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 X-Spam-Level: X-Spam-Status: No, score=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0081AC64E7C for ; Thu, 3 Dec 2020 00:33:12 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 5601E221F7 for ; Thu, 3 Dec 2020 00:33:11 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5601E221F7 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 534F06B005C; Wed, 2 Dec 2020 19:33:10 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 4E46F6B005D; Wed, 2 Dec 2020 19:33:10 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3FA8A6B0068; Wed, 2 Dec 2020 19:33:10 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0183.hostedemail.com [216.40.44.183]) by kanga.kvack.org (Postfix) with ESMTP id 2570B6B005C for ; Wed, 2 Dec 2020 19:33:10 -0500 (EST) Received: from smtpin02.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id DF3FB3637 for ; Thu, 3 Dec 2020 00:33:09 +0000 (UTC) X-FDA: 77550096498.02.ant44_0e14053273b7 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin02.hostedemail.com (Postfix) with ESMTP id C02F510097AA0 for ; Thu, 3 Dec 2020 00:33:09 +0000 (UTC) X-HE-Tag: ant44_0e14053273b7 X-Filterd-Recvd-Size: 4429 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf13.hostedemail.com (Postfix) with ESMTP for ; Thu, 3 Dec 2020 00:33:09 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 767BA113E; Wed, 2 Dec 2020 16:33:08 -0800 (PST) Received: from [192.168.0.130] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 29EA03F575; Wed, 2 Dec 2020 16:33:05 -0800 (PST) Subject: Re: [RFC V2 3/3] s390/mm: Define arch_get_mappable_range() To: Heiko Carstens Cc: linux-mm@kvack.org, akpm@linux-foundation.org, david@redhat.com, linux-arm-kernel@lists.infradead.org, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, Vasily Gorbik References: <1606706992-26656-1-git-send-email-anshuman.khandual@arm.com> <1606706992-26656-4-git-send-email-anshuman.khandual@arm.com> <20201202203233.GB11274@osiris> From: Anshuman Khandual Message-ID: <24905c32-f6c1-97a0-000f-f822b9870ea5@arm.com> Date: Thu, 3 Dec 2020 06:03:00 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20201202203233.GB11274@osiris> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Bogosity: Ham, tests=bogofilter, spamicity=0.000001, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 12/3/20 2:02 AM, Heiko Carstens wrote: > On Mon, Nov 30, 2020 at 08:59:52AM +0530, Anshuman Khandual wrote: >> This overrides arch_get_mappabble_range() on s390 platform and drops now >> redundant similar check in vmem_add_mapping(). This compensates by adding >> a new check __segment_load() to preserve the existing functionality. >> >> Cc: Heiko Carstens >> Cc: Vasily Gorbik >> Cc: David Hildenbrand >> Cc: linux-s390@vger.kernel.org >> Cc: linux-kernel@vger.kernel.org >> Signed-off-by: Anshuman Khandual >> --- >> arch/s390/mm/extmem.c | 5 +++++ >> arch/s390/mm/vmem.c | 13 +++++++++---- >> 2 files changed, 14 insertions(+), 4 deletions(-) >> >> diff --git a/arch/s390/mm/extmem.c b/arch/s390/mm/extmem.c >> index 5060956b8e7d..cc055a78f7b6 100644 >> --- a/arch/s390/mm/extmem.c >> +++ b/arch/s390/mm/extmem.c >> @@ -337,6 +337,11 @@ __segment_load (char *name, int do_nonshared, unsigned long *addr, unsigned long >> goto out_free_resource; >> } >> >> + if (seg->end + 1 > VMEM_MAX_PHYS || seg->end + 1 < seg->start_addr) { >> + rc = -ERANGE; >> + goto out_resource; >> + } >> + >> rc = vmem_add_mapping(seg->start_addr, seg->end - seg->start_addr + 1); >> if (rc) >> goto out_resource; >> diff --git a/arch/s390/mm/vmem.c b/arch/s390/mm/vmem.c >> index b239f2ba93b0..06dddcc0ce06 100644 >> --- a/arch/s390/mm/vmem.c >> +++ b/arch/s390/mm/vmem.c >> @@ -532,14 +532,19 @@ void vmem_remove_mapping(unsigned long start, unsigned long size) >> mutex_unlock(&vmem_mutex); >> } >> >> +struct range arch_get_mappable_range(void) >> +{ >> + struct range memhp_range; >> + >> + memhp_range.start = 0; >> + memhp_range.end = VMEM_MAX_PHYS; >> + return memhp_range; >> +} >> + >> int vmem_add_mapping(unsigned long start, unsigned long size) >> { >> int ret; >> >> - if (start + size > VMEM_MAX_PHYS || >> - start + size < start) >> - return -ERANGE; >> - > > I really fail to see how this could be considered an improvement for > s390. Especially I do not like that the (central) range check is now > moved to the caller (__segment_load). Which would mean potential > additional future callers would have to duplicate that code as well. The physical range check is being moved to the generic hotplug code via arch_get_mappable_range() instead, making the existing check in vmem_add_mapping() redundant. Dropping the check there necessitates adding back a similar check in __segment_load(). Otherwise there will be a loss of functionality in terms of range check. May be we could just keep this existing check in vmem_add_mapping() as well in order avoid this movement but then it would be redundant check in every hotplug path. So I guess the choice is to either have redundant range checks in all hotplug paths or future internal callers of vmem_add_mapping() take care of the range check.