linux-kernel - [PATCH 4.4 09/99] MIPS: Handle highmem pages in __update

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Message-Id: <20160605213903.846777961@linuxfoundation.org>
Date:	Sun,  5 Jun 2016 14:40:42 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Paul Burton <paul.burton@...tec.com>,
	Lars Persson <lars.persson@...s.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jerome Marchand <jmarchan@...hat.com>,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	linux-mips@...ux-mips.org, Ralf Baechle <ralf@...ux-mips.org>
Subject: [PATCH 4.4 09/99] MIPS: Handle highmem pages in __update_cache

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Paul Burton <paul.burton@...tec.com>

commit f4281bba818105c7c91799abe40bc05c0dbdaa25 upstream.

The following patch will expose __update_cache to highmem pages. Handle
them by mapping them in for the duration of the cache maintenance, just
like in __flush_dcache_page. The code for that isn't shared because we
need the page address in __update_cache so sharing became messy. Given
that the entirity is an extra 5 lines, just duplicate it.

Signed-off-by: Paul Burton <paul.burton@...tec.com>
Cc: Lars Persson <lars.persson@...s.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Jerome Marchand <jmarchan@...hat.com>
Cc: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
Cc: linux-mips@...ux-mips.org
Cc: linux-kernel@...r.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/12721/
Signed-off-by: Ralf Baechle <ralf@...ux-mips.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/mips/mm/cache.c |   10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

--- a/arch/mips/mm/cache.c
+++ b/arch/mips/mm/cache.c
@@ -143,9 +143,17 @@ void __update_cache(struct vm_area_struc
 		return;
 	page = pfn_to_page(pfn);
 	if (page_mapping(page) && Page_dcache_dirty(page)) {
-		addr = (unsigned long) page_address(page);
+		if (PageHighMem(page))
+			addr = (unsigned long)kmap_atomic(page);
+		else
+			addr = (unsigned long)page_address(page);
+
 		if (exec || pages_do_alias(addr, address & PAGE_MASK))
 			flush_data_cache_page(addr);
+
+		if (PageHighMem(page))
+			__kunmap_atomic((void *)addr);
+
 		ClearPageDcacheDirty(page);
 	}
 }