From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751926AbbJLJ2U (ORCPT ); Mon, 12 Oct 2015 05:28:20 -0400 Received: from mout.kundenserver.de ([212.227.126.130]:55742 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751310AbbJLJ2T (ORCPT ); Mon, 12 Oct 2015 05:28:19 -0400 From: Arnd Bergmann To: linux-arm-kernel@lists.infradead.org Cc: Jongsung Kim , Russell King - ARM Linux , Nicolas Pitre , Gunho Lee , Chanho Min , linux-kernel@vger.kernel.org Subject: Re: [PATCH] ARM:mm: fix kmap_atomic_to_page Date: Mon, 12 Oct 2015 11:27:42 +0200 Message-ID: <5778996.I0Vmityi0g@wuerfel> User-Agent: KMail/4.11.5 (Linux/3.16.0-10-generic; KDE/4.11.5; x86_64; ; ) In-Reply-To: <561B457F.5090104@lge.com> References: <1444129773-12632-1-git-send-email-chanho.min@lge.com> <20151007090121.GC21513@n2100.arm.linux.org.uk> <561B457F.5090104@lge.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" X-Provags-ID: V03:K0:uq4WIOXdgEHbBbp5VqUe16CYtM631xqjvOyi3t2Q37w63QIOB4I gC9s9fXpkuGMPjSzau8wHFMEFWDUjgIdWBiVb5GybTUA+1pglxn7B7F5QZJj5fEH7NEn2fp 0E8yCf+lunehnVPY/un/56RaK5pyRAybD0yXMZsX0Iscq12tzjeMImwgrQ0bzo8z5qi4Awf dhcAlfmL7pHb5lU5WfTRA== X-UI-Out-Filterresults: notjunk:1;V01:K0:vLlGthmP0HE=:073kz5o0+M8uXsvOcIepGg rY9f1Y4jDEAWfiPaXC5a3tIOwt/bagwxOYtmu6FODNB5G0vq39ViUuZvuTYfVXuSBR9fpxpbV LdwdhBndGBZgdRHEgaplhDuzm49N9bk6OvPSd81FIzfT4F9YGGBfpNMxxMYaldmSjyflN2bK5 EoI8s21KCV0DwlyVXrdcQSVrkOKVk//zxN5Y7492veV0zqx0E9XWWsQhIB9HcB27/18abl8+s Yfh4vcYKlGguZypGKzzg66RUIAIcIqVYzfnOC+VeY5wHHliV7WzJNu3wKWALYoggM84hlmeLC hFhNMBrkhnzmW8b/AsG9U0BadEGCbbpxIQ4kGIdmNcxeszH4pJMagdZPfeOQSj+opKlPLl995 Ib/n9/QmzQzzUZ8kgpYsE6MmUTxxQTbwBjCqkMJ9PcEjpAxU3EaQYhSOf0zLYv+KCqfwScUE2 TGiXS2cDPXj417KkxaJ48q7lzkLWqCKCViEgIxhJpDPbRJHk39qSH/1G1KmFFTjvAb7NfGkPU Sr3QC512vN0HAm0I/uNAesxhGMCiGGwKKpi0cR9WmYAbl/tkDQGCOAYEr70KDC71ryVnO4Yhf aVecZT4CTYjuTnInZ88lkBreEaY7VrJy6iJdFIBVCu0cABtdphjpUx77bEBm15bGMLosbvzy+ QWp8yJdvAWNoKJVNBFr7JWVOVulzxF85cQpHT64PPuwoeYem1kvMKF/hHzEn9HnMCVtM8CnPR rln3VGExUeQGqaEm Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Monday 12 October 2015 14:30:39 Jongsung Kim wrote: > We tried to utilize a HW compressor as a zram backend. Current zram uses > kmap_atomic to map a page, and the HW DMAes. So we needed to use > kmap_atomic_to_page to get the page to be dma-mapped. How about changing the zcomp code to pass the page pointer instead of the kernel space pointer? That would avoid having to do the kmap_atomic, which can itself be expensive on 32-bit machines and should not be needed here if you have a HW DMA engine doing the compression. Arnd