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From:   Oleksandr Natalenko <oleksandr@natalenko.name>
To:     linux-kernel@vger.kernel.org
Cc:     linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
        Vlastimil Babka <vbabka@suse.cz>,
        Matthew Wilcox <willy@infradead.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Miaohe Lin <linmiaohe@huawei.com>,
        Michal Hocko <mhocko@kernel.org>,
        Mel Gorman <mgorman@techsingularity.net>,
        Stephen Rothwell <sfr@canb.auug.org.au>
Subject: [RFC PATCH 0/1] mm: provide one common K(x) macro
Date:   Wed,  1 Sep 2021 11:21:48 +0200
Message-Id: <20210901092149.994791-1-oleksandr@natalenko.name>
MIME-Version: 1.0
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Precedence: bulk

Based on discussion with Miaohe Lin [1].

There are various places where the K(x) macro is defined, sometimes
under different names, sometimes it is just open-coded. In this RFC I
suggest providing a common K(x) definition that replaces existing ones.

For that, a new header, mm_tools.h, is created. I couldn't find a more
appropriate place for K(x). Probably, an existing header like mm_inline.h
would work as well. I tried placing this macro under mm.h, but then it
conflicts with uapi/linux/keyboard.h.

In case this approach is acceptable, replacing open-coded variants would
be done in a separate patch. For now, I'm using `git grep -nE
'<<\s?\(PAGE_SHIFT\s?\-\s?10\)'` to find such places.

Also note, here I do not touch files under arch/ like
arch/arc/include/asm/arcregs.h where PAGES_TO_KB() is defined, or
arch/powerpc/platforms/pseries/cmm.c with PAGES2KB() as well as
arch/s390/appldata/appldata_mem.c with P2K() as I'm not sure if it is
appropriate to include another header file there.

The patch is based on top of next-20210831 and is compile-tested using
allyesconfig.

Please let me know what you think.

Thanks.

[1] https://lore.kernel.org/linux-mm/9161665.bUqNH3lxUD@natalenko.name/

Oleksandr Natalenko (1):
  mm: provide one common K(x) macro

 drivers/base/node.c                 |  2 +-
 drivers/scsi/mpt3sas/mpt3sas_base.c |  5 ++---
 drivers/xen/xen-balloon.c           | 11 +++++------
 include/linux/mm_tools.h            |  9 +++++++++
 include/trace/events/writeback.h    | 19 +++++++++----------
 kernel/debug/kdb/kdb_main.c         |  2 +-
 mm/backing-dev.c                    |  3 +--
 mm/memcontrol.c                     |  2 +-
 mm/oom_kill.c                       |  3 +--
 mm/page_alloc.c                     |  3 +--
 10 files changed, 31 insertions(+), 28 deletions(-)
 create mode 100644 include/linux/mm_tools.h

-- 
2.33.0