From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta0.migadu.com (out-166.mta0.migadu.com [91.218.175.166]) (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 1912D38D407 for ; Tue, 25 Aug 2026 20:05:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.166 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787688356; cv=none; b=El6/btc5fib1gTGyxFtY3zRKa7tz2HqJVfopBYpsiKwtMhxfWiibCz/Q+6tz8hOEHn+NgVnP1QBRpqlmtaIT0QD+JImRRb7vabAl4G+jjJCMpVAr0F3neyz59J+fFrsTwgRL2nSXYebW07xmqTQHLQUHNO9vFFtlNlqyck+1eW0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787688356; c=relaxed/simple; bh=XbjAz7qal9P/BA1hWjjA2A6ymhlraYwWduqNMnGPNfM=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=e42aolPq9Bbibk4jabZ7cM4JxY5l1azJVmA+0F5l8kdoEmzngzNpoVbo+6C5OT4A2E641x97gOVlmTbOWF2KlMtGESbP3rNQ001R6LicgDp5eIgkbuIC807Itvpx6BLkqDOaW6KoNbse2yG9TGaPSA9b4h6dCYYa6PEyion3qXc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=QG24ErEg; arc=none smtp.client-ip=91.218.175.166 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="QG24ErEg" X-Envelope-To: iommu@lists.linux.dev DKIM-Signature: a=rsa-sha256; bh=XbjAz7qal9P/BA1hWjjA2A6ymhlraYwWduqNMnGPNfM=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1787688350; v=1; x=1788293150; b=QG24ErEgpybMHabvymrLyO9+hTRr0wTiyYnw0miz0/bwUOjN8piTGcdjwy6cU24XnEU8ogK0 +0TKYeNjDzd3twGpzzXwf2FDNv0M7EmuJguR8duaA2BVHCQmpls23eSDIvC3JjqLCnmnkm9qNQ9 0+At40fQWGczb8kDFBEM+NAQ= X-Envelope-To: iommu@lists.linux.dev Received: from [IPV6:2a03:83e0:1156:1:10b7:9472:4142:b7b7] (2620:10d:c090:500::7:759c) by smtp.migadu.com with ESMTPS id 9b0c0d836eb66a38; Tue, 25 Aug 2026 20:05:50 +0000 X-Mizu-Trace-ID: 9b0c0d836eb66a38 X-Migadu-Flow: FLOW_OUT Message-ID: Date: Tue, 25 Aug 2026 13:05:37 -0700 Precedence: bulk X-Mailing-List: iommu@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 0/5] x86/mm/pat: CPA fixes To: "Lorenzo Stoakes (ARM)" 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 References: <20260813-cpa-fixes-v2-0-39b4ff90f91d@kernel.org> <556337a8-5e2b-45fe-a1ba-90a90c1f3c4d@linux.dev> Content-Language: en-US From: Atish Patra In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 8/25/26 12:31 AM, Lorenzo Stoakes (ARM) wrote: > 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? Yes. 1-3 sounds good. >>> -- >>> Sincerely yours, >>> Mike. >>> > -- > Cheers, Lorenzo