linux-kernel - [PATCH 1/2] mm: call flush_dcache_page in memcpy_to_page and memzero

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Message-Id: <20210713055231.137602-2-hch@lst.de>
Date:   Tue, 13 Jul 2021 07:52:30 +0200
From:   Christoph Hellwig <hch@....de>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Ira Weiny <ira.weiny@...el.com>, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org
Subject: [PATCH 1/2] mm: call flush_dcache_page in memcpy_to_page and memzero_page

memcpy_to_page and memzero_page can write to arbitrary pages, which could
be in the page cache or in high memory, so  call flush_kernel_dcache_pages
to flush the dcache.

Fixes: bb90d4bc7b6a ("mm/highmem: Lift memcpy_[to|from]_page to core")
Fixes: 28961998f858 ("iov_iter: lift memzero_page() to highmem.h")
Signed-off-by: Christoph Hellwig <hch@....de>
---
 include/linux/highmem.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/linux/highmem.h b/include/linux/highmem.h
index 8c6e8e996c87..8e7e50a53a12 100644
--- a/include/linux/highmem.h
+++ b/include/linux/highmem.h
@@ -318,6 +318,7 @@ static inline void memcpy_to_page(struct page *page, size_t offset,
 
 	VM_BUG_ON(offset + len > PAGE_SIZE);
 	memcpy(to + offset, from, len);
+	flush_dcache_page(page);
 	kunmap_local(to);
 }
 
@@ -325,6 +326,7 @@ static inline void memzero_page(struct page *page, size_t offset, size_t len)
 {
 	char *addr = kmap_atomic(page);
 	memset(addr + offset, 0, len);
+	flush_dcache_page(page);
 	kunmap_atomic(addr);
 }
 
-- 
2.30.2