From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752976AbbJMLoX (ORCPT ); Tue, 13 Oct 2015 07:44:23 -0400 Received: from mout.kundenserver.de ([212.227.126.187]:64475 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932190AbbJMLoV (ORCPT ); Tue, 13 Oct 2015 07:44:21 -0400 From: Arnd Bergmann To: Jongsung Kim Cc: linux-arm-kernel@lists.infradead.org, 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: Tue, 13 Oct 2015 13:44:09 +0200 Message-ID: <5510159.Ge1KiGjbaB@wuerfel> User-Agent: KMail/4.11.5 (Linux/3.16.0-10-generic; KDE/4.11.5; x86_64; ; ) In-Reply-To: <561C6734.7010509@lge.com> References: <1444129773-12632-1-git-send-email-chanho.min@lge.com> <5778996.I0Vmityi0g@wuerfel> <561C6734.7010509@lge.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" X-Provags-ID: V03:K0:1Map3pyynxayf+kw2a1REY+xEpyrVZLn4FrCMoxpmpHxGTBsN42 L/5dMvx0JRDhTCJY9XvFMuBstq4ZHnQIZJK5qI7PfuojAiMui0DqnLA62++MUEUGCGF5XGG 9sJhK96YpUccPnAJOMGtL2Op1/Xkx2oEwt6npYSx/CrphQ8KbllVyaAAHu7MabsP9d3syQm ErS7JgWzkh374c5Uh/CdA== X-UI-Out-Filterresults: notjunk:1;V01:K0:8TNdxA+n0Sg=:8nUMTa3gY81zNjy0fbpKUO ee+ag2Grdud2cBjTKChKhUGJTM3Lr9+eGQdDODeWbhMSh51+wvV/xwGbWMb4ZBr0b0XKyUrRS xJMWKB565WXPGpmy07612W0pE6Z+tJ2y0X7+40gcenqjaJw4AaREv3Yz4VVvQHVK9SC9ljS/V 6gYjewoGRGKUwbIIX19YICF5XzMxmPvtwRkuz2AxbS3nGtZAEBJjoBc0VDVmoJUKULMPxOlzb mmUcbmkAI/p2LOlX6mvbIB5pIlM6GkP+AJjNcrhBQ15oUFOTviXybHpqwcr9Ac0STFU/Qz/8J oJQyR5H1LBmTn2DwVjaK9YEASm2mt05pjKlbU2/Vd16OsB+1VJVY7qq3fGh0PzpdCai8+Qzq5 8VA+G4Hu4Z2DOcTZpDGAUTqZaSUory8hwOwX6lcy7s+/X4SsM+Q6q4UaKJFMGGA4cJyCk9hpb kIVBCx1s6LybCRMucUH76It0JO751U5/wXoQh4LYb1XjrfxI5CW3IHBRuMJAMXfkNa+3UV5sx xiDJDJ2fVTOszOYeHY+BqfvMXMV15TwSTpGBpUHuZnoW5DJqa0FcgsCpjZaBHMb/Wf/ejCMZV pWcB9eddljaoljS4KtrHz18/cjbBLI+Y6VXUmU1TrOT9pWCSNrxRrU8VeatHNrN2XrYUgll9Z AIOKkfoUAbDfKB88w3jfbiCyGC1pyKalVns+jjK2ZJOvtgnHxUcoZB2KyAJA3a33xfgquxJCH xYFe4g22KXUiqKHb Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday 13 October 2015 11:06:44 Jongsung Kim wrote: > On 10/12/2015 06:27 PM, Arnd Bergmann wrote: > > 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 > > Mainline zram uses lzo / lz4 library functions as backend. Using kmap_atomic and passing address look reasonable. Yes, I know, but changing this to do the kmap_atomic in the backend seems better here if you are adding another backend that doesn't want or need the kmap_atomic. Arnd