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 07A20C3DA4A for ; Thu, 22 Aug 2024 11:58:53 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 557286B02D5; Thu, 22 Aug 2024 07:58:53 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 5053D6B02D8; Thu, 22 Aug 2024 07:58:53 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3A6E36B02D7; Thu, 22 Aug 2024 07:58:53 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 181DE6B0151 for ; Thu, 22 Aug 2024 07:58:53 -0400 (EDT) Received: from smtpin15.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id B4E70415AE for ; Thu, 22 Aug 2024 11:58:52 +0000 (UTC) X-FDA: 82479734904.15.CE0A7B8 Received: from mail-ed1-f50.google.com (mail-ed1-f50.google.com [209.85.208.50]) by imf16.hostedemail.com (Postfix) with ESMTP id 8EB7C180005 for ; Thu, 22 Aug 2024 11:58:50 +0000 (UTC) Authentication-Results: imf16.hostedemail.com; dkim=pass header.d=cmpxchg-org.20230601.gappssmtp.com header.s=20230601 header.b=t1AxfGzE; spf=pass (imf16.hostedemail.com: domain of hannes@cmpxchg.org designates 209.85.208.50 as permitted sender) smtp.mailfrom=hannes@cmpxchg.org; dmarc=pass (policy=none) header.from=cmpxchg.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1724327867; 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=k6+44GVv5VoR6gJL6+MDhdHhaquWcMnYUrv1YK4tTF8=; b=Baxz7Xt1BpGmqH0tXgB+g7FyyLhpqv3opIhiS5qjr+OaoyZWZmkLvu0glvOzKM3C9Q0C/q ins61QuZcoFQTyj4I0nTdMZe9lHspxh0RVqg3qpJjpP3YyALG1ETVdbk23TjrLf9F1a7pw M//SpJsUXGWLIgaJLfkrUpHzLyfAkvg= ARC-Authentication-Results: i=1; imf16.hostedemail.com; dkim=pass header.d=cmpxchg-org.20230601.gappssmtp.com header.s=20230601 header.b=t1AxfGzE; spf=pass (imf16.hostedemail.com: domain of hannes@cmpxchg.org designates 209.85.208.50 as permitted sender) smtp.mailfrom=hannes@cmpxchg.org; dmarc=pass (policy=none) header.from=cmpxchg.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1724327867; a=rsa-sha256; cv=none; b=FXCisWIzDpYoGeLGiaNcHsDDhCf85nKLIaLwuvH000u2FlWS3EUzzsieO84khoxbjR2lng Fj0fR0DhSBEFTHU7nkrMXp6V6B/a403yv4ixc0Iuyghu7cqPavwtqEXXx0+vm/JNHxzUVu 0tFCXXhEv5Qp1BmVXsAtxuWcZ+NI1xA= Received: by mail-ed1-f50.google.com with SMTP id 4fb4d7f45d1cf-5bb85e90ad5so765711a12.3 for ; Thu, 22 Aug 2024 04:58:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cmpxchg-org.20230601.gappssmtp.com; s=20230601; t=1724327929; x=1724932729; 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=k6+44GVv5VoR6gJL6+MDhdHhaquWcMnYUrv1YK4tTF8=; b=t1AxfGzEgM3CWKDntswYjdwl3dbgQN3a/Gb/iiGTqvvceLugQ7VH9Ly84xykHi24DN dR+BDuLsWWnV+AQHum9iPe/2aaUq+bnDoZFkh9uyD4O4LGAS58tvIYH8OSGGdODLRX+8 TzdirNNiBB8lR0YxcKg7ZLHbHwAHRwvUdiXHr3ZKgKosJY4QZqp3iyrl28Nf32nVHdLm tQWXl2loO23TY/A7qt0IIG1eYqbRLiex/E9NEw+B7UNNgYs/bO5FWxmrFHGrfhnMtujO gq/RYoRd9eRdnG9bAL9JylLPtUrL7D2VY7rzv0LlH9Cpju5PztEn5lqZccnnAizFz9Nj DlCg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1724327929; x=1724932729; 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=k6+44GVv5VoR6gJL6+MDhdHhaquWcMnYUrv1YK4tTF8=; b=gxvKCN9RFp8hjOO+uHi21I4a5wUryG6LDlfdqo0EvSdNIyAOOz+ldAEA0++QQct2pM ttPZwCV/1WG3k+j15yrZAT1SQNs6SKjH5cLNePmD8vio1O2WfabLZeRmN4PaxQBZXsQT 