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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3CA5AC25B4E for ; Fri, 20 Jan 2023 09:20:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229980AbjATJUI (ORCPT ); Fri, 20 Jan 2023 04:20:08 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34614 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230110AbjATJUF (ORCPT ); Fri, 20 Jan 2023 04:20:05 -0500 Received: from zeeaster.vergenet.net (zeeaster.vergenet.net [206.189.110.174]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 89F16420E for ; Fri, 20 Jan 2023 01:20:02 -0800 (PST) Received: from momiji.horms.nl (86-93-216-223.fixed.kpn.net [86.93.216.223]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by zeeaster.vergenet.net (Postfix) with ESMTPSA id EBCFE20095; Fri, 20 Jan 2023 09:02:53 +0000 (UTC) Received: by momiji.horms.nl (Postfix, from userid 7100) id 0E8C794030F; Fri, 20 Jan 2023 10:02:53 +0100 (CET) Date: Fri, 20 Jan 2023 10:02:52 +0100 From: Simon Horman To: Baoquan He Cc: linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-arm-kernel@lists.infradead.org, catalin.marinas@arm.com, will@kernel.org, thunder.leizhen@huawei.com, John.p.donnelly@oracle.com, wangkefeng.wang@huawei.com Subject: Re: [PATCH 2/2] arm64/kdump: add code comments for crashkernel reservation cases Message-ID: References: <20230117034921.185150-1-bhe@redhat.com> <20230117034921.185150-3-bhe@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230117034921.185150-3-bhe@redhat.com> Organisation: Horms Solutions BV X-Virus-Scanned: clamav-milter 0.103.7 at zeeaster X-Virus-Status: Clean Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 17, 2023 at 11:49:21AM +0800, Baoquan He wrote: > This will help understand codes on crashkernel reservations on arm64. FWIIW, I think you can fold this into the first patch. And, although I have no good idea at this moment, I do wonder if the logic can be simplified - I for one really needed the comments to understand the retry logic. > Signed-off-by: Baoquan He > --- > arch/arm64/mm/init.c | 13 +++++++++++++ > 1 file changed, 13 insertions(+) > > diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c > index 26a05af2bfa8..f88ad17cb20d 100644 > --- a/arch/arm64/mm/init.c > +++ b/arch/arm64/mm/init.c > @@ -177,6 +177,10 @@ static void __init reserve_crashkernel(void) > crash_base = memblock_phys_alloc_range(crash_size, CRASH_ALIGN, > search_base, crash_max); > if (!crash_base) { > + /* > + * For crashkernel=size[KMG]@offset[KMG], print out failure > + * message if can't reserve the specified region. > + */ > if (fixed_base) { > pr_warn("cannot reserve crashkernel region [0x%llx-0x%llx]\n", > search_base, crash_max); > @@ -188,6 +192,11 @@ static void __init reserve_crashkernel(void) > * high memory, the minimum required low memory will be > * reserved later. > */ > + /* > + * For crashkernel=size[KMG], if the first attempt was for > + * low memory, fall back to high memory, the minimum required > + * low memory will be reserved later. > + */ I think this duplicates the preceding comment. Perhaps just replace the earlier comment with this one. > if (!high && crash_max == CRASH_ADDR_LOW_MAX) { > crash_max = CRASH_ADDR_HIGH_MAX; > search_base = CRASH_ADDR_LOW_MAX; > @@ -195,6 +204,10 @@ static void __init reserve_crashkernel(void) > goto retry; > } > > + /* > + * For crashkernel=size[KMG],high, if the first attempt was for > + * high memory, fall back to low memory. > + */ > if (high && (crash_max == CRASH_ADDR_HIGH_MAX)) { > crash_max = CRASH_ADDR_LOW_MAX; > search_base = 0; > -- > 2.34.1 > > > _______________________________________________ > kexec mailing list > kexec@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/kexec >