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 33689C282DE for ; Thu, 13 Mar 2025 08:44:55 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 4C58E280003; Thu, 13 Mar 2025 04:44:53 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 4754E280001; Thu, 13 Mar 2025 04:44:53 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 31739280003; Thu, 13 Mar 2025 04:44:53 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 171A1280001 for ; Thu, 13 Mar 2025 04:44:53 -0400 (EDT) Received: from smtpin23.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 3C021BA39D for ; Thu, 13 Mar 2025 08:44:54 +0000 (UTC) X-FDA: 83215892508.23.CFC6BC5 Received: from mail-wm1-f50.google.com (mail-wm1-f50.google.com [209.85.128.50]) by imf18.hostedemail.com (Postfix) with ESMTP id 382001C0015 for ; Thu, 13 Mar 2025 08:44:52 +0000 (UTC) Authentication-Results: imf18.hostedemail.com; dkim=pass header.d=suse.com header.s=google header.b=JBzA3JWC; dmarc=pass (policy=quarantine) header.from=suse.com; spf=pass (imf18.hostedemail.com: domain of mhocko@suse.com designates 209.85.128.50 as permitted sender) smtp.mailfrom=mhocko@suse.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1741855492; a=rsa-sha256; cv=none; b=m3pkwdJvNp6ALRGMwKyJfXjF1sYVI6jhazwPcV8RgtZYAT6+S2WCvqKbktQ1wq0xZqTHnq qBq8Y5IEYXhJOeFr9KgmnlwaVZvqVBaEn59W6EoBx/Has1gOoDQEPEkeo9IlOPnIeQDkQa EEI603jtjelv6GpBv2BWMSP2hAvnYcc= ARC-Authentication-Results: i=1; imf18.hostedemail.com; dkim=pass header.d=suse.com header.s=google header.b=JBzA3JWC; dmarc=pass (policy=quarantine) header.from=suse.com; spf=pass (imf18.hostedemail.com: domain of mhocko@suse.com designates 209.85.128.50 as permitted sender) smtp.mailfrom=mhocko@suse.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1741855492; 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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=8oSuQ5bCsZRMab/7sf0LHNteyynOseZc+tj2NZOxBKI=; b=LzybvJiOK6d57ewvsKC9etas8NEBgXo2cTojpd8Rkl9l5cHrrx1yiIR25lPM2nFI4P7Jaz 55CxEjrN92XO0yJj33B6l4QTRPe5xrqNmBYTfXd56ShA2F6nDatoi6oLpm9tu6+tiJfvyH rI4On/mEe5X+b9e69+DARFE6vsqtlmw= Received: by mail-wm1-f50.google.com with SMTP id 5b1f17b1804b1-43d0c18e84eso3747875e9.3 for ; Thu, 13 Mar 2025 01:44:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=google; t=1741855490; x=1742460290; darn=kvack.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=8oSuQ5bCsZRMab/7sf0LHNteyynOseZc+tj2NZOxBKI=; b=JBzA3JWCgwsWphyOjLfUSdBK73ntv3a8reuT8sc5iLwvvxIVdyqcrIfHY35GA9NXqH syqc68ubCfzqon8uiWnph4Lh5Ng+M+Zw9KvU5jHAbwB5qHn0ft7gv4Tk6tnbgWRNtRnJ DSCHsL9xa8sEbcgeRueZQ3mAX13IoNDIwl//gMTVvnnKVt5dXpft+o6ZSB0nQq5xX23S HayYZ0SUdk/WNaRK8VyrCRdL/Np7R6pfee6jzFLzbhZnxBNzadTYve56my1N2ifc1JPA +oFzf6AkAvcoNpiX5Zpjjsgdy0NTBDguqXrhffHn8x/lBnwno9X3idgbKNIjDEg5GYWT bJCg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1741855490; x=1742460290; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=8oSuQ5bCsZRMab/7sf0LHNteyynOseZc+tj2NZOxBKI=; b=gkDCSmOqlglYr0RBiITXPj12Cfaz1VteJwpI9v9A8Ec+RqaQqw588EbW9LGo05i2lN KwNQqZ2eJHXuUFl0UylpJkcwAGrJZG75vwlduV6LChm34vt12LkbBY2mSRF5Z+83W6xT Ew0SoMP2bRDmmizxoaViZ19RFM6Me/jmXFpaO6HzTccnVKgYID9m+9c/iWD0cknMhblj gLP/yRnceCk7GUVZYsjZ/zB1prcf9HdSVYU3Tq++sLGWJEFMaC+eCTthZ/lwbWhb6PM7 xREC2muwbBz9WJ3RiThcgRdLI2viiDeyzcG59Nzo3TiCIH0+4TtKirWKyjgH1TyBBbwa gk0A== X-Forwarded-Encrypted: i=1; AJvYcCUPXf8A3Da0zOv5K1Nz2ctYzuPi3CygRZvPV7jNStRvDiDlSMlAcr4K0nGLx8AAUL3GKac1p+hpZw==@kvack.org X-Gm-Message-State: AOJu0YwoRr1AYJhaxqBHqkM1cjJ8j6ImS1m6g9JVMCONtESlc8l1IaAw JH4oSQAV+WWBtCH2qVjLIhCnzlukTGYrptUCgRbRcW6PDPO0kvDSEKExN9923Tk= X-Gm-Gg: ASbGncv5RdY7/adyg+aTjwELr9xKkuOsCcGqHkuBjpPazF8If8iBEElKm724rWhcIWG 