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]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 89BC1C79F89 for ; Mon, 7 Sep 2026 08:04:29 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 7A2BA6B009B; Mon, 7 Sep 2026 04:04:28 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 754186B009D; Mon, 7 Sep 2026 04:04:28 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 669C96B009E; Mon, 7 Sep 2026 04:04:28 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 49D576B009B for ; Mon, 7 Sep 2026 04:04:28 -0400 (EDT) Received: from smtpin30.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay04.hostedemail.com (Postfix) with ESMTP id E2C9F1A066F for ; Mon, 7 Sep 2026 08:04:27 +0000 (UTC) X-FDA: 85186228974.30.CA06DCE Received: from out30-131.freemail.mail.aliyun.com (out30-131.freemail.mail.aliyun.com [115.124.30.131]) by imf21.hostedemail.com (Postfix) with ESMTP id 2EB5F1C0007 for ; Mon, 7 Sep 2026 08:04:23 +0000 (UTC) Authentication-Results: imf21.hostedemail.com; dkim=pass header.d=linux.alibaba.com header.s=default header.b=tyUIaPE9; spf=pass (imf21.hostedemail.com: domain of baolin.wang@linux.alibaba.com designates 115.124.30.131 as permitted sender) smtp.mailfrom=baolin.wang@linux.alibaba.com; dmarc=pass (policy=none) header.from=linux.alibaba.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1788768265; 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=Q6I4xw0xnOtAHkDCMQZgtHQlZ6+NllaxbRPZMgDJ1jw=; b=vxBl8eEfpVxSZgBdlJWVZ/Ii3URwi6E5uKvdvn5oIX/F2/1z6QZZEoIsBN1i6gGUQntoyt SFW8vLgv3zn1N8FNdhmh80Qe1fkVmDaZihHL09iXvdBz+v36g9DdWwjC0SU/0ylmUNCI1z oUJU2BVSBZkvqC8L6IH9UgPQARa5/gM= ARC-Authentication-Results: i=1; imf21.hostedemail.com; dkim=pass header.d=linux.alibaba.com header.s=default header.b=tyUIaPE9; spf=pass (imf21.hostedemail.com: domain of baolin.wang@linux.alibaba.com designates 115.124.30.131 as permitted sender) smtp.mailfrom=baolin.wang@linux.alibaba.com; dmarc=pass (policy=none) header.from=linux.alibaba.com ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1788768265; b=rCEmM4moXtZ3frY/UBwbr/5JpUU/EubWVH7uBPoxl29dlhsfNnhRfrAwVvmoWsvQi4QHms RXhWhbdQg7IRDQHvPlgsxlM9WY7CDzc68yOYrBL1M7LDc/IYJcRdv7QDTriSG5RhhhD7lO YYSAQW8h1xpIe+30X4vyn+AeedMnUxk= DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1788768261; h=Message-ID:Date:MIME-Version:Subject:To:From:Content-Type; bh=Q6I4xw0xnOtAHkDCMQZgtHQlZ6+NllaxbRPZMgDJ1jw=; b=tyUIaPE99DVxkKK2DolqVABlHAB3VkeXTtEdovWM30UhC2+6cAgbMyVbnkSZYS9jcioblDBpgGcaJXra78xsgw7RWGjLUWS/TGERzDY/YqGVyZaLufsZSiv55aKU6V9nNOu3bM9pQMo+yJ3CzRz1mDmcpR05FwqTmyQGn2VzQ1w= X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R181e4;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=18;SR=0;TI=SMTPD_---0XARLZAw_1788768258; Received: from 30.74.144.134(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0XARLZAw_1788768258 cluster:ay36) by smtp.aliyun-inc.com; Mon, 07 Sep 2026 16:04:19 +0800 Message-ID: <7e0cdf3c-d922-4c53-9a76-75451327d894@linux.alibaba.com> Date: Mon, 7 Sep 2026 16:04:18 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 04/12] mm/collapse: add collapse.h for the collapse interface To: Kiryl Shutsemau , Andrew Morton , David Hildenbrand , Lorenzo Stoakes Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@meta.com, Zi Yan , "Liam R . Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Usama Arif , Vlastimil Babka , Jann Horn , "Kiryl Shutsemau (Meta)" References: From: Baolin Wang In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Stat-Signature: j7kp5rs1inggta547sktjmrgfrjog6p8 X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 2EB5F1C0007 X-Rspam-User: X-HE-Tag: 1788768263-997632 X-HE-Meta: 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 bwjPOGJ5 EqwPzUxEGifhMNqkbtka2U+G6rIBzh4ZaTSc/5DsgMca9RHyAU1o/7IuqTjabXa/L26krXW38lRfIQFlBmW6sIbrCOKSkWUreQdJ80lZag0U6Ov+MbdxCYjpAMDTVD56lhwVePdvMvi8qXeHMRxAlkv/9BA+yjAbDdX9BLoTOQ6Je7+td6CQHARWqtE2xCkC8pfnrOey78lTF4NPSr449RTOs0i61btRC6Ibh/j4Id4KJGNZhN4yH9O1QzzB9a/1A6XZJQm4i1ZKzRtJQNEBTvSj5J0qVajPumTQ/v+Kwy+SS6CN8QZCIAqvbSqHiUwD4S6feV1bOay5CT9o= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 9/4/26 11:10 PM, Kiryl Shutsemau wrote: > From: "Kiryl Shutsemau (Meta)" > > khugepaged.c holds both the users of collapse and the machinery that > performs it. The daemon's scan loop, the sysfs tunables, MADV_COLLAPSE's > entry point and the collapse itself all sit in one file and reach into > each other freely. Nothing marks where a user ends and the engine > begins. > > Start drawing that line. > > Add mm/collapse.h for what the two sides have to agree on: > > - enum scan_result - what the engine hands back; > - struct collapse_control - the state a request carries. > > And two constants move with them: > > - KHUGEPAGED_MAX_PTES_LIMIT -> COLLAPSE_MAX_PTES_LIMIT; > - KHUGEPAGED_MIN_MTHP_ORDER -> COLLAPSE_MIN_MTHP_ORDER. > > Neither is a fact about the daemon, so both lose the KHUGEPAGED_ prefix. > > No functional change. > > Assisted-by: Claude-Code:claude-opus-5 > Signed-off-by: Kiryl Shutsemau (Meta) > --- > MAINTAINERS | 1 + > mm/collapse.h | 67 +++++++++++++++++++++++++++++++++++++++++ > mm/khugepaged.c | 79 ++++++++----------------------------------------- > 3 files changed, 81 insertions(+), 66 deletions(-) > create mode 100644 mm/collapse.h > > diff --git a/MAINTAINERS b/MAINTAINERS > index a9245d827ddb..4d1ff4c76496 100644 > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -17433,6 +17433,7 @@ F: Documentation/admin-guide/mm/transhuge.rst > F: include/linux/huge_mm.h > F: include/linux/khugepaged.h > F: include/trace/events/huge_memory.h > +F: mm/collapse.h > F: mm/huge_memory.c > F: mm/khugepaged.c > F: mm/mm_slot.h > diff --git a/mm/collapse.h b/mm/collapse.h > new file mode 100644 > index 000000000000..1c40229b9554 > --- /dev/null > +++ b/mm/collapse.h > @@ -0,0 +1,67 @@ > +/* SPDX-License-Identifier: GPL-2.0 */ > +#ifndef __MM_COLLAPSE_H > +#define __MM_COLLAPSE_H > + > +#include > +#include > +#include > +#include > + > +/* The most the max_ptes_* tunables accept */ > +#define COLLAPSE_MAX_PTES_LIMIT (HPAGE_PMD_NR - 1) > + > +/* The smallest order a collapse will build */ > +#define COLLAPSE_MIN_MTHP_ORDER 2 These 2 macros are already self-explanatory, and the comments are over-documented. I'd prefer to drop them. With that, Reviewed-by: Baolin Wang