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=-11.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SIGNED_OFF_BY,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 8F241C4727D for ; Thu, 24 Sep 2020 03:24:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6487D23600 for ; Thu, 24 Sep 2020 03:24:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727019AbgIXDY3 (ORCPT ); Wed, 23 Sep 2020 23:24:29 -0400 Received: from foss.arm.com ([217.140.110.172]:32968 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726634AbgIXDY0 (ORCPT ); Wed, 23 Sep 2020 23:24:26 -0400 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 3267A113E; Wed, 23 Sep 2020 20:24:25 -0700 (PDT) Received: from [10.163.75.147] (unknown [10.163.75.147]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 636583F73B; Wed, 23 Sep 2020 20:24:22 -0700 (PDT) From: Anshuman Khandual Subject: Re: [PATCH V3 1/3] arm64/mm/hotplug: Register boot memory hot remove notifier earlier To: Gavin Shan , linux-arm-kernel@lists.infradead.org Cc: Mark Rutland , Will Deacon , catalin.marinas@arm.com, Steve Capper , linux-kernel@vger.kernel.org, Mark Brown , Marc Zyngier , will@kernel.org References: <1600689908-28213-1-git-send-email-anshuman.khandual@arm.com> <1600689908-28213-2-git-send-email-anshuman.khandual@arm.com> Message-ID: Date: Thu, 24 Sep 2020 08:53:47 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/23/2020 11:34 AM, Gavin Shan wrote: > Hi Anshuman, > > On 9/21/20 10:05 PM, Anshuman Khandual wrote: >> This moves memory notifier registration earlier in the boot process from >> device_initcall() to early_initcall() which will help in guarding against >> potential early boot memory offline requests. Even though there should not >> be any actual offlinig requests till memory block devices are initialized >> with memory_dev_init() but then generic init sequence might just change in >> future. Hence an early registration for the memory event notifier would be >> helpful. While here, just skip the registration if CONFIG_MEMORY_HOTREMOVE >> is not enabled and also call out when memory notifier registration fails. >> >> Cc: Catalin Marinas >> Cc: Will Deacon >> Cc: Mark Rutland >> Cc: Marc Zyngier >> Cc: Steve Capper >> Cc: Mark Brown >> Cc: linux-arm-kernel@lists.infradead.org >> Cc: linux-kernel@vger.kernel.org >> Signed-off-by: Anshuman Khandual >> --- >>   arch/arm64/mm/mmu.c | 14 ++++++++++++-- >>   1 file changed, 12 insertions(+), 2 deletions(-) >> > > With the following nit-picky comments resolved: > > Reviewed-by: Gavin Shan > >> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c >> index 75df62fea1b6..df3b7415b128 100644 >> --- a/arch/arm64/mm/mmu.c >> +++ b/arch/arm64/mm/mmu.c >> @@ -1499,7 +1499,17 @@ static struct notifier_block prevent_bootmem_remove_nb = { >>     static int __init prevent_bootmem_remove_init(void) >>   { >> -    return register_memory_notifier(&prevent_bootmem_remove_nb); >> +    int ret = 0; >> + >> +    if (!IS_ENABLED(CONFIG_MEMORY_HOTREMOVE)) >> +        return ret; >> + >> +    ret = register_memory_notifier(&prevent_bootmem_remove_nb); >> +    if (!ret) >> +        return ret; >> + >> +    pr_err("Notifier registration failed - boot memory can be removed\n"); >> +    return ret; >>   } > > It might be cleaner if the duplicated return statements can be > avoided. Besides, it's always nice to print the errno even though Thought about it, just that the error message was too long. > zero is always returned from register_memory_notifier(). So I guess > you probably need something like below: > >         ret = register_memory_notifier(&prevent_bootmem_remove_nb); >         if (ret) >             pr_err("%s: Error %d registering notifier\n", __func__, ret) > >         return ret; Sure, will do. > > > register_memory_notifier                   # 0 is returned on !CONFIG_MEMORY_HOTPLUG_SPARSE >    blocking_notifier_chain_register >       notifier_chain_register              # 0 is always returned >       >> -device_initcall(prevent_bootmem_remove_init); >> +early_initcall(prevent_bootmem_remove_init); >>   #endif >> > > Cheers, > Gavin > >