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 371FB1E9096 for ; Thu, 7 Nov 2024 12:35:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730982936; cv=none; b=eToY7gmb0/1o1Kz1F9Aru76f54x1POfvo0SJYj8GNxK1TeyBYyj+ZzCKOayo6WQozhGCBK8Xn+1qT4MbTzDq3T8Z5Q31PqgPISFnSDUYtGsOehx0+4Nzpx51SYOoOuWg9V1qMElbsRiaImlkyoeS1p9LjJl3vsyIiu0KPjJJviM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730982936; c=relaxed/simple; bh=bHYyx9VSQMMVjl5yxNco7V3t9XCwwSZayOdt/JyZkP4=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=JDNotFQ0uZc+dntSePWidzKq9BalUElIkHn524NRRb697vutDZ3pagzwl49rdGWJavAOVMvaUM72T/HPEBko4wMGjqaMfYNFfDCUB2R5ZuaoMZtY/YC1UC6uEAFgcanI2en72F/C0quxdo07AZo8VCCUOmPjoULL02ybfxosSvo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 21F6EC4CECC; Thu, 7 Nov 2024 12:35:32 +0000 (UTC) Date: Thu, 7 Nov 2024 12:35:26 +0000 From: Catalin Marinas To: Ryan Roberts Cc: Andrew Morton , Anshuman Khandual , Ard Biesheuvel , David Hildenbrand , Greg Marsden , Ivan Ivanov , Kalesh Singh , Marc Zyngier , Mark Rutland , Matthias Brugger , Miroslav Benes , Will Deacon , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [RFC PATCH v1 00/57] Boot-time page size selection for arm64 Message-ID: References: <20241014105514.3206191-1-ryan.roberts@arm.com> <083d9e98-b6b8-4702-a700-24aea95cef9e@arm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <083d9e98-b6b8-4702-a700-24aea95cef9e@arm.com> On Wed, Nov 06, 2024 at 11:37:58AM +0000, Ryan Roberts wrote: > On 31/10/2024 21:07, Catalin Marinas wrote: > > So, first of all, I'd like to understand the overall maintainability > > impact better. I assume you tested mostly defconfig. If you run an > > allmodconfig build with make -k, how many build failures do you get with > > this patchset? Similarly for some distro configs. > > I've roughly done: > > make alldefconfig && > ./scripts/config --enable CONFIG_ARM64_BOOT_TIME_PAGE_SIZE && > make -s -j`nproc` -k &> allmodconfig.log Is it alldefconfig or allmodconfig? The former has a lot less symbols enabled than even defconfig (fairly close to allnoconfig actually): $ make defconfig $ grep -v "^#\|^$" .config | wc -l 4449 $ make alldefconfig $ grep -v "^#\|^$" .config | wc -l 713 $ make allmodconfig $ grep -v "^#\|^$" .config | wc -l 14401 > In the end, I decided to go for r'(\S+\.[ch]):.*(error|note):', which is any > files described as having an error or being the callsite of the thing with the > error. I think this is likely most accurate from eyeballing the log: I think that's good enough to give us a rough idea. > | | C&H files | percentage of | > | directory | w/ error | all C&H files | > |------------|---------------|---------------| > | arch/arm64 | 7 | 1.3% | > | drivers | 127 | 0.4% | > | fs | 25 | 1.1% | > | include | 27 | 0.4% | > | init | 1 | 8.3% | > | kernel | 7 | 1.3% | > | lib | 1 | 0.2% | > | mm | 6 | 3.2% | > | net | 7 | 0.4% | > | security | 2 | 0.8% | > | sound | 21 | 0.8% | > |------------|---------------|---------------| > | TOTAL | 231 | 0.4% | > |------------|---------------|---------------| This doesn't look that bad _if_ you actually built most modules. But if it was alldefconfig, you likely missed the majority of modules. > > Do we have any better way to detect this other than actual compilation > > on arm64? Can we hack something around COMPILE_TEST like redefine > > PAGE_SIZE (for modules only) to a variable so that we have a better > > chance of detecting build failures when modules are only tested on other > > architectures? > > I can certainly look into this. But if the concern is that drivers are not being > compiled against arm64, what is the likelyhood of them being compiled against > COMPILE_TEST? Hopefully some CIs out there catching them. Well, if we are to fix them anyway, we might as well eventually force a non-const PAGE_SIZE generically even if it returns a constant. I'm building allmod now with something like below (and some hacks in arch and core code to use STATIC_PAGE_* as I did not apply your patches). alldefconfig passes with my hacks but, as you can see, the non-const PAGE_SIZE kicks in only if MODULE is defined. So, not an accurate test, just to get a feel of the modules problem. ----------8<--------------------------- diff --git a/arch/arm64/include/asm/page-def.h b/arch/arm64/include/asm/page-def.h index 792e9fe881dc..71a761f86b15 100644 --- a/arch/arm64/include/asm/page-def.h +++ b/arch/arm64/include/asm/page-def.h @@ -12,7 +12,19 @@ /* PAGE_SHIFT determines the page size */ #define PAGE_SHIFT CONFIG_PAGE_SHIFT -#define PAGE_SIZE (_AC(1, UL) << PAGE_SHIFT) +#define STATIC_PAGE_SIZE (_AC(1, UL) << PAGE_SHIFT) +#define STATIC_PAGE_MASK (~(STATIC_PAGE_SIZE-1)) + +#if !defined(MODULE) || defined(__ASSEMBLY__) +#define PAGE_SIZE STATIC_PAGE_SIZE +#else +static inline unsigned long __runtime_page_size(void) +{ + return 1UL << PAGE_SHIFT; +} +#define PAGE_SIZE (__runtime_page_size()) +#endif + #define PAGE_MASK (~(PAGE_SIZE-1)) #endif /* __ASM_PAGE_DEF_H */ ----------8<--------------------------- -- Catalin