From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.subspace.kernel.org (Postfix) with ESMTP id A0DBF606A32E for ; Thu, 5 Nov 2026 16:20:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=kqGX0Qru Received: by kanga.kvack.org (Postfix) id 982646B05B0; Thu, 5 Nov 2026 11:20:09 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 90C7A6B05B1; Thu, 5 Nov 2026 11:20:09 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 7D3446B05B2; Thu, 5 Nov 2026 11:20:09 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 45A506B05B0 for ; Thu, 5 Nov 2026 11:20:09 -0500 (EST) Received: from smtpin27.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay03.hostedemail.com (Postfix) with ESMTP id AE22DA0AA9 for ; Thu, 5 Nov 2026 16:20:08 +0000 (UTC) X-FDA: 85401577296.27.6CE43DE Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf19.hostedemail.com (Postfix) with ESMTP id B50E91A0006 for ; Thu, 5 Nov 2026 16:20:06 +0000 (UTC) Authentication-Results: imf19.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=kqGX0Qru; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf19.hostedemail.com: domain of maz@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=maz@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1793895606; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=rAfgYJb3CU0ZmVV1RZG4jgQB2Ko2DnWepqbK4ErMKrU=; b=H3TtiBro24kysLDYaKxmGQLiT0F7mR7uktn3mx3uxIUCURrkp6QfPbrjQKRBFDuUamwc4g MO5ViIsOhszgPFJ2lMOOi5qWI+B9SWar0s3sm56hcFyg+J3Za6jt2v5ErV8zjVslKW+3Z1 8OiHFx2U5C8x+1HJNM34LxwiNTi/Feo= ARC-Authentication-Results: i=1; imf19.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=kqGX0Qru; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf19.hostedemail.com: domain of maz@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=maz@kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1793895606; b=0jdgAYOZo5liyjjJBmKlQv9UjtTUlCHENxYKFVIsA9Fmr6U1knmUJDxYfkozthADTjvpgm QW/UEFQ9TS5YOBbvj0S6sme6DqNymcpFA3Ag4DteOg0wv/7p2yY1nnIEPUQxLVDdEsdZTu w3g7tMkKpDmVvbNuPcERzpapxoZw8QA= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id E449343C67; Thu, 5 Nov 2026 16:20:05 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B740A1F0093A; Thu, 5 Nov 2026 16:20:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793895605; bh=rAfgYJb3CU0ZmVV1RZG4jgQB2Ko2DnWepqbK4ErMKrU=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=kqGX0Qru58U+OHeadfWAMb6N1IIP8ucW5R79h/yfRES/lFapRAfnom+jxQL2+D3KV 3VQbn8o338D9ZOjUnPRfSX9vx3or6dxyvJDRfb8uWtUPdtBR1YkqA8RDo+wLHUnYhD SNKeQKf9n/HutLT2t0XYRKog0ysFPvZ1lye/wN0HCNBMvjQH3Fs6cJxkrYv8hOlO2P fawYH0KgT3QqQvH5C6FRD45wGODhb3YMbpl9C6RamZcNoZb9DyM32ieGHf6D7TfVFm AcKZwanrXLScxtreb6moYqjqIjr8iAVyG8uq0LOftKSGgBAYij0D4VGSlvcplT2XAz 3CU89qOPiF6Ow== Received: from sofa.misterjones.org ([185.219.108.64] helo=goblin-girl.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.98.2) (envelope-from ) id 1xP0C3-0000000BiuJ-000O; Thu, 05 Nov 2026 16:20:03 +0000 Date: Thu, 05 Nov 2026 16:20:01 +0000 Message-ID: <86zevn1c9a.wl-maz@kernel.org> From: Marc Zyngier To: "Aneesh Kumar K.V (Arm)" Cc: linux-coco@lists.linux.dev, Andrew Morton , Baoquan He , Mike Rapoport , Pasha Tatashin , Pratyush Yadav , Catalin Marinas , Christian =?UTF-8?B?S8O2bmln?= , Jason Gunthorpe , Joerg Roedel , Marek Szyprowski , Robin Murphy , Steven Price , Sumit Semwal , Suzuki K Poulose , Thomas Gleixner , Will Deacon , Russell King , Benjamin Gaignard , Brian Starkey , John Stultz , Mark Rutland , Radu Rendec , "T.J. Mercier" , Madhavan Srinivasan , Michael Ellerman , Nicholas Piggin , Christophe Leroy , Ritesh Harjani , Shrikanth Hegde , Alexander Gordeev , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , Christian Borntraeger , Sven Schnelle , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H . Peter Anvin" , Kiryl Shutsemau , Rick Edgecombe , "K . Y . Srinivasan" , Haiyang Zhang , Wei Liu , Dexuan Cui , Long Li , Paolo Bonzini , Vitaly