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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Hou Tao <houtao1@huawei.com>,
        Jens Axboe <axboe@kernel.dk>
Subject: [PATCH 5.0 031/139] brd: re-enable __GFP_HIGHMEM in brd_insert_page()
Date:   Thu, 23 May 2019 21:05:19 +0200
Message-Id: <20190523181724.775119691@linuxfoundation.org>
In-Reply-To: <20190523181720.120897565@linuxfoundation.org>
References: <20190523181720.120897565@linuxfoundation.org>
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From: Hou Tao <houtao1@huawei.com>

commit f6b50160a06d4a0d6a3999ab0c5aec4f52dba248 upstream.

__GFP_HIGHMEM is disabled if dax is enabled on brd, however
dax support for brd has been removed since commit (7a862fbbdec6
"brd: remove dax support"), so restore __GFP_HIGHMEM in
brd_insert_page().

Also remove the no longer applicable comments about DAX and highmem.

Cc: stable@vger.kernel.org
Fixes: 7a862fbbdec6 ("brd: remove dax support")
Signed-off-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/block/brd.c |    7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

--- a/drivers/block/brd.c
+++ b/drivers/block/brd.c
@@ -96,13 +96,8 @@ static struct page *brd_insert_page(stru
 	/*
 	 * Must use NOIO because we don't want to recurse back into the
 	 * block or filesystem layers from page reclaim.
-	 *
-	 * Cannot support DAX and highmem, because our ->direct_access
-	 * routine for DAX must return memory that is always addressable.
-	 * If DAX was reworked to use pfns and kmap throughout, this
-	 * restriction might be able to be lifted.
 	 */
-	gfp_flags = GFP_NOIO | __GFP_ZERO;
+	gfp_flags = GFP_NOIO | __GFP_ZERO | __GFP_HIGHMEM;
 	page = alloc_page(gfp_flags);
 	if (!page)
 		return NULL;