Re: [PATCH v20 04/20] mm/thp: use head for head page in lru_add_page_tail

[Alex Shi <alex.shi@linux.alibaba.com>]

在 2020/10/29 下午9:50, Johannes Weiner 写道:
> On Thu, Oct 29, 2020 at 06:44:49PM +0800, Alex Shi wrote:
>> Since the first parameter is only used by head page, it's better to make
>> it explicit.
>>
>> Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com>
>> Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
>> Acked-by: Hugh Dickins <hughd@google.com>
>> Cc: Andrew Morton <akpm@linux-foundation.org>
>> Cc: Johannes Weiner <hannes@cmpxchg.org>
>> Cc: Matthew Wilcox <willy@infradead.org>
>> Cc: Hugh Dickins <hughd@google.com>
>> Cc: linux-mm@kvack.org
>> Cc: linux-kernel@vger.kernel.org
>> ---
>>  mm/huge_memory.c | 12 ++++++------
>>  1 file changed, 6 insertions(+), 6 deletions(-)
>>
>> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
>> index 038db815ebba..93c0b73eb8c6 100644
>> --- a/mm/huge_memory.c
>> +++ b/mm/huge_memory.c
>> @@ -2346,19 +2346,19 @@ static void remap_page(struct page *page, unsigned int nr)
>>  	}
>>  }
>>  
>> -static void lru_add_page_tail(struct page *page, struct page *page_tail,
>> +static void lru_add_page_tail(struct page *head, struct page *page_tail,
> 
> It may be better to pick either
> 	head and tail

Hi Johannes,

Thanks for comments!

Right, Consider functions in this file are using head/tail more as parameters
I will change to use head/tail too. And then, the 04th, 05th, and 18th patch 
will be changed accordingly.

Thanks
Alex

> or
> 	page_head and page_tail
> 
> ?
> 

From a9ee63a213f40eb4d5a69b52fbb348ff9cd7cf6c Mon Sep 17 00:00:00 2001
From: Alex Shi <alex.shi@linux.alibaba.com>
Date: Tue, 26 May 2020 16:49:22 +0800
Subject: [PATCH v21 04/20] mm/thp: use head for head page in lru_add_page_tail

Since the first parameter is only used by head page, it's better to make
it explicit.

Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com>
Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
---
 mm/huge_memory.c | 23 +++++++++++------------
 1 file changed, 11 insertions(+), 12 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 038db815ebba..32a4bf5b80c8 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2346,33 +2346,32 @@ static void remap_page(struct page *page, unsigned int nr)
 	}
 }
 
-static void lru_add_page_tail(struct page *page, struct page *page_tail,
+static void lru_add_page_tail(struct page *head, struct page *tail,
 		struct lruvec *lruvec, struct list_head *list)
 {
-	VM_BUG_ON_PAGE(!PageHead(page), page);
-	VM_BUG_ON_PAGE(PageCompound(page_tail), page);
-	VM_BUG_ON_PAGE(PageLRU(page_tail), page);
+	VM_BUG_ON_PAGE(!PageHead(head), head);
+	VM_BUG_ON_PAGE(PageCompound(tail), head);
+	VM_BUG_ON_PAGE(PageLRU(tail), head);
 	lockdep_assert_held(&lruvec_pgdat(lruvec)->lru_lock);
 
 	if (!list)
-		SetPageLRU(page_tail);
+		SetPageLRU(tail);
 
-	if (likely(PageLRU(page)))
-		list_add_tail(&page_tail->lru, &page->lru);
+	if (likely(PageLRU(head)))
+		list_add_tail(&tail->lru, &head->lru);
 	else if (list) {
 		/* page reclaim is reclaiming a huge page */
-		get_page(page_tail);
-		list_add_tail(&page_tail->lru, list);
+		get_page(tail);
+		list_add_tail(&tail->lru, list);
 	} else {
 		/*
 		 * Head page has not yet been counted, as an hpage,
 		 * so we must account for each subpage individually.
 		 *
-		 * Put page_tail on the list at the correct position
+		 * Put tail on the list at the correct position
 		 * so they all end up in order.
 		 */
-		add_page_to_lru_list_tail(page_tail, lruvec,
-					  page_lru(page_tail));
+		add_page_to_lru_list_tail(tail, lruvec, page_lru(tail));
 	}
 }
 
-- 
1.8.3.1