From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752722AbcGTCrS (ORCPT ); Tue, 19 Jul 2016 22:47:18 -0400 Received: from szxga02-in.huawei.com ([119.145.14.65]:64599 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752054AbcGTCrP (ORCPT ); Tue, 19 Jul 2016 22:47:15 -0400 Subject: Re: [PATCH 1/1] arm64/hugetlb: clear PG_dcache_clean if the page is dirty when munmap To: Catalin Marinas References: <1467893344-8352-1-git-send-email-thunder.leizhen@huawei.com> <20160707153741.GC27180@e104818-lin.cambridge.arm.com> <577F1FD9.1040205@huawei.com> <20160708135447.GB22099@e104818-lin.cambridge.arm.com> <577FC5AA.5010709@huawei.com> <20160708161347.GC22099@e104818-lin.cambridge.arm.com> <57839474.6030203@huawei.com> <20160712153535.GH22183@e104818-lin.cambridge.arm.com> CC: Steve Capper , David Woods , Tianhong Ding , Will Deacon , linux-kernel , Xinwei Hu , Zefan Li , Hanjun Guo , linux-arm-kernel From: "Leizhen (ThunderTown)" Message-ID: <578EE603.9020206@huawei.com> Date: Wed, 20 Jul 2016 10:46:27 +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: <20160712153535.GH22183@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=0001.0A090204.578EE610.0006,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0, ip=0.0.0.0, so=2013-06-18 04:22:30, dmn=2013-03-21 17:37:32 X-Mirapoint-Loop-Id: 852eeb0d2cf9728cad527fa79e9c3dbb Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2016/7/12 23:35, Catalin Marinas wrote: > On Mon, Jul 11, 2016 at 08:43:32PM +0800, Leizhen (ThunderTown) wrote: >> On 2016/7/9 0:13, Catalin Marinas wrote: >>> On Fri, Jul 08, 2016 at 11:24:26PM +0800, Leizhen (ThunderTown) 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<--------------------- Hi, Catalin: Do you plan to send this patch? My colleagues told me that if our patches are quite different, it should be Signed-off-by you. I searched all Linux source code, __sync_icache_dcache is only called by set_pte_at, and some check conditions(especially pte_exec) will limit its impact. if (pte_user(pte) && pte_exec(pte) && !pte_special(pte)) __sync_icache_dcache(pte, addr); >>>>> >>>>> BTW, can you make your tests (source) available somewhere? >>>> >>>> Both cases worked well with this patch. >>> >>> Now I'm even more confused ;). IIUC, after an msync() in user space we >>> should flush the pages to disk via write_cache_pages(). This function >>> calls clear_page_dirty_for_io() after which PageDirty() is no longer >>> true. I can't tell how a subsequent mmap() can see the written pages as >>> dirty. >> >> As my tracing, both cases invoked empty function. >> >> int vfs_fsync_range(struct file *file, loff_t start, loff_t end, int datasync) >> ...... >> return file->f_op->fsync(file, start, end, datasync); >> } >> >> const struct file_operations hugetlbfs_file_operations = { >> .fsync = noop_fsync, >> >> static const struct file_operations shmem_file_operations = { >> .mmap = shmem_mmap, >> #ifdef CONFIG_TMPFS >> .fsync = noop_fsync, > > I was referring to standard filesystem (e.g. ext4) writes where, IIUC, > the PageDirty() status is cleared after I/O but it's not necessarily > removed from the page cache. >