linux-kernel - [PATCH] highmem: Round down the address passed to kunmap_flush_on

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Message-Id: <20230126200727.1680362-1-willy@infradead.org>
Date:   Thu, 26 Jan 2023 20:07:27 +0000
From:   "Matthew Wilcox (Oracle)" <willy@...radead.org>
To:     Andrew Morton <akpm@...ux-foundation.org>,
        "Fabio M. De Francesco" <fmdefrancesco@...il.com>,
        Ira Weiny <ira.weiny@...el.com>, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org
Cc:     "Matthew Wilcox (Oracle)" <willy@...radead.org>,
        stable@...r.kernel.org
Subject: [PATCH] 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.

Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
Fixes: 298fa1ad5571 ("highmem: Provide generic variant of kmap_atomic*")
Cc: stable@...r.kernel.org
---
 include/linux/highmem-internal.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/linux/highmem-internal.h b/include/linux/highmem-internal.h
index 034b1106d022..e098f38422af 100644
--- a/include/linux/highmem-internal.h
+++ b/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))
-- 
2.35.1