From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 D930C23507B; Tue, 25 Aug 2026 07:32:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787643125; cv=none; b=W+phSJpoCW0YBdqmPyWDLP8fUDRS1RXb9nDcqbcvXlIShZ0n6LrMWZc9Uh2zT2fsI6qETPMkI0HB+WsfGCN1jtDJhGdt91K4XfD33o4BWi4HTRyyj/GhXosLainoAHhrXSCQj6cV5dLdhWrKHBbYr/iWAkrCvprTZbFWcpdGFbY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787643125; c=relaxed/simple; bh=pOEToaHFZ1KezTVQLT895r8MTCYw9JPZrUoSp64NpPo=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=UcQQ6pH+Ot7ZfhQj1gK8YGneD8EYQz6TRKbXgmifnWglZX7U1L9AY1FWFkUkwpk8u9WyCqQ7TNfNoq4Fkj+nmgV/AxzsDUjnrnLApr+t7INtNf2Ve1QtW+C6BpPL6CIbi0lF1B16x3sXPqsw2T7aVgjZvdeK1mr4WUAfBQg7E3I= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Z4g/5Wuu; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Z4g/5Wuu" 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> 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: <556337a8-5e2b-45fe-a1ba-90a90c1f3c4d@linux.dev> 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