From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1753002AbdDKDI1 (ORCPT <rfc822;w@1wt.eu>);
        Mon, 10 Apr 2017 23:08:27 -0400
Received: from LGEAMRELO11.lge.com ([156.147.23.51]:38601 "EHLO
        lgeamrelo11.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1751754AbdDKDIZ (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Mon, 10 Apr 2017 23:08:25 -0400
X-Original-SENDERIP: 156.147.1.126
X-Original-MAILFROM: minchan@kernel.org
X-Original-SENDERIP: 10.177.223.161
X-Original-MAILFROM: minchan@kernel.org
Date: Tue, 11 Apr 2017 12:08:23 +0900
From: Minchan Kim <minchan@kernel.org>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>,
        Michael Ellerman <mpe@ellerman.id.au>, linuxppc-dev@lists.ozlabs.org,
        linux-kernel@vger.kernel.org
Subject: clear_page, copy_page address align question?
Message-ID: <20170411030823.GB6545@bbox>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
User-Agent: Mutt/1.5.24 (2015-08-30)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

Hello,

When I tested zram in ppc64, I got random corruption.
With investigation, it seems clear_page corrupted the memory.
I passed 64K kmalloced(kmalloc(PAGE_SIZE)) address to clear_page
and turned on slub debug so address is not aligned with PAGE_SIZE.
Is it a valid usecase that non-PAGE_SIZE aligned address is
used for clear_page in ppc64?

As well, copy_page have same rule, too?

Anyway, when I changed clear_page to memset, it seems the problem
is gone.

Thanks.