From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 20E9F12B9C for ; Tue, 30 May 2023 09:40:35 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C6904C433EF; Tue, 30 May 2023 09:40:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1685439634; bh=rNtDxPIemUYMFmDRq+2vO1N6CRtzqiO5qUW2YSDslnE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=fVWCl+PdPozcwC62Y6L97YzJzDzJtHQQMnW9S2GOh4IlKRTtDE1NzxUxWU59ZEc4W iPECpa8+tqxLd3ZkYeYq4ROellwQksMrelI2RSqOljy2x5OT1wolysjDdffhmBms+X /i0tiBcH5MSwvo6em5tPHOA9/QaOytmnBVwVAL+2TtNpSw5fdUiSOX5r9N+Sco7nBI aK0BQsipGmChcVfwRSE9LZXPOaCUVBCizzVlgw1m9mG4bbZdLjkSVTjhlPTfdrGPg+ BvRQOXd5jiIRC5GcyHmIgY2+CB1EmpfgwUO+GZnoJRtF0PlfGF/yxDmDEOYNaUxwkL Q+YqAQLhAZs4w== Received: from johan by xi.lan with local (Exim 4.94.2) (envelope-from ) id 1q3vqE-0008S2-F8; Tue, 30 May 2023 11:40:35 +0200 Date: Tue, 30 May 2023 11:40:34 +0200 From: Johan Hovold To: Linus Torvalds Cc: Luis Chamberlain , 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: <6gwjomw6sxxmlglxfoilelswv4hgygqelomevb4k4wrlrk3gtm@wrakbmwztgeu> Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Mon, May 29, 2023 at 09:55:15PM -0400, Linus Torvalds wrote: > On Mon, May 29, 2023 at 11:18 AM Johan Hovold wrote: > > > > I took a closer look at some of the modules that failed to load and > > noticed a pattern in that they have dependencies that are needed by more > > than one device. > > Ok, this is a "maybe something like this" RFC series of two patches - > one trivial one to re-organize things a bit so that we can then do the > real one which uses a filter based on the inode pointer to return an > "idempotent return value" for module loads that share the same inode. > > It's entirely untested, and since I'm on the road I'm going to not > really be able to test it. It compiles for me, and the code looks > fairly straightforward, but it's probably buggy. > > It's very loosely based on Luis' attempt, but it > (a) is internal to module loading > (b) uses a reliable cookie > (c) doesn't leave the cookie around randomly for later > (d) has seen absolutely no testing > > Put another way: if somebody wants to play with this, please treat it > as a starting point, not the final thing. You might need to debug > things, and fix silly mistakes. With the missing spinlock initialisation fixed: -static struct spinlock idem_lock; +static DEFINE_SPINLOCK(idem_lock); this passes basic smoke testing and allows the X13s to boot. It does not seem to have any significant impact on boot time, but it avoids some of the unnecessary load attempts as intended: Before: Mods ever loaded 131 Mods failed on kread 0 Mods failed on decompress 0 Mods failed on becoming 24 Mods failed on load 14 Total module size 12587008 Total mod text size 5058560 Failed kread bytes 0 Failed decompress bytes 0 Failed becoming bytes 2437992 Failed kmod bytes 1858992 Virtual mem wasted bytes 4296984 Average mod size 96085 Average mod text size 38615 Avg fail becoming bytes 101583 Average fail load bytes 132786 After: Mods ever loaded 131 Mods failed on kread 0 Mods failed on decompress 0 Mods failed on becoming 4 Mods failed on load 0 Total module size 12587008 Total mod text size 5058560 Failed kread bytes 0 Failed decompress bytes 0 Failed becoming bytes 109776 Failed kmod bytes 0 Virtual mem wasted bytes 109776 Average mod size 96085 Average mod text size 38615 Avg fail becoming bytes 27444 Johan