9aNoHg9B+5Q1ajAB442PR6N8LYcFM4sNH8RNWPenXC7uGMyMFQj0FPZZfyBbdOECntf1XOsz1lr CCKTo/DJ8NZcZjC/UfkC5oY0QVPNVE6YyJnmp/RIwjpHV7jeCB1OLT8JzevbHT+jp/9iTkkfpYD O4QIjIiF+z88XE622kai6o7SEJBsGksauCgxbeOadpWix5PGT+l5897E6t5kJeEa7/VEa6nfnZQ 1neMGS7Ou6MiT8ZvNXmM07eBZSL17fbaCn6pTvPQmjX4W+UxpLLmvXz7SQ== X-Google-Smtp-Source: AGHT+IF2WBcUxm2qMhuOccsrLef56PO1H1TCxjQU7ShnaGYX0WOxshTc3Iz502MmCBGFMin1Qcj6jQ== X-Received: by 2002:a05:600c:45c9:b0:43d:abd:ad1c with SMTP id 5b1f17b1804b1-43d0abdafd5mr40005465e9.6.1741855490618; Thu, 13 Mar 2025 01:44:50 -0700 (PDT) Received: from localhost (109-81-85-167.rct.o2.cz. [109.81.85.167]) by smtp.gmail.com with UTF8SMTPSA id 5b1f17b1804b1-43d0a8d1666sm46259995e9.40.2025.03.13.01.44.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 13 Mar 2025 01:44:50 -0700 (PDT) Date: Thu, 13 Mar 2025 09:44:49 +0100 From: Michal Hocko To: Shakeel Butt Cc: Vlastimil Babka , Alexei Starovoitov , Andrew Morton , bpf , Andrii Nakryiko , Kumar Kartikeya Dwivedi , Peter Zijlstra , Sebastian Sewior , Steven Rostedt , Hou Tao , Johannes Weiner , Matthew Wilcox , Thomas Gleixner , Jann Horn , Tejun Heo , linux-mm , Kernel Team Subject: Re: [PATCH bpf-next v9 2/6] mm, bpf: Introduce try_alloc_pages() for opportunistic page allocation Message-ID: References: <20250222024427.30294-1-alexei.starovoitov@gmail.com> <20250222024427.30294-3-alexei.starovoitov@gmail.com> <20250310190427.32ce3ba9adb3771198fe2a5c@linux-foundation.org> <4d75c5a8-a538-4d7d-aaf4-8ecf1d1be6b9@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam07 X-Rspam-User: X-Stat-Signature: 9g5iacgsm4im4ooqzwcdxxxs4fhm3r4q X-Rspamd-Queue-Id: 382001C0015 X-HE-Tag: 1741855492-155999 X-HE-Meta: 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 jxXONvMs HUCBveqscQz2DY7h33PALqHUV8z9ygqKgUhuD0REfjc+JzVgy9CzMS+S8HcwrClFoKLruVSOMbhEyjDoCfJHVNMGhd6+TW0bxidIXeOrmggokEpyJsynJ00N9oeE1GAqYvUwev89G7RJf/43e/9xUxr2FFepdvhRwh+bOJOaNs3Bglpubq1Ha9vgPlwqbQFZRxCgLDLzAalcPq31XAKIZR6RKYc0Ofs97MXGleTzdnJjBI730loSMSXWpasUjpKrQna0BKq1Cei7K5nFz4LKOi7RrDFCICfbHPqAMPcTF9ea533iaBcFMU8Zu0J5xdDzFzPeG1RxEqI5yrLeseXfan8DTS23xKH0qP0tLL3UlmBVK6GFb0JTrhiIzpWDMiclZ320IKZkB1J4liFhDcd4kTItkTGxEUui8Pa4DKOm3jt0+xi/nVrRwe0nqTw== 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 12-03-25 12:06:10, Shakeel Butt wrote: > On Wed, Mar 12, 2025 at 11:00:20AM +0100, Vlastimil Babka wrote: > [...] > > > > But if we can achieve the same without such reserved objects, I think it's > > even better. Performance and maintainability doesn't need to necessarily > > suffer. Maybe it can even improve in the process. E.g. if we build upon > > patches 1+4 and swith memcg stock locking to the non-irqsave variant, we > > should avoid some overhead there (something similar was tried there in the > > past but reverted when making it RT compatible). > > In hindsight that revert was the bad decision. We accepted so much > complexity in memcg code for RT without questioning about a real world > use-case. Are there really RT users who want memcg or are using memcg? I > can not think of some RT user fine with memcg limits enforcement > (reclaim and throttling). I do not think that there is any reasonable RT workload that would use memcg limits or other memcg features. On the other hand it is not unusual to have RT and non-RT workloads mixed on the same machine. They usually use some sort of CPU isolation to prevent from CPU contention but that doesn't help much if there are other resources they need to contend for (like shared locks). > I am on the path to bypass per-cpu memcg stocks for RT kernels. That would cause regressions for non-RT tasks running on PREEMPT_RT kernels, right? -- Michal Hocko SUSE Labs