From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta1.migadu.com (out-75.mta1.migadu.com [95.215.58.75]) (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 E2AE03CA4A8 for ; Tue, 25 Aug 2026 20:06:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.75 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787688364; cv=none; b=QpTUA2LvL0F47Gthgk3ybWOQyYb3L4hjzlYViiZQ6rtpGJeX5GFjtapDgvdeQtY7RgqXf3Px2aoFCcWqCaY2OP+QSN5NANDZS4PSqVlgDn39PKLeYzksR4Rj0C4TqxuOeMcB5dygr7T1OxbAvRYfyPftUgVOCcj5xjlWnidYOFg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787688364; c=relaxed/simple; bh=XbjAz7qal9P/BA1hWjjA2A6ymhlraYwWduqNMnGPNfM=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=jJGiIo3jtFJ10xa2J8pOHoM9tRNVFVuKztLZ+0E4+FyLjNYOWhnHv8wJHMp4l8NU2h7NdyqzPynom5tloWVfIF3zHugl5ftV7BM4Kr6g5KQBDanKi6fOUNp4vsmvNMAOVzp4mZtxLMWC+3CRvCBYt1PeoXHsXevKB7ZbqOCOikM= 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=F9U2jhQT; arc=none smtp.client-ip=95.215.58.75 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="F9U2jhQT" X-Envelope-To: linux-kernel@vger.kernel.org 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=1787688360; v=1; x=1788293160; b=F9U2jhQTev4uP28NPHwP7qg9cVC0YxNRBdvTHtPArQ0MbbPTaCi1UpBz/QCeF39oIA6JP0zR q3SQEbybvl1aBmhYFEkjqvfjnKayhLneiA5C1OiukTjpvXQYs2TOhcIzmpdeENdoY+k20HLtQLt twS2PFIjdz9R5b54EltRitKQ= X-Envelope-To: linux-kernel@vger.kernel.org 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: linux-kernel@vger.kernel.org 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