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 F383FC433FE for ; Tue, 1 Nov 2022 17:58:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229766AbiKAR6K (ORCPT ); Tue, 1 Nov 2022 13:58:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50170 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229531AbiKAR6G (ORCPT ); Tue, 1 Nov 2022 13:58:06 -0400 Received: from out1-smtp.messagingengine.com (out1-smtp.messagingengine.com [66.111.4.25]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8358E1CB1C for ; Tue, 1 Nov 2022 10:58:05 -0700 (PDT) Received: from compute3.internal (compute3.nyi.internal [10.202.2.43]) by mailout.nyi.internal (Postfix) with ESMTP id E2BE45C00B4; Tue, 1 Nov 2022 13:58:02 -0400 (EDT) Received: from imap51 ([10.202.2.101]) by compute3.internal (MEProxy); Tue, 01 Nov 2022 13:58:02 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=arndb.de; h=cc :cc:content-type:date:date:from:from:in-reply-to:in-reply-to :message-id:mime-version:references:reply-to:sender:subject :subject:to:to; s=fm3; t=1667325482; x=1667411882; bh=A6U+kzuhbp V6DCjZ72Q29RzpIC4msYQyaXKxULxy43U=; b=W3KaahBKJDAuy2s0T2smBIL3Nu GvmDbAq4YfNCHkrw+Ip1+Fl+PAtBrCCxfeG4r04mSf/CZkGFUy6LR5Q87Xq66bCs HuDa24osi284FkwXY7BL8NQP6dsP6FZN7c7Yc6GSOV+COwh6ETsAnrNMlmwPc/xX V14ktLMuIv+a6HuWNVk2QdDK4Z+sbJGo07eXaVc833sLm6007TWwasTC4s3QKGlh QDuG5dnvf7zs/Z+bYjM5DQc1uwd92ugVUHPsZLhPLlJ9sjM2ApKap8RdJGpqPtDc qTI8z6WjFc+IW0d6GxshXevVDkuid8XyV0fKxmADq+eKhd3DHwneqlYQGQ5g== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-type:date:date:feedback-id :feedback-id:from:from:in-reply-to:in-reply-to:message-id :mime-version:references:reply-to:sender:subject:subject:to:to :x-me-proxy:x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s= fm3; t=1667325482; x=1667411882; bh=A6U+kzuhbpV6DCjZ72Q29RzpIC4m sYQyaXKxULxy43U=; b=iBluY6SWgQPVXkscw3wzEGGWcm8DF+WVvYc/15WWEl98 BMYyLD3tR4OOUeriug/EQZerM5E4Xf3L5Io+Ai04PSuVstCk05bEy69dasGRvfzd Ufv3QygqVQwM1HF/5bAZnfdphKJUuHWBlCrz6gNlppQqU4fy4vf3vuU1eQDwnRLn g121mj4UwFzfJaf9WGNDiBiSkZYmYRcr3jwlleJa8PTMYtgl1qahhT0fyU6g07BC AAVKVgZFbWwUXoQ811zHrbHKLuQmwZTUKbz42oiWCSF49db7/ggIi+f0fZGfkjXV YU4l1Q6S9o3HYIZXkACIpG0w5ebUPC4HqleZj0P/eA== X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedvgedrudehgddutdejucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmne cujfgurhepofgfggfkjghffffhvfevufgtsehttdertderredtnecuhfhrohhmpedftehr nhguuceuvghrghhmrghnnhdfuceorghrnhgusegrrhhnuggsrdguvgeqnecuggftrfgrth htvghrnhepffehueegteeihfegtefhjefgtdeugfegjeelheejueethfefgeeghfektdek teffnecuvehluhhsthgvrhfuihiivgeptdenucfrrghrrghmpehmrghilhhfrhhomheprg hrnhgusegrrhhnuggsrdguvg X-ME-Proxy: Feedback-ID: i56a14606:Fastmail Received: by mailuser.nyi.internal (Postfix, from userid 501) id 1DD5CB60086; Tue, 1 Nov 2022 13:58:02 -0400 (EDT) X-Mailer: MessagingEngine.com Webmail Interface User-Agent: Cyrus-JMAP/3.7.0-alpha0-1087-g968661d8e1-fm-20221021.001-g968661d8 Mime-Version: 1.0 Message-Id: <29d07648-29a9-432a-a666-f9c9e55c32f6@app.fastmail.com> In-Reply-To: References: <20221101170015.GA1314742@roeck-us.net> Date: Tue, 01 Nov 2022 18:57:41 +0100 From: "Arnd Bergmann" To: "Linus Torvalds" , "Guenter Roeck" , "Russell King" , "Masahiro Yamada" Cc: "Linux Kernel Mailing List" , "Miguel Ojeda" Subject: Re: Linux 6.1-rc3 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Nov 1, 2022, at 18:29, Linus Torvalds wrote: > IOW, I expect it is - once again - some random linker-generated stub > that ends up causing problems, where the re-link stage ends up being > unstable because of some subtle alignment issue or other. I think > zero-sized symbols have often been involved. Linker-generated symbols are usually the cause, but those tend to be fixed with the extra pass, and Guenter said that doing an extra pass does not avoid the issue here. I have not tried to understand what the 73bbb94466fd patch actually does, but as the description explains that it uses either 1-byte or 2-byte encodings for some symbols, I suspect this is related to the new problem here, possibly it gets into an oscillating state where making the symbol table shorter causes a symbol to use the longer representation in the next round, which in turn makes the table longer again. What I've done in the past to debug this was to change scripts/link-vmlinux.sh to use a larger number of steps, mainly to see if it eventually converges, grows indefinitely or oscillates. After that I would compare the temporary files from the last two different steps to see which symbols are actually different. Unfortunately, there is no built-in debugging mode in kallsyms, so this is a rather manual process. Arnd