+ mm-highmem-align-down-to-page-the-address-for-kunmap_flush_on_unmap.patch added to mm-unstable branch

+ mm-highmem-align-down-to-page-the-address-for-kunmap_flush_on_unmap.patch added to mm-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm/highmem: align-down to page the address for kunmap_flush_on_unmap()
has been added to the -mm mm-unstable branch.  Its filename is
     mm-highmem-align-down-to-page-the-address-for-kunmap_flush_on_unmap.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-highmem-align-down-to-page-the-address-for-kunmap_flush_on_unmap.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days

------------------------------------------------------
From: "Fabio M. De Francesco" <fmdefrancesco@gmail.com>
Subject: mm/highmem: align-down to page the address for kunmap_flush_on_unmap()
Date: Thu, 26 Jan 2023 15:33:46 +0100

If ARCH_HAS_FLUSH_ON_KUNMAP is defined (PA-RISC case), __kunmap_local()
calls kunmap_flush_on_unmap().  The latter currently flushes the wrong
address (as confirmed by Matthew Wilcox and Helge Deller).  Al Viro
proposed to call kunmap_flush_on_unmap() on an aligned-down to page
address in order to fix this issue.  Consensus has been reached on this
solution.

Therefore, if ARCH_HAS_FLUSH_ON_KUNMAP is defined, call
kunmap_flush_on_unmap() on an aligned-down to page address computed with
the PTR_ALIGN_DOWN() macro.

Link: https://lkml.kernel.org/r/20230126143346.12086-1-fmdefrancesco@gmail.com
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Fixes: f3ba3c710ac5 ("mm/highmem: Provide kmap_local*")
Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Helge Deller <deller@gmx.de>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Bagas Sanjaya <bagasdotme@gmail.com>
Cc: David Sterba <dsterba@suse.com>
Cc: "Fabio M. De Francesco" <fmdefrancesco@gmail.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/linux/highmem-internal.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/include/linux/highmem-internal.h~mm-highmem-align-down-to-page-the-address-for-kunmap_flush_on_unmap
+++ a/include/linux/highmem-internal.h
@@ -200,7 +200,7 @@ static inline void *kmap_local_pfn(unsig
 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
 }
 
_

Patches currently in -mm which might be from fmdefrancesco@gmail.com are

mm-highmem-add-notes-about-conversions-from-kmap_atomic.patch
mm-highmem-add-notes-about-conversions-from-kmap_atomic-v3.patch
mm-highmem-align-down-to-page-the-address-for-kunmap_flush_on_unmap.patch