From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wr1-f47.google.com (mail-wr1-f47.google.com [209.85.221.47]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7EB04173 for ; Sat, 8 Jan 2022 15:16:09 +0000 (UTC) Received: by mail-wr1-f47.google.com with SMTP id o3so17141556wrh.10 for ; Sat, 08 Jan 2022 07:16:09 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=uucTvtg1YQMjIP0qoj4ZoGgmtYYbV+cou28W1zzliws=; b=A1k4VDrvuCebTVmunqofPKMOGmzg8ckI4u3okugvYNraxLKTbhFLXWZtX7al2ZBWel C2IDdncztk9+bTxGS2CMcIEC90FjXYHJsK57rvHjnmtL7dZ4ni+XGGQZqRKMDVbXwA+I A/qubHWE6yhjNFLpJ1nYxOZQN6lv9ZSARxmH6lAQmEFGA//nsrVdt/ZBjTWCbbpcIyiF AiINtrv/KEXVOYUvxi0YePELa1aR+mjbX+MyRUeN2iWv5v7zHY00adHqWoMZ1w6AIwYG yAdo/e6WAPwgaCMemGqmu4n6agyA3tzb2nfcWhD/PWFk808VK5QR8afc0hN0nFBbsGrl B0Uw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to; bh=uucTvtg1YQMjIP0qoj4ZoGgmtYYbV+cou28W1zzliws=; b=dQvkAaNqAuKqxvWnyB/YIBHK9ycbHFZleaLjgUJ2HryXf2GflspI3t4GGI1XEGT/MN Y4xClmcB2XLlvUrhL6Drnos8/afby0X0rVVcBv10f+FDEl/TTkW9kAkYwfSCljBj7mIf TyWjtSz+sC2ivgrQnzmSNIThoFlR6cLtOlxZGftAnx02vj8CNlMt36h6BgM5MOuEa0fn FnXDqUDIYRoFzgC+qfN39zTT+txBTjQRJMfKNPso4jVg7ZEl0CKGCpaGgXYOAXWM8LfX F96AXHWJVkEwednacbDi7GuwBkOyv73GEuVCLlEYQ8CjAOl1oei6HKFjPcRAz5HoKH20 xwSQ== X-Gm-Message-State: AOAM530FBq79bm6p/wkhCRXIY2KI+t66PZZUefortzPvrVOwybw4eMZb YnEJAedSKEeWMQSqi2JSmF4= X-Google-Smtp-Source: ABdhPJwLiHYa3upjIY0klY4+zWxYl5EZgcOkEErx4i8nnXRKMGzyDpAok+0VJvZ5yqbi98eRiZYTTQ== X-Received: by 2002:a5d:6d0a:: with SMTP id e10mr58254890wrq.65.1641654967930; Sat, 08 Jan 2022 07:16:07 -0800 (PST) Received: from gmail.com (84-236-113-171.pool.digikabel.hu. [84.236.113.171]) by smtp.gmail.com with ESMTPSA id o29sm3109607wms.3.2022.01.08.07.16.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 08 Jan 2022 07:16:07 -0800 (PST) Sender: Ingo Molnar Date: Sat, 8 Jan 2022 16:16:05 +0100 From: Ingo Molnar To: Nathan Chancellor Cc: Linus Torvalds , linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, Andrew Morton , Peter Zijlstra , Thomas Gleixner , Greg Kroah-Hartman , "David S. Miller" , Ard Biesheuvel , Josh Poimboeuf , Jonathan Corbet , Al Viro , llvm@lists.linux.dev Subject: Re: [PATCH 0000/2297] [ANNOUNCE, RFC] "Fast Kernel Headers" Tree -v1: Eliminate the Linux kernel's "Dependency Hell" Message-ID: References: Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: * Nathan Chancellor wrote: > I tried to checkout at 9006a48618cc0cacd3f59ff053e6509a9af5cc18 to see if > I could reproduce that breakage there but the build errors out at that > change (I do see notes of bisection breakage in some of the commits) so I > assume that is expected. Yeah, so the underlying problem is that these two commits want to be a single commit: # Commit #117 headers/deps: Move task->thread_info to per_task() # Commit #106 headers/deps: Move thread_info APIs to As we can only switch ARM64's to use per_task() - which requires - if we first fix & simplify 's header dependencies, which is done to a sufficient level by: # Commit #556 headers/deps: Optimize dependencies, remove inclusion So it's a catch-22, and quite a complication, and a bisection breakage distance of ~450 commits, with a lot of ordering assumptions & conflicts along the way, should we attempt to move the first two to later stages. :-/ But today I've restructured the tree, and the -v2-to-be tree is now fully bisectable on ARM64 too. :-) There's a single, late per_cpu() conversion commit, after the first phase of simplifications: headers/deps: Move task->thread_info to per_task() I'd guess that either this one is that breaks SCS for you, or the ::thread conversion: headers/deps: per_task, arm64, x86: Convert task_struct::thread to a per_task() field I've pushed out these fixes to the sched/headers branch a couple of minutes ago, and this will be part of the -v2 release as well. Thanks, Ingo