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 85228C52D7C for ; Mon, 12 Aug 2024 10:40:48 +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=wv3SavuVNL+mlfOSIM5zaKRPR7DBxMTBmoFc+JBuD8I=; b=gOhQCvWQ7UplcIokF8fdKTYUlK UzSvGX2hNohHAPbzikqXOFU5sFxv2uq/G4fc2X051eAY9uCn/rwNzU6JlNtcWnVB28IXH3Z5CBCLE mnsyzjx0W+swvsjWE/+hY7EOXAo0zMVlzV2sPfDVKn9ow3wQIAZeZz15WFZhroHbnLPIL2cHrvgut jLFzXqIZnX79856ZBBjqSW62bhsMVpvTTtm6BA+ciEwa707ElOPJF3WCLxx6FerElhlOtoiKg/5Ey aEPDf+eX09DcNlLWVQ4BNpYbXK09uwFTxW8g4xfHSQEEk9opQ3PS5mRmyIHh+Subo/k3e4gSTe1Yz 9fWkK4Dg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1sdSTf-000000003ff-3g0S; Mon, 12 Aug 2024 10:40:39 +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 1sdST2-000000003Rs-0lyn; Mon, 12 Aug 2024 10:40:01 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sin.source.kernel.org (Postfix) with ESMTP id 169E6CE0B27; Mon, 12 Aug 2024 10:39:58 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C5A66C32782; Mon, 12 Aug 2024 10:39:54 +0000 (UTC) Date: Mon, 12 Aug 2024 11:39:52 +0100 From: Catalin Marinas To: Jinjie Ruan Cc: bhe@redhat.com, vgoyal@redhat.com, dyoung@redhat.com, paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-riscv@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-arch@vger.kernel.org Subject: Re: [PATCH -next v2] crash: Fix riscv64 crash memory reserve dead loop Message-ID: References: <20240812062017.2674441-1-ruanjinjie@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240812062017.2674441-1-ruanjinjie@huawei.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240812_034000_414981_700C0C2E X-CRM114-Status: GOOD ( 13.54 ) 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 Mon, Aug 12, 2024 at 02:20:17PM +0800, Jinjie Ruan wrote: > On RISCV64 Qemu machine with 512MB memory, cmdline "crashkernel=500M,high" > will cause system stall as below: > > Zone ranges: > DMA32 [mem 0x0000000080000000-0x000000009fffffff] > Normal empty > Movable zone start for each node > Early memory node ranges > node 0: [mem 0x0000000080000000-0x000000008005ffff] > node 0: [mem 0x0000000080060000-0x000000009fffffff] > Initmem setup node 0 [mem 0x0000000080000000-0x000000009fffffff] > (stall here) > > commit 5d99cadf1568 ("crash: fix x86_32 crash memory reserve dead loop > bug") fix this on 32-bit architecture. However, the problem is not > completely solved. If `CRASH_ADDR_LOW_MAX = CRASH_ADDR_HIGH_MAX` on 64-bit > architecture, for example, when system memory is equal to > CRASH_ADDR_LOW_MAX on RISCV64, the following infinite loop will also occur: > > -> reserve_crashkernel_generic() and high is true > -> alloc at [CRASH_ADDR_LOW_MAX, CRASH_ADDR_HIGH_MAX] fail > -> alloc at [0, CRASH_ADDR_LOW_MAX] fail and repeatedly > (because CRASH_ADDR_LOW_MAX = CRASH_ADDR_HIGH_MAX). > > As Catalin suggested, do not remove the ",high" reservation fallback to > ",low" logic which will change arm64's kdump behavior, but fix it by > skipping the above situation similar to commit d2f32f23190b ("crash: fix > x86_32 crash memory reserve dead loop"). > > After this patch, it print: > cannot allocate crashkernel (size:0x1f400000) > > Signed-off-by: Jinjie Ruan > Suggested-by: Catalin Marinas Reviewed-by: Catalin Marinas Thanks.