == 1)
 		free_devmap_managed_page(page);
 	else if (!count)
-		__put_page(page);
+		__put_single_or_compound_page(page);
 }
 EXPORT_SYMBOL(put_devmap_managed_page);
 #endif
-- 
2.33.0