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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 360A3C5DF94 for ; Tue, 25 Aug 2026 07:32:12 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 136786B008A; Tue, 25 Aug 2026 03:32:11 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 0E77A6B008C; Tue, 25 Aug 2026 03:32:11 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id F3FBA6B0092; Tue, 25 Aug 2026 03:32:10 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id D70366B008A for ; Tue, 25 Aug 2026 03:32:10 -0400 (EDT) Received: from smtpin30.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 542EBA36E5 for ; Tue, 25 Aug 2026 07:32:07 +0000 (UTC) X-FDA: 85138973094.30.723CEEF Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf22.hostedemail.com (Postfix) with ESMTP id AFE07C000C for ; Tue, 25 Aug 2026 07:32:05 +0000 (UTC) Authentication-Results: imf22.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b="Z4g/5Wuu"; spf=pass (imf22.hostedemail.com: domain of ljs@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=ljs@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1787643125; b=HHjJJeLj1hxFmOuKFhIWIpU54OP2VCpaj0yAX44l7t1YO3FYOdqsfs/+Vccv5jCre/Ru1Q HU8lMj5F+k99RpEpl/iLrgq9MMAW1YQXqSKbUN3IR42aRVl8aQSVMzeUVUpM1WduIPr8Ku a3oIUg6WTj1nmhiPizi/0FyYPz5aAyk= ARC-Authentication-Results: i=1; imf22.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b="Z4g/5Wuu"; spf=pass (imf22.hostedemail.com: domain of ljs@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=ljs@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1787643125; 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=pOEToaHFZ1KezTVQLT895r8MTCYw9JPZrUoSp64NpPo=; b=gugoDH4j7pIOTUDgOq/2i8ZvziXjV1jfDZqe9x8HiYy/52M3jlfVQlbT662kiQoH3D1DNF OzTLbb48cyPzXw9EEz8aYAzeVOzYpEefBEvzpmGEykIR+b4Nluxs+dqBlGZDkblsG8MIMN Ew/VRkvWe+aZK6Tp1XqFW5fhQCqyfGI= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 8F097410B4; Tue, 25 Aug 2026 07:32:04 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6908D1F000E9; Tue, 25 Aug 2026 07:31:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787643124; bh=pOEToaHFZ1KezTVQLT895r8MTCYw9JPZrUoSp64NpPo=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=Z4g/5WuuSrT94p10shBVAIXPmRKgbAf3s/fvhs/4tFk+uVYx28S171DpFdj0a9Xtu yTgAB0qfoK70a2ye7WIOmkKuqCjxINjcN0eExJDTuRNBqiinabd9CGUcwpYxZmIH3s A0kNWY2SdjirMgff3v1e0bjg5Zda8IR7ORCKEQrBFZoKCrT/hCqjtKapvjkQ2xpfVN aAnIT1hGn9XvE3sPxICXKO90JPq+Dics4zTCwjz0acMygp6SMe5XJ/h3sRF6PIVSHA ijnfHH3HK2dEqvm36yUHge9E/WgJxljCqXRw85kpAtXpDM/79/D+YtvABmbSMjvNJU LC6rJGO/S2iuw== Date: Tue, 25 Aug 2026 08:31:53 +0100 From: "Lorenzo Stoakes (ARM)" To: Atish Patra Cc: Mike Rapoport , Dave Hansen , Andrew Morton , Andy Lutomirski , Borislav Petkov , David CARLIER , David Hildenbrand , Ingo Molnar , Jason Gunthorpe , Jiri Slaby , Juergen Gross , Kevin Tian , Kiryl Shutsemau , "Liam R. Howlett" , Lu Baolu , Nikunj A Dadhania , Pedro Falcato , "H. Peter Anvin" , Peter Zijlstra , Shakeel Butt , Steffen Dirkwinkel , Suren Baghdasaryan , Thomas Gleixner , Toshi Kani , Vishal Moola , Vlastimil Babka , Will Deacon , iommu@lists.linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org, stable@vger.kernel.org, syzbot@syzkaller.appspotmail.com, x86@kernel.org Subject: Re: [PATCH v2 0/5] x86/mm/pat: CPA fixes Message-ID: References: <20260813-cpa-fixes-v2-0-39b4ff90f91d@kernel.org> <556337a8-5e2b-45fe-a1ba-90a90c1f3c4d@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <556337a8-5e2b-45fe-a1ba-90a90c1f3c4d@linux.dev> X-Rspamd-Queue-Id: AFE07C000C X-Rspamd-Server: rspam10 X-Rspam-User: X-Stat-Signature: wuo3knaj19j141jnswemmy41r6qhu1jb X-HE-Tag: 1787643125-133325 X-HE-Meta: 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 QzqNgVBx fO7wYWMTUstUAdm8nClk45yRgyiCTClA/K5zTRMQEtpsVj8onpLcZcrtHHSpzt5KVlvwDAzaFHPXZG0WMdFS60vKxWB5MWU1jCxskmRiV89pfuuMFxUFd/K/I52rgZ85M7+cXsdO/zvL6PU9RoPxwAgD8opiJ1Aq4wPc365LFOxQ+Gje6771P2Gi2ngNdnDaFUySo3TyXER606xCqe0j1ruLftT1xLtAyDEucQjCl9nYtMAIAkB0SjxhSHttOtotSPyRt3n/Z2E8g++EfGIQ63g4O44tQR54ZvHHLf/nvQSqgBIEoTpmr1NU6rMWJ0np0Liw6F3Fz0RA5xauspGfyrTheTFk/2T8zXhR//tLVBpRpyOGzyc5K7qAMqJlFH0BRsXQa Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Aug 25, 2026 at 12:12:32AM -0700, Atish Patra wrote: > Reproduced and verified this series (patches 1-3) on 4vcpu guest running two different kernels > 1. mainline (commit: 77ae27fd98f3) > 2. Ubuntu Resolute 7.0.0-26 (production kernel hitting the issue in a VM) > > The Reproducer consisted of > 1. A debug patch a cmdline-gated stall between the two *pmd reads in vmalloc_to_page() > 2. One taskset-pinned insmod/rmmod worker per module over stock cfg80211/dummy/veth modules > > With the above reproducer, both BUG within seconds in unpatched kernel. > 1. Resolute in 0.71s at alternative.c:2564 (BUG_ON(!pages[0] ...), RAX=0) > 2. mainline at alternative.c:2473 (BUG_ON(memcmp(addr, src, len))). > > With patches 1-3: zero splats across 10 runs each (600s/11,378 module load/unload cycles on mainline and 1200s/55,980 module load/unload cycles on Resolute). Amazing, thanks! > > > Tested-by: Atish Patra I guess should be applied to patches 1-3 only strictly? Or perhaps 3/5? > > > -- > > Sincerely yours, > > Mike. > > -- Cheers, Lorenzo