Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
From:   Ankur Arora <ankur.a.arora@oracle.com>
To:     linux-kernel@vger.kernel.org, linux-mm@kvack.org
Cc:     kirill@shutemov.name, mhocko@kernel.org,
        boris.ostrovsky@oracle.com, konrad.wilk@oracle.com,
        Ankur Arora <ankur.a.arora@oracle.com>,
        Andrew Morton <akpm@linux-foundation.org>
Subject: [PATCH 6/8] mm, clear_huge_page: use clear_page_uncached() for gigantic pages
Date:   Wed, 14 Oct 2020 01:32:57 -0700
Message-Id: <20201014083300.19077-7-ankur.a.arora@oracle.com>
In-Reply-To: <20201014083300.19077-1-ankur.a.arora@oracle.com>
References: <20201014083300.19077-1-ankur.a.arora@oracle.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

Uncached writes are suitable for circumstances where the region written to
is not expected to be read again soon, or the region written to is large
enough that there's no expectation that we will find the writes in the
cache.

Accordingly switch to using clear_page_uncached() for gigantic pages.

Signed-off-by: Ankur Arora <ankur.a.arora@oracle.com>
---
 mm/memory.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/memory.c b/mm/memory.c
index eeae590e526a..4d2c58f83ab1 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -5092,7 +5092,7 @@ static void clear_gigantic_page(struct page *page,
 	for (i = 0; i < pages_per_huge_page;
 	     i++, p = mem_map_next(p, page, i)) {
 		cond_resched();
-		clear_user_highpage(p, addr + i * PAGE_SIZE);
+		clear_user_highpage_uncached(p, addr + i * PAGE_SIZE);
 	}
 }
 
@@ -5111,6 +5111,7 @@ void clear_huge_page(struct page *page,
 
 	if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
 		clear_gigantic_page(page, addr, pages_per_huge_page);
+		clear_page_uncached_flush();
 		return;
 	}
 
-- 
2.9.3