From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5EF34C433EF for ; Wed, 23 Mar 2022 13:59:47 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id DDDB16B0072; Wed, 23 Mar 2022 09:59:46 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D8D706B0073; Wed, 23 Mar 2022 09:59:46 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C574E6B0074; Wed, 23 Mar 2022 09:59:46 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0140.hostedemail.com [216.40.44.140]) by kanga.kvack.org (Postfix) with ESMTP id B83226B0072 for ; Wed, 23 Mar 2022 09:59:46 -0400 (EDT) Received: from smtpin31.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 76ABC99EB7 for ; Wed, 23 Mar 2022 13:59:46 +0000 (UTC) X-FDA: 79275809172.31.E0DB12E Received: from out30-130.freemail.mail.aliyun.com (out30-130.freemail.mail.aliyun.com [115.124.30.130]) by imf02.hostedemail.com (Postfix) with ESMTP id 45F988002D for ; Wed, 23 Mar 2022 13:59:43 +0000 (UTC) X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R191e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04394;MF=xiaoguang.wang@linux.alibaba.com;NM=1;PH=DS;RN=7;SR=0;TI=SMTPD_---0V80Be2u_1648043977; Received: from 30.225.28.175(mailfrom:xiaoguang.wang@linux.alibaba.com fp:SMTPD_---0V80Be2u_1648043977) by smtp.aliyun-inc.com(127.0.0.1); Wed, 23 Mar 2022 21:59:38 +0800 Message-ID: Date: Wed, 23 Mar 2022 21:59:37 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:91.0) Gecko/20100101 Thunderbird/91.7.0 Subject: Re: [RFC 2/3] mm: export zap_page_range() Content-Language: en-US To: David Hildenbrand , linux-mm@kvack.org, target-devel@vger.kernel.org, linux-scsi@vger.kernel.org Cc: linux-block@vger.kernel.org, xuyu@linux.alibaba.com, bostroesser@gmail.com References: <20220318095531.15479-1-xiaoguang.wang@linux.alibaba.com> <20220318095531.15479-3-xiaoguang.wang@linux.alibaba.com> <37d6b269-dd9d-dbd1-74b1-4191cc3d4bf9@linux.alibaba.com> <019a2159-57d6-c330-53c5-38458b6b5ec9@redhat.com> From: Xiaoguang Wang In-Reply-To: <019a2159-57d6-c330-53c5-38458b6b5ec9@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 45F988002D X-Stat-Signature: 83jm97a1bchp8pnbcsas49p96wgw67sf X-Rspam-User: Authentication-Results: imf02.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=alibaba.com; spf=pass (imf02.hostedemail.com: domain of xiaoguang.wang@linux.alibaba.com designates 115.124.30.130 as permitted sender) smtp.mailfrom=xiaoguang.wang@linux.alibaba.com X-HE-Tag: 1648043983-768691 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000117, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: hi, > On 22.03.22 14:02, Xiaoguang Wang wrote: >> hi, >> >>> On 18.03.22 10:55, Xiaoguang Wang wrote: >>>> Module target_core_user will use it to implement zero copy feature. >>>> >>>> Signed-off-by: Xiaoguang Wang >>>> --- >>>> mm/memory.c | 1 + >>>> 1 file changed, 1 insertion(+) >>>> >>>> diff --git a/mm/memory.c b/mm/memory.c >>>> index 1f745e4d11c2..9974d0406dad 100644 >>>> --- a/mm/memory.c >>>> +++ b/mm/memory.c >>>> @@ -1664,6 +1664,7 @@ void zap_page_range(struct vm_area_struct *vma, unsigned long start, >>>> mmu_notifier_invalidate_range_end(&range); >>>> tlb_finish_mmu(&tlb); >>>> } >>>> +EXPORT_SYMBOL_GPL(zap_page_range); >>>> >>>> /** >>>> * zap_page_range_single - remove user pages in a given range >>> To which VMAs will you be applying zap_page_range? I assume only to some >>> special ones where you previously vm_insert_page(s)_mkspecial'ed pages, >>> not to some otherwise random VMAs, correct? >> Yes, you're right :) > I'd suggest exposing a dedicated function that performs sanity checks on > the vma (VM_PFNMAP ?) and only zaps within a single VMA. > > Essentially zap_page_range_single(), excluding "struct zap_details > *details" and including sanity checks. > > Reason is that we don't want anybody to blindly zap_page_range() within > random VMAs from a kernel module. OK, I see, thanks. Xu Yu and I will try to implement a new helper in following new version patches. Regards, Xiaoguang Wang >