linux-kernel - [PATCH 6/6] mm/page_alloc.c: avoid allocating highmem pages via alloc_pages_exact

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Message-ID: <20210830141051.64090-7-linmiaohe@huawei.com>
Date:   Mon, 30 Aug 2021 22:10:51 +0800
From:   Miaohe Lin <linmiaohe@...wei.com>
To:     <akpm@...ux-foundation.org>
CC:     <vbabka@...e.cz>, <sfr@...b.auug.org.au>, <peterz@...radead.org>,
        <mgorman@...hsingularity.net>, <linux-mm@...ck.org>,
        <linux-kernel@...r.kernel.org>, <linmiaohe@...wei.com>
Subject: [PATCH 6/6] mm/page_alloc.c: avoid allocating highmem pages via alloc_pages_exact_nid()

Don't use with __GFP_HIGHMEM because page_address() cannot represent
highmem pages without kmap(). Newly allocated pages would leak as
page_address() will return NULL for highmem pages here. But It works
now because the only caller does not specify __GFP_HIGHMEM now.

Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
---
 mm/page_alloc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index d87b7e6e9e6b..858fd45ecaea 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5639,7 +5639,7 @@ void * __meminit alloc_pages_exact_nid(int nid, size_t size, gfp_t gfp_mask)
 	if (WARN_ON_ONCE(gfp_mask & __GFP_COMP))
 		gfp_mask &= ~__GFP_COMP;
 
-	p = alloc_pages_node(nid, gfp_mask, order);
+	p = alloc_pages_node(nid, gfp_mask & ~__GFP_HIGHMEM, order);
 	if (!p)
 		return NULL;
 	return make_alloc_exact((unsigned long)page_address(p), order, size);
-- 
2.23.0