highmem: round down the address passed to kunmap_flush_on_unmap()

We already round down the address in kunmap_local_indexed() which is the
other implementation of __kunmap_local().  The only implementation of
kunmap_flush_on_unmap() is PA-RISC which is expecting a page-aligned
address.  This may be causing PA-RISC to be flushing the wrong addresses
currently.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Matthew Wilcox (Oracle) <[email protected]>
Fixes: 298fa1a ("highmem: Provide generic variant of kmap_atomic*")
Reviewed-by: Ira Weiny <[email protected]>
Cc: "Fabio M. De Francesco" <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Helge Deller <[email protected]>
Cc: Alexander Potapenko <[email protected]>
Cc: Andrey Konovalov <[email protected]>
Cc: Bagas Sanjaya <[email protected]>
Cc: David Sterba <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Sebastian Andrzej Siewior <[email protected]>
Cc: Tony Luck <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: Matthew Wilcox (Oracle)

include/linux/highmem-internal.h

@@ -200,7 +200,7 @@ static inline void *kmap_local_pfn(unsigned long pfn)
 static inline void __kunmap_local(const void *addr)
 {
 #ifdef ARCH_HAS_FLUSH_ON_KUNMAP
-	kunmap_flush_on_unmap(addr);
+	kunmap_flush_on_unmap(PTR_ALIGN_DOWN(addr, PAGE_SIZE));
 #endif
 }
 
@@ -227,7 +227,7 @@ static inline void *kmap_atomic_pfn(unsigned long pfn)
 static inline void __kunmap_atomic(const void *addr)
 {
 #ifdef ARCH_HAS_FLUSH_ON_KUNMAP
-	kunmap_flush_on_unmap(addr);
+	kunmap_flush_on_unmap(PTR_ALIGN_DOWN(addr, PAGE_SIZE));
 #endif
 	pagefault_enable();
 	if (IS_ENABLED(CONFIG_PREEMPT_RT))