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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 4FB5CCCD1BF for ; Tue, 28 Oct 2025 12:59:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Type:MIME-Version: Message-ID:Date:References:In-Reply-To:Subject:Cc:To:From:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=qv3GohWqQgrGHwaxj2d2Xaf/EkkHHeIVB+/xSV7yFv4=; b=d/grMArRg6XdUyCmq0xmJyCAjH JsMg2tdQV2cHGhn8lmc2g1UGMMDTGAhxTz4wvTeKeASLm6jYfQLlyHz0Zo3mA7/NRlnZUZE30ZQcZ /IHJtaYrZUNxSCAaqLjBolesUQ/ANod9HddA5PpubQnBiEXvyeKn1Eq+6GrM62kVlzw+iKTy9YbMi JrLP5rHuBmErejO4/iTUSzZSxKY+g6y66v5z2Yu9qq7+mKV7uc+qFTuJYmPiRidwsJsQ5yCVGG51a 6uTclVsK/nnT7oKDTg7ojMwEduf0QHeCr0Sn20IV34TIrMwxmDQsXzG/KiP8AgLRaT/eJe7rQdQ2/ Loq/X1qw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vDjII-0000000FyeR-2V3H; Tue, 28 Oct 2025 12:59:22 +0000 Received: from galois.linutronix.de ([2a0a:51c0:0:12e:550::1]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1vDjIG-0000000Fydx-1fRD for kexec@lists.infradead.org; Tue, 28 Oct 2025 12:59:21 +0000 From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1761656352; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=qv3GohWqQgrGHwaxj2d2Xaf/EkkHHeIVB+/xSV7yFv4=; b=NE7okjrhYT+Phe6z31Nw+rc4ReQOJbVOhEpDE0z7KFgiM3Q/3cN/zek9aIeCo9gGbJyX1y M671Iw2qv7qi0MON7KLZwUOZ4cdId0WZ4M+ZFIzoLHPMGkqKg1TCfV5Q73lhXEZ+bFI05v ZG6b+y7VoJfXX8OIuowC6DaTFd2R64VkaaTYrzEWfyfVDHKIytM0z+oUWbawWDu5GkVfj8 +XaFEcHKI0p/bAHWnBVxH6dRoDRvZA3uFm0qZktS9YQl3Vdwmd/5rZOYXSB7c9BDQ4Rg0u 7XJz0ljMHA71Uz+Zxv6/yctqaAjEuQJtKO2xcvKv50oJZJtbBMbClt8samzpCQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1761656352; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=qv3GohWqQgrGHwaxj2d2Xaf/EkkHHeIVB+/xSV7yFv4=; b=O66dcqLcRsfw63bXuc/kWIr3HD97R+qJW70ShL4pAweT0heNzZ124tHYRZqer8Z4SUGdP/ WElduijmtsTraaAQ== To: Pingfan Liu Cc: kexec@lists.infradead.org, linux-kernel@vger.kernel.org, Waiman Long , Peter Zijlstra , Juri Lelli , Pierre Gondois , Andrew Morton , Baoquan He , Ingo Molnar , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Valentin Schneider , "Rafael J. Wysocki" , Joel Granados Subject: Re: [RFC 2/3] kernel/cpu: Mark nonboot cpus as inactive when shutting down nonboot cpus In-Reply-To: References: <20251022121345.23496-1-piliu@redhat.com> <20251022121345.23496-3-piliu@redhat.com> <877bwgw9yf.ffs@tglx> Date: Tue, 28 Oct 2025 13:59:11 +0100 Message-ID: <87qzunuqqo.ffs@tglx> MIME-Version: 1.0 Content-Type: text/plain X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20251028_055920_575944_4167DC5C X-CRM114-Status: GOOD ( 11.59 ) X-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "kexec" Errors-To: kexec-bounces+kexec=archiver.kernel.org@lists.infradead.org On Tue, Oct 28 2025 at 10:51, Pingfan Liu wrote: > On Mon, Oct 27, 2025 at 06:06:32PM +0100, Thomas Gleixner wrote: >> When kexec() is in progress, then running user space tasks at all is a >> completely pointless exercise. >> >> So the obvious solution to the problem is to freeze all user space tasks > > I agree, but what about a less intrusive approach? Simply stopping the > DL tasks should suffice, as everything works correctly without them. What's intrusive about that? Task freezing exists already. > I have a draft patch ready. Let's discuss it and go from there. > >> when kexec() is invoked. No horrible hacks in the deadline scheduler and >> elsewhere required to make that work. No? > > To clarify, skipping the dl_bw_deactivate() validation is necessary > because it prevents CPU hot-removal. If you freeze stuff there is nothing to do. Hibernation works exactly that way without any magic hacks in a particular scheduling class, no? Thanks, tglx