From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-118.freemail.mail.aliyun.com (out30-118.freemail.mail.aliyun.com [115.124.30.118]) (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 C6943342538; Thu, 11 Jun 2026 11:47:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.118 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781178424; cv=none; b=upP/0UmsTWl8yafVyZqeCyKN0smM0JjOCfpMfrZJdg92Z02rHwjxQfL3Fl9X54twzWyQb1DyEZ1SHEO8zzQsm687lZZlx9YPd8+lrJBK8wVVVTsFnwB1yZaJ5oM1TzWf1yLVeWJrkc9jtR5hQrx/1fuKwGYOsuZGMkJNYI0FTuc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781178424; c=relaxed/simple; bh=PHS9TFW+d52ZVhX5Cw2PY2DHNfri0ShsfOBNEuCxOf0=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=ia/pPg3vl3WNR/hoo6y4hjnJ9cxdUo79ziymryR28IvgIj0ecq+8dXm0QToDnWDNghSCbvkCYlOzwWpPv4rho4IEnU5OQz3q3W7OCFrB0lpWfyoYqbO/FMeFdF2C8ne2T9ufJ/9bNyv7EwNb1cwin7j6xkIiYE0LdcUGJ1ROPLg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b=gjDHZN3A; arc=none smtp.client-ip=115.124.30.118 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b="gjDHZN3A" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1781178419; h=Message-ID:Date:MIME-Version:Subject:To:From:Content-Type; bh=SkCGrWKzCfTn3xVMps93ytdggiT1d+I4EJDhk4sAvA4=; b=gjDHZN3AIEZw1wX8W/Si38LLwRytj84y9kN7wKQBDa1mLDOP4FVzZnuMMIRCz5TADXXsgTmu2lwg9ryH9jyxlrDvCNBvIFcsvyii2JJp7XHK6ZZePHFHOoOixyyP9+c3d01TbsocI0CKStmbLt//zTtM1eOmlTXFoTT2wvzjelo= X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R411e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=maildocker-contentspam033045133197;MF=baolin.wang@linux.alibaba.com;NM=1;PH=DS;RN=15;SR=0;TI=SMTPD_---0X4dY2QC_1781178416; Received: from 30.120.38.205(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0X4dY2QC_1781178416 cluster:ay36) by smtp.aliyun-inc.com; Thu, 11 Jun 2026 19:46:57 +0800 Message-ID: <47f472ac-0b07-4ffa-a3d4-04fba621252f@linux.alibaba.com> Date: Thu, 11 Jun 2026 19:46:55 +0800 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: [RFC PATCH v2 00/11] add shmem mTHP collapse support To: Lorenzo Stoakes Cc: akpm@linux-foundation.org, david@kernel.org, hughd@google.com, willy@infradead.org, ziy@nvidia.com, liam@infradead.org, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, lance.yang@linux.dev, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org References: From: Baolin Wang In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Hi Lorenzo, On 6/11/26 2:18 PM, Lorenzo Stoakes wrote: > On Wed, Jun 10, 2026 at 06:29:08PM +0800, Baolin Wang wrote: >> (Note: this patchset is not targeting v7.2, but posted for early feedback.) > > Hi Baolin, > > Speaking broadly, and to repeat what I said to Nico - I'd like to > re-emphasise my _strong_ desire for us to pay down technical debt in THP > code before adding any further major features. > > Really I'd have liked to see us do this _before_ khugepaged mTHP, but I > didn't want to put Nico through more than he already endured with that > series :) > > So I'd really like to see some action on that before we embark on any > further significant changes. > > This is no comment on your changes, just something that we really need to > address in THP generally. > > Will try to give some detailed commentary on the actual changes when I have > time also :) I fully understand the current state of THP maintenance, which is why this is an RFC. I’m not expecting it to be merged into mainline quickly (but thanks to Lance for the comments). Also, as Nico noted, it might be worth reviewing the mTHP collapse selftests in this series firstly? as they can help validate the anonymous mTHP collapse path for future changes.