From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751816AbeAVSzV (ORCPT ); Mon, 22 Jan 2018 13:55:21 -0500 Received: from mail-wm0-f66.google.com ([74.125.82.66]:35548 "EHLO mail-wm0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751121AbeAVSzT (ORCPT ); Mon, 22 Jan 2018 13:55:19 -0500 X-Google-Smtp-Source: AH8x224GHmNbfX3pHQPCoZVSVjLmvxN7chnPn73oZ+oUKIGui0KOtubDa1oaPg0Lhtnw7nNZJiebb553rSeKzNWcPtc= MIME-Version: 1.0 In-Reply-To: References: <1515552545-18311-1-git-send-email-opensource.ganesh@gmail.com> <20180122155428.GB7714@kroah.com> From: =?UTF-8?B?QXJ2ZSBIasO4bm5ldsOlZw==?= Date: Mon, 22 Jan 2018 10:55:17 -0800 Message-ID: Subject: Re: [PATCH v3] android: binder: use VM_ALLOC to get vm area To: Todd Kjos Cc: Greg KH , Ganesh Mahendran , Martijn Coenen , LKML Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by mail.home.local id w0MItQlq021256 On Mon, Jan 22, 2018 at 9:02 AM, Todd Kjos wrote: > On Mon, Jan 22, 2018 at 7:54 AM, Greg KH wrote: >> On Wed, Jan 10, 2018 at 10:49:05AM +0800, Ganesh Mahendran wrote: >>> VM_IOREMAP is used to access hardware through a mechanism called >>> I/O mapped memory. Android binder is a IPC machanism which will >>> not access I/O memory. >>> >>> And VM_IOREMAP has alignment requiement which may not needed in >>> binder. >>> __get_vm_area_node() >>> { >>> ... >>> if (flags & VM_IOREMAP) >>> align = 1ul << clamp_t(int, fls_long(size), >>> PAGE_SHIFT, IOREMAP_MAX_ORDER); >>> ... >>> } >>> >>> This patch will save some kernel vm area, especially for 32bit os. >>> >>> In 32bit OS, kernel vm area is only 240MB. We may got below >>> error when launching a app: >>> >>> <3>[ 4482.440053] binder_alloc: binder_alloc_mmap_handler: 15728 8ce67000-8cf65000 get_vm_area failed -12 >>> <3>[ 4483.218817] binder_alloc: binder_alloc_mmap_handler: 15745 8ce67000-8cf65000 get_vm_area failed -12 >>> >>> Signed-off-by: Ganesh Mahendran >>> ---- >>> V3: update comments >>> V2: update comments >>> --- >>> drivers/android/binder_alloc.c | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> Martijn and Todd, any objections to this patch? > > Looks fine to me. Arve, do you remember the rationale for using VM_IOREMAP? > I don't remember for sure, but I think it used alloc_vm_area at some point, and that uses VM_IOREMAP. -- Arve Hjønnevåg