Kuznetsov , Andy Lutomirski , Peter Zijlstra , dri-devel@lists.freedesktop.org, iommu@lists.linux.dev, linaro-mm-sig@lists.linaro.org, linux-arm-kernel@lists.infradead.org, linux-media@vger.kernel.org, linux-mm@kvack.org, kvmarm@lists.linux.dev, patches@lists.linux.dev Subject: Re: [PATCH v9 14/14] irqchip/gic-v3-its: Preallocate VPE L1 tables In-Reply-To: <20261104164555.3555725-15-aneesh.kumar@kernel.org> References: <20261104164555.3555725-1-aneesh.kumar@kernel.org> <20261104164555.3555725-15-aneesh.kumar@kernel.org> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/30.1 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO) X-Archived-By: MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: aneesh.kumar@kernel.org, linux-coco@lists.linux.dev, akpm@linux-foundation.org, baoquan.he@linux.dev, rppt@kernel.org, pasha.tatashin@soleen.com, pratyush@kernel.org, catalin.marinas@arm.com, christian.koenig@amd.com, jgg@ziepe.ca, joro@8bytes.org, m.szyprowski@samsung.com, robin.murphy@arm.com, steven.price@arm.com, sumit.semwal@linaro.org, suzuki.poulose@arm.com, tglx@kernel.org, will@kernel.org, linux@armlinux.org.uk, benjamin.gaignard@collabora.com, Brian.Starkey@arm.com, jstultz@google.com, mark.rutland@arm.com, radu@rendec.net, tjmercier@google.com, maddy@linux.ibm.com, mpe@ellerman.id.au, npiggin@gmail.com, chleroy@kernel.org, ritesh.list@gmail.com, sshegde@linux.ibm.com, agordeev@linux.ibm.com, gerald.schaefer@linux.ibm.com, hca@linux.ibm.com, gor@linux.ibm.com, borntraeger@linux.ibm.com, svens@linux.ibm.com, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, kas@kernel.org, rick.p.edgecombe@intel.com, kys@mi crosoft. com, haiyangz@microsoft.com, wei.liu@kernel.org, decui@microsoft.com, longli@microsoft.com, pbonzini@redhat.com, vkuznets@redhat.com, luto@kernel.org, peterz@infradead.org, dri-devel@lists.freedesktop.org, iommu@lists.linux.dev, linaro-mm-sig@lists.linaro.org, linux-arm-kernel@lists.infradead.org, linux-media@vger.kernel.org, linux-mm@kvack.org, kvmarm@lists.linux.dev, patches@lists.linux.dev X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: B50E91A0006 X-Spam-Status: No, score=-5.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS autolearn=no autolearn_force=no version=4.0.1 X-Stat-Signature: cgbnqc58mswnm6u8sqg63ksxfstybpz8 X-HE-Tag: 1793895606-104165 X-HE-Meta: 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 m6ecw7gy +91HpvKO/rVdblCHwdKyCYNYdInFKoFyjHjDqq0s7UtYE68oMHCq/FfUYj2D4IfxPJ0cqSniqeuFuSvT3DJK+YdrfsvInfQoC4+/sssxfZjiCbV/HwyR/phMsC7zdauvUvtSIL7Kdw9iDl8IKtq5QpkSpZjMKjORozflipKDnON+dGBD/QRNOaUuGGyleaEw7gjrZNUFK8jSmym28J+iqPSMxTMsScw+jr1ECGsiMD7bB1mMY/8P9u2o4jPvO+gM8VnL7kbOtAjixLI8EsilGxNOuvsHYmfWrs+uhB6UCadIRjwp9ZSiTd++2Q3sNCFvlbXg0 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Wed, 04 Nov 2026 16:45:55 +0000, "Aneesh Kumar K.V (Arm)" wrote: > > VPE L1 tables are allocated from the CPU-starting callback, where sleeping is > not allowed. Remove the page allocation from this atomic path. > > Use a blocking allocation for the boot CPU and record the resulting table > order. Allocate a page of that order from the sleepable CPU hotplug prepare > stage for each secondary CPU. Consume the preallocated page only when the CPU > cannot inherit an existing redistributor or ITS table. > > Reclaim unused preallocations after the CPU reaches the online state, and from > the prepare-state teardown when CPU bring-up aborts. No. The way to do it is to move the ITS probing out of the non-sleepable CPU hotplug path. I proposed a potential hack at [1] (which I find far more palatable than this proposal), but the real fix is to probe the ITSs as devices. Putting even more ugly hacks on top of the existing PoS driver is definitely not an acceptable outcome. M. [1] https://lore.kernel.org/all/86tswrkrh4.wl-maz@kernel.org/ -- Without deviation from the norm, progress is not possible.