From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758598AbcHYLdS (ORCPT ); Thu, 25 Aug 2016 07:33:18 -0400 Received: from szxga03-in.huawei.com ([119.145.14.66]:25127 "EHLO szxga03-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758114AbcHYLdQ (ORCPT ); Thu, 25 Aug 2016 07:33:16 -0400 Subject: Re: [PATCH 1/1] arm64/hugetlb: clear PG_dcache_clean if the page is dirty when munmap To: Catalin Marinas References: <20160708161347.GC22099@e104818-lin.cambridge.arm.com> <57839474.6030203@huawei.com> <20160712153535.GH22183@e104818-lin.cambridge.arm.com> <578EE603.9020206@huawei.com> <20160720091939.GA25890@e104818-lin.cambridge.arm.com> <57BA7D38.8030103@huawei.com> <20160823172852.GB16213@e104818-lin.cambridge.arm.com> <57BD6242.1080801@huawei.com> <20160824103044.GA11504@e104818-lin.cambridge.arm.com> <57BE4D02.1040906@huawei.com> <20160825093054.GB20748@e104818-lin.cambridge.arm.com> CC: Steve Capper , David Woods , Tianhong Ding , Will Deacon , linux-kernel , Xinwei Hu , Zefan Li , "fangwei (I)" , "Hanjun Guo" , linux-arm-kernel , wangxuefeng 00195527 From: "Leizhen (ThunderTown)" Message-ID: <57BED633.1060802@huawei.com> Date: Thu, 25 Aug 2016 19:27:47 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.5.1 MIME-Version: 1.0 In-Reply-To: <20160825093054.GB20748@e104818-lin.cambridge.arm.com> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.177.23.164] X-CFilter-Loop: Reflected X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A020201.57BED725.0164,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0, ip=0.0.0.0, so=2013-05-26 15:14:31, dmn=2013-03-21 17:37:32 X-Mirapoint-Loop-Id: db3e58e7860276473dd333901f1acfc7 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2016/8/25 17:30, Catalin Marinas wrote: > On Thu, Aug 25, 2016 at 09:42:26AM +0800, Leizhen (ThunderTown) wrote: >> On 2016/8/24 18:30, Catalin Marinas wrote: >>>>>>>>>>>> On 2016/7/8 21:54, Catalin Marinas wrote: >>>>>>>>>>>>> ------------8<---------------- >>>>>>>>>>>>> diff --git a/arch/arm64/mm/flush.c b/arch/arm64/mm/flush.c >>>>>>>>>>>>> index dbd12ea8ce68..c753fa804165 100644 >>>>>>>>>>>>> --- a/arch/arm64/mm/flush.c >>>>>>>>>>>>> +++ b/arch/arm64/mm/flush.c >>>>>>>>>>>>> @@ -75,7 +75,8 @@ void __sync_icache_dcache(pte_t pte, unsigned long addr) >>>>>>>>>>>>> if (!page_mapping(page)) >>>>>>>>>>>>> return; >>>>>>>>>>>>> >>>>>>>>>>>>> - if (!test_and_set_bit(PG_dcache_clean, &page->flags)) >>>>>>>>>>>>> + if (!test_and_set_bit(PG_dcache_clean, &page->flags) || >>>>>>>>>>>>> + PageDirty(page)) >>>>>>>>>>>>> sync_icache_aliases(page_address(page), >>>>>>>>>>>>> PAGE_SIZE << compound_order(page)); >>>>>>>>>>>>> else if (icache_is_aivivt()) >>>>>>>>>>>>> ----------------8<--------------------- > [...] >>> While we indeed see failures on multiple filesystem types, I wonder >>> whether this test case is actually expected to work. If I modify the >>> test to pass O_TRUNC to open(), I can no longer see failures. So any >>> standard tool that copies/creates executable files (gcc, dpkg, cp, rsync >>> etc.) wouldn't encounter such issues since they truncate the original >>> file and old page cache pages would be removed. >>> >>> Do you have a real use-case where a task mmap's an executable file, >>> modifies it in place and expects another task to see the new >>> instructions without user-space cache maintenance? >> >> No, it's just a test case created by testers. > > In this case I propose we ignore this patch and you adjust the test to > use O_TRUNC, at least until we find a real scenario where this would > matter. OK, thanks. We currently add __clear_cache in user space. >