From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lb0-f176.google.com (mail-lb0-f176.google.com [209.85.217.176]) by kanga.kvack.org (Postfix) with ESMTP id 6E2E16B0038 for ; Tue, 16 Jun 2015 03:15:28 -0400 (EDT) Received: by lbbqq2 with SMTP id qq2so4818893lbb.3 for ; Tue, 16 Jun 2015 00:15:27 -0700 (PDT) Received: from mail-wi0-x230.google.com (mail-wi0-x230.google.com. [2a00:1450:400c:c05::230]) by mx.google.com with ESMTPS id bu10si247351wjc.55.2015.06.16.00.15.26 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 16 Jun 2015 00:15:26 -0700 (PDT) Received: by wigg3 with SMTP id g3so99575784wig.1 for ; Tue, 16 Jun 2015 00:15:25 -0700 (PDT) Date: Tue, 16 Jun 2015 09:15:23 +0200 From: Pali =?utf-8?B?Um9ow6Fy?= Subject: Re: Possible broken MM code in dell-laptop.c? Message-ID: <20150616071523.GB5863@pali> References: <201506141105.07171@pali> <20150615211816.GC16138@dhcp22.suse.cz> <201506152327.59907@pali> <20150616063346.GA24296@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20150616063346.GA24296@dhcp22.suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko , Darren Hart Cc: Hans de Goede , Ben Skeggs , Stuart Hayes , Matthew Garrett , Andrew Morton , platform-driver-x86@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org On Tuesday 16 June 2015 08:33:46 Michal Hocko wrote: > On Mon 15-06-15 23:27:59, Pali RohA!r wrote: > > On Monday 15 June 2015 23:18:16 Michal Hocko wrote: > > > On Sun 14-06-15 11:05:07, Pali RohA!r wrote: > > > > Hello, > > > > > > > > in drivers/platform/x86/dell-laptop.c is this part of code: > > > > > > > > static int __init dell_init(void) > > > > { > > > > ... > > > > > > > > /* > > > > > > > > * Allocate buffer below 4GB for SMI data--only 32-bit physical > > > > addr * is passed to SMI handler. > > > > */ > > > > > > > > bufferpage = alloc_page(GFP_KERNEL | GFP_DMA32); > > > > > > [...] > > > > > > > buffer = page_address(bufferpage); > > > > > > [...] > > > > > > > fail_rfkill: > > > > free_page((unsigned long)bufferpage); > > > > > > This one should be __free_page because it consumes struct page* and > > > it is the proper counter part for alloc_page. free_page, just to > > > make it confusing, consumes an address which has to be translated to > > > a struct page. > > > > > > I have no idea why the API has been done this way and yeah, it is > > > really confusing. > > > > > > [...] > > > > > > > static void __exit dell_exit(void) > > > > { > > > > ... > > > > > > > > free_page((unsigned long)buffer); > > > > So both, either: > > > > free_page((unsigned long)buffer); > > > > or > > > > __free_page(bufferpage); > > > > is correct? > > Yes. Although I would use __free_page variant as both seem to be > globally visible. > Michal, thank you for explaining this situation! Darren, I will prepare patch which will fix code and use __free_page(). (Btw, execution on fail_rfkill label caused kernel panic) -- Pali RohA!r pali.rohar@gmail.com -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org