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]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5EE61C83F1A for ; Thu, 17 Jul 2025 07:25:31 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 010BC6B00B1; Thu, 17 Jul 2025 03:25:31 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id F2B046B00B2; Thu, 17 Jul 2025 03:25:30 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E1A5C6B00B3; Thu, 17 Jul 2025 03:25:30 -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 D0B336B00B1 for ; Thu, 17 Jul 2025 03:25:30 -0400 (EDT) Received: from smtpin24.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 98FDA16061B for ; Thu, 17 Jul 2025 07:25:30 +0000 (UTC) X-FDA: 83672921220.24.32F7B7C Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by imf24.hostedemail.com (Postfix) with ESMTP id 68569180006 for ; Thu, 17 Jul 2025 07:25:28 +0000 (UTC) Authentication-Results: imf24.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=XhkB+VcE; dmarc=pass (policy=quarantine) header.from=redhat.com; spf=pass (imf24.hostedemail.com: domain of npache@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=npache@redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1752737128; 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:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=g2qRJ0vhUxgZfAdGXu3qCJFwuvYHORHNNQHgAFNdhP0=; b=Vp4FK5QTuCKcQVoLnpbZyJxkrl1YHRSr0pwiJnTM6CWwDDMeJi+Zs/hpDs/+X+P9+s2ppX Iiw4fmx137gcJ2A/HZRckYhE7Ta2n+dfqw4cnvKlq79D/ZY1Ym06s4KE0J6Io2kByDdhl2 Y3Ez16EoMWUC5xI/sw2C7tQKl1mHw6I= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1752737128; a=rsa-sha256; cv=none; b=vtxIGjkoBnXndIzzdj3qSAGea7EThbHH7vJ3gTEfrhwzCgvsFuW1LH88WE7yldCXOHF4m0 OiNj5FC6ON4e3GVFNnAm3Q7JJ9ZmbLsiYsoUrxXF6I1ngGmeb4Vp4DNZhNfhAxA76VX6kk 6EhbvPUO2N0RgXq90gCYgxdyfJDX09w= ARC-Authentication-Results: i=1; imf24.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=XhkB+VcE; dmarc=pass (policy=quarantine) header.from=redhat.com; spf=pass (imf24.hostedemail.com: domain of npache@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=npache@redhat.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1752737127; h=from:from: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:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=g2qRJ0vhUxgZfAdGXu3qCJFwuvYHORHNNQHgAFNdhP0=; b=XhkB+VcE3J06GkJh2jDcoqQbCp7d9ODuzDKmY7V1DpdzBGFNvFHovJE5l1qapX1R7MH293 uIvjeUaWMY5wEnjN1bPrmqDXtulTwMqZ14fDUbKqTROU2IFRkdqIDOYWlE5yYrraUjcn71 k1qdhNoMpd0CSBgZc/+G1Z00hO7eJBo= Received: from mail-yw1-f199.google.com (mail-yw1-f199.google.com [209.85.128.199]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-678-f--AQ5GHP_Whpr2vnkUJAA-1; Thu, 17 Jul 2025 03:25:26 -0400 X-MC-Unique: f--AQ5GHP_Whpr2vnkUJAA-1 X-Mimecast-MFC-AGG-ID: f--AQ5GHP_Whpr2vnkUJAA_1752737126 Received: by mail-yw1-f199.google.com with SMTP id 00721157ae682-707cf1b0ecbso10383887b3.2 for ; Thu, 17 Jul 2025 00:25:26 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1752737126; x=1753341926; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=g2qRJ0vhUxgZfAdGXu3qCJFwuvYHORHNNQHgAFNdhP0=; b=lzf61ztBrM6VmthwCQddbVJgpSeSCzYgNeEs9xQ17KCmqPp1y3UTP8/flzrGl0TiBw Beg3E3eXjG3EHZkm39044KUpUqY44+Wt/qSlEXhLH4aQ6Ao0DFFze0ovjEzeAR+WPnw6 et1QT5/lt9acLSc+zy697SOwHIxp++7CD2IRIVmFgf+hKip2sVrMOiUsxTImsUgFBCPg R7iMQy9IG2gF0ksttuZMu81SAchqmUBaOgwxQn58kugT9cnDVa5T1/hYRfrIsSTwcxqk HNqOQ7N+sQygnqdt1OZQKrUZ9Ho4cLoXdGaSG9Bm04uhFA89TTAwEid5EasYZM5D6BH9 J87Q== X-Gm-Message-State: AOJu0YznaeJwY5NJ5VLCeCLB6kr1F05h13q9JqPhvcLMjXUjy/N8Vbw1 qo1N7fLMsAdhwKvDtOhJAyEVyKelF/XFnfbpec7qz7VeclnnR2z4JIQwsdkjWCH5KdnyRW+Dl6n Xk6yZ/zpXxMS8/LVE88UZEWrJcXnmp9mUJdhhgoXCQbnRpHuzvfsdNUsc+8JVYLsMvmTEzkjZjk 1VeD93gi3ijX0ACOhrXIT/CZG3QXs= X-Gm-Gg: ASbGncuyXMYZe4g0zoIMcA/atcC0lDRIMXVWmtKcwvgMEW2PRem+F1rLx/RvvRVZ/+D yPLiKPearE4sLYrUCcgpdGZ6dx8Fi7PlTF8CBvHVMiihsUju3xZWGaI9Ec1xfY5Zlc7E/rF1BfA n2Ncv9W6hOWPrftT5chwUJwWw= X-Received: by 2002:a05:690c:6c8f:b0:70a:2675:70b3 with SMTP id 00721157ae682-71837475aaemr81219357b3.17.1752737125997; Thu, 17 Jul 2025 00:25:25 -0700 (PDT) X-Google-Smtp-Source: