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 B6037C77B7E for ; Thu, 25 May 2023 22:03:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233071AbjEYWDH (ORCPT ); Thu, 25 May 2023 18:03:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57232 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229689AbjEYWDG (ORCPT ); Thu, 25 May 2023 18:03:06 -0400 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:3::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BEB36186; Thu, 25 May 2023 15:03:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=Sender:In-Reply-To: Content-Transfer-Encoding:Content-Type:MIME-Version:References:Message-ID: Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description; bh=Dj12sdoI3n4fpjZdW0Mzq4hB0XZbrqL+DPd7Ji5TGNg=; b=OCLj4wLliabHMtFkwS9TdrlBTx +sUQHLscg7D3U1XckQR1AU8vIZlREBIbja6Flm4wCq352iuput5TrOvIRI7Am1m5KRbQTAH3nwl8H WV4YsWtwhQCEm0g2Dxz7qwfimujPNEESegH7q3eG7jiG72nxyegVOAZ56wYoV9fCZ6hY4lpVZ75O4 l+gIpkKAusosIkiByfIzuBG6VUnilFxNyHUgpmn3TYH+4puMfaHaFuAKS/xK9R2nAE9ywUcqJn58e SDQtg4WdbbSdKs8coQaiRFvXzhTMiA4xctL2MRr5islutX65JKi673zyZeqTVc0ugTorkYue+n/KC vE2uTTKQ==; Received: from mcgrof by bombadil.infradead.org with local (Exim 4.96 #2 (Red Hat Linux)) id 1q2J2Y-000GXY-2w; Thu, 25 May 2023 22:02:34 +0000 Date: Thu, 25 May 2023 15:02:34 -0700 From: Luis Chamberlain To: Linus Torvalds Cc: Lucas De Marchi , Petr Pavlu , gregkh@linuxfoundation.org, rafael@kernel.org, song@kernel.org, lucas.de.marchi@gmail.com, christophe.leroy@csgroup.eu, peterz@infradead.org, rppt@kernel.org, dave@stgolabs.net, willy@infradead.org, vbabka@suse.cz, mhocko@suse.com, dave.hansen@linux.intel.com, colin.i.king@gmail.com, jim.cromie@gmail.com, catalin.marinas@arm.com, jbaron@akamai.com, rick.p.edgecombe@intel.com, yujie.liu@intel.com, david@redhat.com, tglx@linutronix.de, hch@lst.de, patches@lists.linux.dev, linux-modules@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, pmladek@suse.com, prarit@redhat.com, lennart@poettering.net Subject: Re: [PATCH 2/2] module: add support to avoid duplicates early on load Message-ID: References: <20230524213620.3509138-1-mcgrof@kernel.org> <20230524213620.3509138-3-mcgrof@kernel.org> <8fc5b26b-d2f6-0c8f-34a1-af085dbef155@suse.com> <6gwjomw6sxxmlglxfoilelswv4hgygqelomevb4k4wrlrk3gtm@wrakbmwztgeu> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Sender: Luis Chamberlain Precedence: bulk List-ID: On Thu, May 25, 2023 at 02:12:49PM -0700, Linus Torvalds wrote: > On Thu, May 25, 2023 at 11:45 AM Lucas De Marchi > wrote: > > > > Are you willig to merge (a possibly improved version of) your patch > > or the userspace change is still something that would be desired? > > I think a user space change should still be something that people > should look at, particularly as the kernel side patch I'm willing to > accept doesn't catch the "completely serial" cases, only the "trying > to load at the same time that the same module is literally busy being > loaded". > > But I've cleaned up my patch a bit, and while the cleaned-up version > is rather larger as a patch (mainly because of just also re-organizing > the finit_module() code to do all the 'struct file' prep), I'm > actually pretty happy with this attached patch conceptually. > > In this form, it actually "makes sense" to me, rather than being just > clearly a workaround. Also, unlike the previous patch, this doesn't > actually make any changes to the basic kernel_read_file() set of > functions, it's all done by the module loading code itself. > > Luis, would you mind testing this version on your load? It still won't > actually handle the purely serial case, so there *will* be those > spurious double module reads from different CPU's just doing the > things serially, but the exclusive file access region has been > extended to not just cover the actual file content reading, but to > cover the whole "turn it into a a real module" part too. > > Also, this does *not* update some of the comments in the module > loading. I changed finit_module to use "kernel_read_file()" instead of > "kernel_read_file_from_fd()", since it actually now has to look up the > file descriptor anyway. But the comments still talk about that > "from_fd" thing. > > Anyway, this is back to "ENTIRELY UNTESTED" territory, in that I've > compiled this, but haven't booted it. The changes look obvious, but > hey, mistakes happen. > > And the commit message is just a place-holder. Obviously. I won't sign > off on this or write more of a commit message until it has had some > real testing. With 255 vcpus: Before: vagrant@kmod ~ $ sudo systemd-analyze Startup finished in 41.653s (kernel) + 44.305s (userspace) = 1min 25.958s graphical.target reached after 44.178s in userspace. root@kmod ~ # grep "Virtual mem wasted bytes" /sys/kernel/debug/modules/stats Virtual mem wasted bytes 1949006968 So ~1.8 GiB. After: root@kmod ~ # systemd-analyze Startup finished in 35.872s (kernel) + 41.715s (userspace) = 1min 17.588s graphical.target reached after 41.594s in userspace. root@kmod ~ # cat /sys/kernel/debug/modules/stats Mods ever loaded 66 Mods failed on kread 0 Mods failed on decompress 0 Mods failed on becoming 1 Mods failed on load 0 Total module size 11268096 Total mod text size 4149248 Failed kread bytes 0 Failed decompress bytes 0 Failed becoming bytes 474688 Failed kmod bytes 0 Virtual mem wasted bytes 474688 Average mod size 170729 Average mod text size 62868 Avg fail becoming bytes 474688 Duplicate failed modules: Module-name How-many-times Reason cryptd 1 Becoming root@kmod ~ # du -b /lib/modules/6.3.0-next-20230505+/kernel/crypto/cryptd.ko 475409 /lib/modules/6.3.0-next-20230505+/kernel/crypto/cryptd.ko So yeah definitely a pretty good improvement. Sometimes the system boots without any duplicates at all, for some reason Vs the previous attempt. Tested-by: Luis Chamberlain Luis