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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 81983C36008 for ; Wed, 26 Mar 2025 11:29:02 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 9E61F280074; Wed, 26 Mar 2025 07:29:00 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 99891280069; Wed, 26 Mar 2025 07:29:00 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 85F30280074; Wed, 26 Mar 2025 07:29:00 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id 69009280069 for ; Wed, 26 Mar 2025 07:29:00 -0400 (EDT) Received: from smtpin18.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 1C40712148B for ; Wed, 26 Mar 2025 11:29:01 +0000 (UTC) X-FDA: 83263480482.18.6C01279 Received: from nyc.source.kernel.org (nyc.source.kernel.org [147.75.193.91]) by imf17.hostedemail.com (Postfix) with ESMTP id 6D6F040006 for ; Wed, 26 Mar 2025 11:28:59 +0000 (UTC) Authentication-Results: imf17.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=dO+wudTy; spf=pass (imf17.hostedemail.com: domain of rppt@kernel.org designates 147.75.193.91 as permitted sender) smtp.mailfrom=rppt@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1742988539; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=q7gIiSkBn+7zXAPWwwqnDBEsrDXMe6gcX/DYFPbvGnw=; b=z74/StfQsEHvlexhA28BoVlSqw7HQKW8XsdKGdKfH0mbCsGcOs8sqe6uxaOJAGS5lim7E4 8aXinfsKHNfJuSYyCJYrFk8gAYpaSvJatN9iANftAY02CkKuq2eRZkE2c1LnQ62DWQ1lce L1Rx7Lhbc5U5MyM9Ilce6pXrFZyYBhk= ARC-Authentication-Results: i=1; imf17.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=dO+wudTy; spf=pass (imf17.hostedemail.com: domain of rppt@kernel.org designates 147.75.193.91 as permitted sender) smtp.mailfrom=rppt@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1742988539; a=rsa-sha256; cv=none; b=M1aYR7ThbR9k56Wwwf7TV63XjpRi9J5f2dk1N3Xbuf4Rui16j1PgydLyUGkdLoNp5wSs+j IjCTJo25J9goVCG35V9wMQsKNSndXdPzuHbBiuqKv0aavT49k+IrupR6KYMUQWRhWevJQ4 1iCtUgX00MTiL3pN2DNFaJW7wPA2cc0= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by nyc.source.kernel.org (Postfix) with ESMTP id 5CFFBA41083; Wed, 26 Mar 2025 11:23:29 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 82D4CC4CEEA; Wed, 26 Mar 2025 11:28:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1742988538; bh=4Sh1ikImfk7eyob7pJYLP87Gp+VBMFoDyKt80LgWr+w=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=dO+wudTy752jbZBiKbEzH/y7kZltbC12thCjkIvnZenkEwF5D2goiKObY33+DZByK 62goXNL37ZMBjPsOFTzt1itoLJjbfI4q2kHo+gcavcD8Ed+ocOY+Elo0yUuq/RzkD4 FOqbHWsKAMpikkVh2I3TcWSLtiluyof3uUc5RxuLdFK2gbkm+vCt964jw4Ou0EI2Iy SJHfXybHBPCt7535DKZ9pCxr1axSlbqbsF7nsodCCYZDBGsbw1rDAozoM+sEo3H3k5 40tkPnOq6VoCDvDqRAzPP/4s0qs6uIS8Ba3o5wFBmsURz9VrW0qQnuUQ5iLdNYoEuu YHaiM9Fkt9Z/A== Date: Wed, 26 Mar 2025 07:28:52 -0400 From: Mike Rapoport To: Dave Young Cc: Baoquan He , Changyuan Lyu , linux-kernel@vger.kernel.org, graf@amazon.com, akpm@linux-foundation.org, luto@kernel.org, anthony.yznaga@oracle.com, arnd@arndb.de, ashish.kalra@amd.com, benh@kernel.crashing.org, bp@alien8.de, catalin.marinas@arm.com, dave.hansen@linux.intel.com, dwmw2@infradead.org, ebiederm@xmission.com, mingo@redhat.com, jgowans@amazon.com, corbet@lwn.net, krzk@kernel.org, mark.rutland@arm.com, pbonzini@redhat.com, pasha.tatashin@soleen.com, hpa@zytor.com, peterz@infradead.org, ptyadav@amazon.de, robh+dt@kernel.org, robh@kernel.org, saravanak@google.com, skinsburskii@linux.microsoft.com, rostedt@goodmis.org, tglx@linutronix.de, thomas.lendacky@amd.com, usama.arif@bytedance.com, will@kernel.org, devicetree@vger.kernel.org, kexec@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, x86@kernel.org Subject: Re: [PATCH v5 11/16] kexec: add config option for KHO Message-ID: References: <20250320015551.2157511-1-changyuanl@google.com> <20250320015551.2157511-12-changyuanl@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: 6D6F040006 X-Rspamd-Server: rspam05 X-Rspam-User: X-Stat-Signature: n9z3icatkemmp3omi459n7qjixijdmrd X-HE-Tag: 1742988539-444779 X-HE-Meta: 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 w5tDw51B x+rIceMqexI39NHdJoRLxwlcuntwSRAjlMS7BjAtT1mFphap9uCAOYC+nhTWXItUPeb5mZXUZfUWO4+l2HMR+dlXc/aj4h85/sY+RgLnCCty+E0obXDiIKw4tTk6LuJOhHLcPYcFoOjZsxPBCZQ45sjLyLJzncEUHKB/Fm/UpIHjoHmSPKe4JGystIwNSid+5C1kdTdgVWo9WqC3bSvd9y9A7uy0S7zeH1B3o6fztgUnfsho0A+5l4GjC5ZdcagBFhlKUCqoL+GJYw6t+W3WtMPROoEziDuxWwHz6hyp8v1wmNF283Zj6CHBoJMQFivJmT2VFvtpTDlzlVSVTEB5QL/Mx4okfHv6Nc5rJQ4vfIeWoi9VVNCwA+MFrKw== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hi Dave, On Wed, Mar 26, 2025 at 05:17:16PM +0800, Dave Young wrote: > On Tue, 25 Mar 2025 at 16:36, Dave Young wrote: > > > > > > > > > > Have you tested kdump? In my mind there are two issues, one is with > > > > CMA enabled, it could cause kdump crashkernel memory reservation > > > > failures more often due to the fragmented low memory. Secondly, in > > > > > > kho scracth memorys are reserved much later than crashkernel, we may not > > > need to worry about it. > > > ==================== > > > start_kernel() > > > ...... > > > -->setup_arch(&command_line); > > > -->arch_reserve_crashkernel(); > > > ...... > > > -->mm_core_init(); > > > -->kho_memory_init(); > > > > > > > kdump kernel dump the crazy scratch memory in vmcore is not very > > > > meaningful. Otherwise I suspect this is not tested under kdump. If > > > > so please disable this option for kdump. > > > > Ok, it is fine if this is the case, thanks Baoquan for clearing this worry. > > > > But the other concerns are still need to address, eg. KHO use cases > > are not good for kdump. > > There could be more to think about. > > eg. the issues talked in thread: > > https://lore.kernel.org/lkml/Z7dc9Cd8KX3b_brB@dwarf.suse.cz/T/ > > Rethink about this, other than previous concerns. Transferring the > old kernel state to kdump kernel makes no sense since the old state is > not stable as the kernel has crashed. KHO won't be active for kdump case. The KHO segments are only added to kexec_image and never to kexec_crash_image. -- Sincerely yours, Mike.