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 657C1C3ABC0 for ; Thu, 8 May 2025 18:05:23 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id B83E16B00A5; Thu, 8 May 2025 14:05:21 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B31FD6B00A6; Thu, 8 May 2025 14:05:21 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 9FA076B00A7; Thu, 8 May 2025 14:05:21 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 80CF46B00A5 for ; Thu, 8 May 2025 14:05:21 -0400 (EDT) Received: from smtpin17.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 5BF231A0D94 for ; Thu, 8 May 2025 18:05:22 +0000 (UTC) X-FDA: 83420517684.17.F1397C2 Received: from mail-ej1-f46.google.com (mail-ej1-f46.google.com [209.85.218.46]) by imf04.hostedemail.com (Postfix) with ESMTP id 175C940013 for ; Thu, 8 May 2025 18:05:19 +0000 (UTC) Authentication-Results: imf04.hostedemail.com; dkim=pass header.d=gmail.com header.s=20230601 header.b=m5cTzvH8; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf04.hostedemail.com: domain of usamaarif642@gmail.com designates 209.85.218.46 as permitted sender) smtp.mailfrom=usamaarif642@gmail.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1746727520; a=rsa-sha256; cv=none; b=yPHKz385b8U1Um1/jx48X1TY4EVPqYMdl0TJiVlvmHlv1Ti50lEt94CUmS9W5ULZmqPBC/ 04J/FwuJL5IDdA1lz8ubC/qoTNI5dD5zcfcYmvo8N2GXWcfFujdcy//mnPogGC+xUY50Vv Ma77Ei4nGRIG89LYtUmNx/Vg8X5bow4= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1746727520; 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=e7hbLN/6f2Sh/M0mcYIBWUh9AjjCpvmSzUgBLIeIAR0=; b=XCswdJ1+GHwjAbO9IdK5GcxgyparjhlvQsFW8u00hZfBFPl2FkVA5HztNohTrxe8FThsPb H2OLTRYy4ofCG9hVKprAplCaHkaGB/sYBwrrJ5o76F5HCzXMgEOsM8lK8xctkGYg/PbSYy P8guH5ME4wwpT6dsFx5eAr5V6eqV0KQ= ARC-Authentication-Results: i=1; imf04.hostedemail.com; dkim=pass header.d=gmail.com header.s=20230601 header.b=m5cTzvH8; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf04.hostedemail.com: domain of usamaarif642@gmail.com designates 209.85.218.46 as permitted sender) smtp.mailfrom=usamaarif642@gmail.com Received: by mail-ej1-f46.google.com with SMTP id a640c23a62f3a-acb2faa9f55so159277266b.3 for ; Thu, 08 May 2025 11:05:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1746727518; x=1747332318; darn=kvack.org; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=e7hbLN/6f2Sh/M0mcYIBWUh9AjjCpvmSzUgBLIeIAR0=; b=m5cTzvH8yJta0Rdo6ND7ERAlzaUidosjtp9MPF9CwGFz9XctaJpELO16Uctk+Umm+B YKhZw8F8k4JAIcPubG62bA5nUeAryF2fo3zJdv7G8usKNlVTidlVZXmcuZa/zKx0r2HE 6rn/QaH2h5+7X4YsJZ6fYweoE/EtNVRjjd7la3iscPWvdJ86ke4V3pwOwud1wgJzLq/y DnKFMZJR6al0+kixIzgxsiTdZINwrT63WryfyN1eLlNplsmygIi9Ckk6Os77oEjPQxvY CukInt6HcgwxzAVnLQNctJ+71Mnq98IoqsE1WeAX87hgSZXWc36fG024XZZUYeHwtQ9m l+wA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1746727518; x=1747332318; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=e7hbLN/6f2Sh/M0mcYIBWUh9AjjCpvmSzUgBLIeIAR0=; b=Bh+gVNZcIDApRVWAwSyL+KRYy4AJZBFbwjrKjSf/QW0JLPhIV3x1ApTCXcmpdoZ86l +7AggaeiLD5jUUJ4Gqxs2S/ZYuNjz1n8l9w/5NlEa/GDYSo8L1t+Ugdq/xcqxtpz3WZ8 j28X3vJb2u8lceWbENsmEnYDPu31ZfbtCnMleclNZrkPqKA4IEC2dnE858maTMZ+d4JJ RWImnQ6J6i/BRU/PTh4mshxUdV+9dApsk+dX6HwTmLpuFst20wUKG4gos8BRh+gAo/fH +UwS7jAwtCpU+y/iLwylDBEKd5leofF3Z6h8O2yYS7cNerl34FaSwBvUktxpdacQnsKl TR5w== X-Forwarded-Encrypted: i=1; AJvYcCUen04paQMWlafHzgvOjzrUSi8AeM1a63Zs3fghWQZW2WP1M780QkHk3ymIet446gT8sreiH6FXrg==@kvack.org X-Gm-Message-State: AOJu0YyWtVJQxrpQCsrYrdVo4EjFXUeW2JEMKRfsNGRain9/sQ4YiRg0 57haQvCOxBwmyN4gE3tlEyLS/tjN9n6RS7twcEoWkZeArdAm0BpM X-Gm-Gg: ASbGncvWfHK69uvOsvlEynz5OBYTWle5XcmHmOBMd+AmDx8cttJoaWnyJstjfpQHNtf e3nClRG5LbPWhmKGooVd8TN7HRIaRFDeGPLABkyoy4eJEwk4RK/aeeyyFhM8xdRbx8pbtQ1bNVu y2Vkl8NSIWm0yrQTiO9/PU6grlPdXpU2eWPJ+InrrI3eaQ8OGStDXsGXCkNQVBMXLEAOm6F6mWb ROAKhRhztmh9BhOdRVOUVXUA/Je23tNikEGDtxTsNwZy6vx5N/n5QT5u8hbanXa2OVPaqBPODC7 4i0I1100O80OxER5gKXoyrEVskcuPgyL4y5XPuB6kQXOKApc8hDAOWl07QSn+xnrgGg7EakIp1X +qYaYayNxdQcCIwK5E4vARbUVeQ== X-Google-Smtp-Source: AGHT+IFSbSzd1mKaH5gakwmdcCdpcWo+Wwbka7XYFXUOkAB0Q9AqaWPX9ZxwaQwOnuQs7wVgTXG0Og== X-Received: by 2002:a17:907:3cd4:b0:ac4:169:3664 with SMTP id a640c23a62f3a-ad218fa9075mr63541266b.33.1746727518000; Thu, 08 May 2025 11:05:18 -0700 (PDT) Received: from ?IPV6:2a03:83e0:1126:4:1c6a:8675:ac47:a9d0? ([2620:10d:c092:500::4:d248]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-ad21988d43asm19420566b.178.2025.05.08.11.05.17 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 08 May 2025 11:05:17 -0700 (PDT) Message-ID: Date: Thu, 8 May 2025 19:05:17 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 0/1] prctl: allow overriding system THP policy to always To: David Hildenbrand , Andrew Morton , linux-mm@kvack.org Cc: hannes@cmpxchg.org, shakeel.butt@linux.dev, riel@surriel.com, ziy@nvidia.com, baolin.wang@linux.alibaba.com, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, npache@redhat.com, ryan.roberts@arm.com, linux-kernel@vger.kernel.org, kernel-team@meta.com References: <20250507141132.2773275-1-usamaarif642@gmail.com> <3b5d929f-ec2f-4444-825f-81e71f804033@redhat.com> <3f7ba97d-04d5-4ea4-9f08-6ec3584e0d4c@redhat.com> Content-Language: en-US From: Usama Arif In-Reply-To: <3f7ba97d-04d5-4ea4-9f08-6ec3584e0d4c@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 175C940013 X-Stat-Signature: 79wjf84pqwrd5h5as4kxsb9x6qdttour X-Rspam-User: X-HE-Tag: 1746727519-617643 X-HE-Meta: U2FsdGVkX18DWHBkZRNC32ImzF39x4niBDmSl6Ho1K7+ks6w5gNg1bVdNOsU01Na6GHJ/t4MYNP71sxXDqePa0QQ1Mh9O9IoOIV2/kfCQCT4u3Fpj/pLd2xi3GMaEyHULOR99y02JHNXxV8w3yvm/cM1UJrMGpSvK0bE2MPK9V4V0JyYW620H8hJk7G+YS/O0eYdIPn9wDx0ntep9oAqGQItDEXvoIIIa75NYZ3281HQaDcFPM4tJ1bMCx5UvWZY+LoLQ8Mv6cCMCiG8/fzBtSryUngEhAci7Gmt3Jc2v5xwRCoFdGP8QLEZlZj26nQOkGkC67xb/uU23XoOLA9+f9GKp+Y/bYuIuLViglJzbg9v1vxFuidrJbQfHfDGlRshSCNjx5Xum2nA2zKxye2f8a4OHgEY9Miq37z099DMRD6HqQ56GF4golpaifjyDvTUTEbpHzZrnfwj0/PYcktjZatj65O+i/38WSf3ZYZaL/k8/Me3Ztx16AZxKQBPmnpIe8q9k8liNM/DTsvyzoJ+VWu+XYpHTr5zmHwCJqPffDTSm/qDJ+QCLKmkz0Kd0CykGv5qLF1orsOjqqnuADDAC2CW60mcPltLN1RRBI8GsYlLMqs2qRV+wYaV94bnIK828Ato5/nVbN7LCxik+jiu++U44tJiCHuhmmuz0wZHzs6cfwWTaW0ooBJtCgvAjlFpoP5K+qrlDDynd3UgoOt+eZNcE0rGfjk2kIaU/qP7DQUvwH5L4tRGZaWa2Nf5t7ZmkWYTdYpsTfGMtu9EGNOViTKOFU71Jnr3/EayO+0MtBRPVNA/aM0S1t9gP3Ng+sDqNgRwi99EhBEm/bpzU7PVqPlDECO7GJldtVln4mSwriOm4M43smnAZ2AD6h3AeVik2bPPRiUT+/ffLNNj8bs/6G1Xt80Zhdc6OqtkS9kjjzSeH7Hwc2SmZqH1723x5ejNchd4OxFI6tEBxc/tEgN ZJh3iAPF U7uOWx1hDFd5Q5r4u/pLIwaS+jpQ6YsCpWBxWYGLuB4mcTxv7/RdxLfyA1rDkVaUXwsq1YdO2KxihYwl8hy6guZXOTnJ6jgomVSJGtq9iPqYeC8XM8rlKcs0NSHOqAe4pGXnCDhHdmwNB4Am2Y4B773pRbvJgz7/3vjDlOYro+CiWNDd0sD1k0L/aleByUIjf68ZZIUZ30hGueLxA4a4EN9dGs5N5xPRbfqCaRKpijNdzlDASCN5DxEGSXhG5OIVfDniCyfzVKyg9uIHg98nG1GBamUu8r8B92o2ZT+0lTwsgReErrXOxDbEsPqsqUCvwIRYMgauirBTmRnWF8WagJ7I50bSQ8kMGHNADeWzKMbpfLxmpqe5OGk5GnuczjcTM7RNWgmPibqnE17FllYRWyIqT3qVhUOG0eoInlmsMOTmZ7HcmCgbGhWqFJ/Vquwqt6qYGjmxJitO4YGTLX4tJXpSPdg== 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 08/05/2025 18:39, David Hildenbrand wrote: >>> We did something similar with PR_SET_MEMORY_MERGE. >>> >> >> For this you mean the prctl command would do for_each_vma and set VM_HUGEPAGE to implement point 2. > > Yes. The expectation would be that the prctl is either a) triggered early when there are not that many VMAs yet or b) inherited during fork+exec such that the target process immediately gets it enabled for all VMAs. Yes that is the case for us as well, For us its mostly going to be a, i.e. exec_invoke called by systemd. But b will be good as well. > >> For having point 1, I think we will still need extra mm->flags, i.e. MMF_VM_THP_MADVISE/DEFER/ALWAYS/NEVER. > > Yes, and it's unclear what we really want here. Let me make a v2 and we might be able to have a better discussion once its done. I will move it to RFC. > >> >> I think it would have the same affect as what this patch is trying to do? But would be just more >> expensive in terms of both code changes and the cost of the actual call as you now have to walk >> all vmas. On the other hand you wont need the below diff in from v1. I do feel the current approach >> in the patch is simpler? But if your point 3 is better in terms of code maintainability, happy to make >> it the change to it in v2. > > Yes. Having a toggle that > > a) Changes the default of new VMAs to be VM_HUGEPAGE > > b) Modifies all existing VMAs that are not VM_NOHUGEPAGE to be VM_HUGEPAGE > > c) Is inherited during fork+exec > > Would not add any additional checks in our already-complicated THP allocation logic, it simply changes the default/value of VM_HUGEPAGE. > > > At least to me, this sounds like better semantics. Would that make your use case happy? > Yes, this would work for us. Let me try and make this work in the way you described and also make it work for MADVISE and NEVER, will send that in v2. Thanks for the feedback!!