[MIPS] Fix buggy invocations of kmap_coherent()

kmap_coherent will only work correctly if the page it is called on is
not marked dirty.  If it's dirty the kernel address of the page should
be used instead of a temporary mapping.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 10 insertions, 5 deletions

diff --git a/arch/mips/mm/cache.c b/arch/mips/mm/cache.c
index 81f30ac2bff9..6a24651971df 100644
--- a/arch/mips/mm/cache.c
+++ b/arch/mips/mm/cache.c
@@ -92,12 +92,17 @@ EXPORT_SYMBOL(__flush_dcache_page);
 
 void __flush_anon_page(struct page *page, unsigned long vmaddr)
 {
-        if (pages_do_alias((unsigned long)page_address(page), vmaddr)) {
-                void *kaddr;
+        unsigned long addr = (unsigned long) page_address(page);
 
-                kaddr = kmap_coherent(page, vmaddr);
-                flush_data_cache_page((unsigned long)kaddr);
-                kunmap_coherent();
+        if (pages_do_alias(addr, vmaddr)) {
+                if (page_mapped(page) && !Page_dcache_dirty(page)) {
+                        void *kaddr;
+
+                        kaddr = kmap_coherent(page, vmaddr);
+                        flush_data_cache_page((unsigned long)kaddr);
+                        kunmap_coherent();
+                } else
+                        flush_data_cache_page(addr);
         }
 }