AGHT+IE3zLwOVx14CX9ZFk5M7NptbR4Vtkv7y2swdOQcVV2bdsXyIwCQieST6so7r6GPy5LTDbi4OxzkmKDiHQeVo40= X-Received: by 2002:a05:690c:6c8f:b0:70a:2675:70b3 with SMTP id 00721157ae682-71837475aaemr81219087b3.17.1752737125474; Thu, 17 Jul 2025 00:25:25 -0700 (PDT) MIME-Version: 1.0 References: <20250714003207.113275-1-npache@redhat.com> <20250714003207.113275-9-npache@redhat.com> <290d669f-e358-471a-95b7-c46f974742d0@redhat.com> In-Reply-To: <290d669f-e358-471a-95b7-c46f974742d0@redhat.com> From: Nico Pache Date: Thu, 17 Jul 2025 01:24:58 -0600 X-Gm-Features: Ac12FXw-dqZQr1iCc1PpyFCVkqA86TGy_82hTQcSrhEKTcjVPQocXibYjfgQIuE Message-ID: Subject: Re: [PATCH v9 08/14] khugepaged: skip collapsing mTHP to smaller orders To: David Hildenbrand Cc: linux-mm@kvack.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, ziy@nvidia.com, baolin.wang@linux.alibaba.com, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, ryan.roberts@arm.com, dev.jain@arm.com, corbet@lwn.net, rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, akpm@linux-foundation.org, baohua@kernel.org, willy@infradead.org, peterx@redhat.com, wangkefeng.wang@huawei.com, usamaarif642@gmail.com, sunnanyong@huawei.com, vishal.moola@gmail.com, thomas.hellstrom@linux.intel.com, yang@os.amperecomputing.com, kirill.shutemov@linux.intel.com, aarcange@redhat.com, raquini@redhat.com, anshuman.khandual@arm.com, catalin.marinas@arm.com, tiwai@suse.de, will@kernel.org, dave.hansen@linux.intel.com, jack@suse.cz, cl@gentwo.org, jglisse@google.com, surenb@google.com, zokeefe@google.com, hannes@cmpxchg.org, rientjes@google.com, mhocko@suse.com, rdunlap@infradead.org, hughd@google.com X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: 527iLFDtt5uBG022mxr2EY2QJ8ocuGQqLUTuqFkJlgE_1752737126 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Stat-Signature: 4y61rmjqft7ydqyipn8bd5gazdyn83et X-Rspamd-Queue-Id: 68569180006 X-Rspamd-Server: rspam10 X-Rspam-User: X-HE-Tag: 1752737128-406297 X-HE-Meta: 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 xISnB60f YJHZShh/DTfFbmR0VPy2OkPymVH9NT6/DoqZSsNLhtKMVSwBDQbB5993Rsl6JvK8WXIVwhLeHyMIfiLsrV9CHarO6Jc50N+TEe9Hef1Qr12pEDPZk0VQZG3JZ86U8kTTmuFsqGsnIgN5Nt8z3IurVOJVcCW03mwaYVgHt7IoqKBnws2OBr3rZnIriMnVBLMDMym7SKDBMrYAr5NQMqHR1Kpo39b6LyyDQrC4ylnbYbkr5vkUWCdWzGWasf9zlL4GkQ7+icTV5tpbcDk5sEBwJ43N9qTU3W7+4wG2sTPpzvDyBepU6gGqoR6o90suBVqfuEGSGSYizlwa2kQkX59AKcyibzdmFhwWj1Pk0/9M2g/3GuQBlva9yWvknC6RviXeBXJuNB8WG3pF7U+UCz0CBB+WzqTk1IvvEfdq7 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Jul 16, 2025 at 8:32=E2=80=AFAM David Hildenbrand wrote: > > On 14.07.25 02:32, Nico Pache wrote: > > khugepaged may try to collapse a mTHP to a smaller mTHP, resulting in > > some pages being unmapped. Skip these cases until we have a way to chec= k > > if its ok to collapse to a smaller mTHP size (like in the case of a > > partially mapped folio). > > > > This patch is inspired by Dev Jain's work on khugepaged mTHP support [1= ]. > > > > [1] https://lore.kernel.org/lkml/20241216165105.56185-11-dev.jain@arm.c= om/ > > > > Reviewed-by: Baolin Wang > > Co-developed-by: Dev Jain > > Signed-off-by: Dev Jain > > Signed-off-by: Nico Pache > > --- > > mm/khugepaged.c | 7 ++++++- > > 1 file changed, 6 insertions(+), 1 deletion(-) > > > > diff --git a/mm/khugepaged.c b/mm/khugepaged.c > > index 5d7c5be9097e..a701d9f0f158 100644 > > --- a/mm/khugepaged.c > > +++ b/mm/khugepaged.c > > @@ -612,7 +612,12 @@ static int __collapse_huge_page_isolate(struct vm_= area_struct *vma, > > folio =3D page_folio(page); > > VM_BUG_ON_FOLIO(!folio_test_anon(folio), folio); > > > > - /* See hpage_collapse_scan_pmd(). */ > > + if (order !=3D HPAGE_PMD_ORDER && folio_order(folio) >=3D= order) { > > + result =3D SCAN_PTE_MAPPED_HUGEPAGE; > > + goto out; > > + } > > Probably worth adding a TODO in the code like > > /* > * TODO: In some cases of partially-mapped folios, we'd actually > * want to collapse. > */ Done! Good idea with these TODOs! > > Acked-by: David Hildenbrand Thank you :) > > -- > Cheers, > > David / dhildenb >