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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id AB5FFC3DA4A for ; Fri, 9 Aug 2024 09:52:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=Y8weYdPg7JNMXMjy0iRii8Bu7sAXHTQVsrxzPV8dUZs=; b=CQVbnzXIUtFWbM548dgCANAqOY EioSg5haiRLIkREF+9smn/rPSkB/O9+xbFRwPOJj5UqcI3AEPcMCFy3hd8NOmuPmrKh2ZEDgIWtMM PGy82Kx86RaqxG6X0DoJ4HxcfnTXklwc5xrU8oP+wqy9szeVU/cplNmTfDNMVLoCEAzZRrqKbZcAQ Y0m6re9nUKbgPbHQV/9QJSfJR3idXuD2WGmzW3x2pcniTsHJ9hTllwJbKxnGkk1X4Dwy6isKHTM3j OgUEtK4ZzCLn0Dq78SoF/FhefNmixqFzp5Iae29YZmnLJMQUKjN9EoO/mXv7qbGeq0qcjtKABKR4/ Y75lELqg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1scMIK-0000000As8d-1J1f; Fri, 09 Aug 2024 09:52:24 +0000 Received: from sin.source.kernel.org ([2604:1380:40e1:4800::1]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1scMHj-0000000As25-20wZ; Fri, 09 Aug 2024 09:51:49 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sin.source.kernel.org (Postfix) with ESMTP id 18E1CCE130A; Fri, 9 Aug 2024 09:51:45 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B8185C4AF0D; Fri, 9 Aug 2024 09:51:41 +0000 (UTC) Date: Fri, 9 Aug 2024 10:51:39 +0100 From: Catalin Marinas To: Jinjie Ruan Cc: Baoquan He , vgoyal@redhat.com, dyoung@redhat.com, paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, chenjiahao16@huawei.com, akpm@linux-foundation.org, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, linux-arm-kernel@lists.infradead.org, Will Deacon Subject: Re: [PATCH -next] crash: Fix riscv64 crash memory reserve dead loop Message-ID: References: <20240802090105.3871929-1-ruanjinjie@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240809_025147_975648_6734E789 X-CRM114-Status: GOOD ( 29.90 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Aug 08, 2024 at 03:56:35PM +0800, Jinjie Ruan wrote: > On 2024/8/7 3:34, Catalin Marinas wrote: > > On Tue, Aug 06, 2024 at 08:10:30PM +0100, Catalin Marinas wrote: > >> On Fri, Aug 02, 2024 at 06:11:01PM +0800, Baoquan He wrote: > >>> And I don't like the idea crashkernel=,high failure will fallback to > >>> attempt in low area, so this looks good to me. > >> > >> Well, I kind of liked this behaviour. One can specify ,high as a > >> preference rather than forcing a range. The arm64 land has different > >> platforms with some constrained memory layouts. Such fallback works well > >> as a default command line option shipped with distros without having to > >> guess the SoC memory layout. > > > > I haven't tried but it's possible that this patch also breaks those > > arm64 platforms with all RAM above 4GB when CRASH_ADDR_LOW_MAX is > > memblock_end_of_DRAM(). Here all memory would be low and in the absence > > of no fallback, it fails to allocate. > > > > So, my strong preference would be to re-instate the current behaviour > > and work around the infinite loop in a different way. > > Hi, baoquan, What's your opinion? > > Only this patch should be re-instate or all the 3 dead loop fix patch? Only the riscv64 patch that that removes the ,high reservation fallback to ,low. From this series: https://lore.kernel.org/r/20240719095735.1912878-1-ruanjinjie@huawei.com/ the first two fixes look fine (x86_32). The third one (arm32), not sure why it's in the series called "crash: Fix x86_32 memory reserve dead loop bug". Does it fix a problem on arm32? Anyway, I'm not against it getting merged but I'm not maintaining arm32. If the first two patches could be merged for 6.11, I think the arm32 one is more of a 6.12 material (unless it does fix something). On the riscv64 patch removing the high->low fallback to avoid the infinite loop, I'd rather replace it with something similar to the x86_32 fix in the series above. I suggested something in the main if block but, looking at the x86_32 fix, for consistency, I think it would look better as something like: diff --git a/kernel/crash_reserve.c b/kernel/crash_reserve.c index d3b4cd12bdd1..64d44a52c011 100644 --- a/kernel/crash_reserve.c +++ b/kernel/crash_reserve.c @@ -423,7 +423,8 @@ void __init reserve_crashkernel_generic(char *cmdline, if (high && search_end == CRASH_ADDR_HIGH_MAX) { search_end = CRASH_ADDR_LOW_MAX; search_base = 0; - goto retry; + if (search_end != CRASH_ADDR_HIGH_MAX) + goto retry; } pr_warn("cannot allocate crashkernel (size:0x%llx)\n", crash_size); In summary, just replace the riscv64 fix with something along the lines of the diff above (or pick whatever you prefer that still keeps the fallback). Thanks. -- Catalin