75kCtdgir0gHq9J2GC79iKjHOA08xWVq/1Km4QItH/nLPr0ihAUWAyPv1EXYTZboMGJJ 2r80ZfaGWgPanuoUgjcP6xDdIiChC4KCO/09GrEN4Btu56ENfdZJ+49AjnjY2xwIeb7A gxw0T9j0c61zaPlm4+6YhNkgMaMlv/0huo/WcWJvQSd738JUOTtnn4+UrnGXS7KLzvLe 4lqg== X-Forwarded-Encrypted: i=1; AJvYcCWfwVd1YHgOHVARor5BJ8KoY8lerJVmmLvpB3rkd6U9BdZwx5vAyYbMC2cF4SgDOjnPhurEb6mvmg==@kvack.org X-Gm-Message-State: AOJu0YzokY0jUoI7LKYtQfCSiD/Om1LWzUOte7fJtheIa1gAwa+M5Wka MhuZVaX2J78VzN2AOAmf88Nit6nXPRxhnpDQhiZAYpiDyGqtcNa/CS+e+USLRgU= X-Google-Smtp-Source: AGHT+IG13r4mxQnlEshp3lwVpXH9TCnF216rQVlMjsJtxd5sDVF4AHb7gNJExDhrJunr62kk0Mk8dQ== X-Received: by 2002:a05:6402:d08:b0:5be:d9ac:c776 with SMTP id 4fb4d7f45d1cf-5c0792b163cmr758523a12.38.1724327928682; Thu, 22 Aug 2024 04:58:48 -0700 (PDT) Received: from localhost ([2a02:8071:8280:d6e0:e324:b080:c95e:f348]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-5c04a4c59afsm836434a12.78.2024.08.22.04.58.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 22 Aug 2024 04:58:48 -0700 (PDT) Date: Thu, 22 Aug 2024 13:58:42 +0200 From: Johannes Weiner To: Linus Torvalds Cc: David Hildenbrand , Michal Hocko , Barry Song <21cnbao@gmail.com>, Yafang Shao , akpm@linux-foundation.org, linux-mm@kvack.org, 42.hyeyoo@gmail.com, cl@linux.com, hailong.liu@oppo.com, hch@infradead.org, iamjoonsoo.kim@lge.com, penberg@kernel.org, rientjes@google.com, roman.gushchin@linux.dev, urezki@gmail.com, v-songbaohua@oppo.com, vbabka@suse.cz, virtualization@lists.linux.dev Subject: Re: [PATCH v3 0/4] mm: clarify nofail memory allocation Message-ID: <20240822115842.GA352372@cmpxchg.org> References: <59e90825-4efa-4384-8286-06c0235304dc@redhat.com> <4df58ef1-b379-484a-aa5d-ef77a1200c63@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Stat-Signature: jhdoehku8rr95jucci1w55igaqq1bw3k X-Rspam-User: X-Rspamd-Queue-Id: 8EB7C180005 X-Rspamd-Server: rspam02 X-HE-Tag: 1724327930-113953 X-HE-Meta: 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 VnrACLEU 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 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 Thu, Aug 22, 2024 at 05:53:22PM +0800, Linus Torvalds wrote: > On Thu, 22 Aug 2024 at 17:43, David Hildenbrand wrote: > > > > So on the buddy level, that might mean that we limit it to a single > > page, > > Actually, for many SLUB allocations, you probably do have to accept > the small orders - the slab caches are often two or four pages. > > For example, a kmalloc(256) is an order-1 allocation on a buddy level > from a quick look at /proc/slabinfo. It will try higher orders to reduce fragmentation (and mask out NOFAIL on those attempts), but it can fall back to the minimum size required for the object, i.e. get_order(size). > So it's not necessarily only single pages. We do handle small orders. > But it gets exponentially harder, so it really is just the small > orders that work. Agreed. > Looks like slub will use up to order-3. That smells like an off-by-one > to me (I thought we made 0-2 be the "cheap" orders, but maybe I'm just > wrong), but it probably is still acceptable. It's 0-3. We #define PAGE_ALLOC_COSTLY_ORDER 3, but it's exclusive - all the order checks are > costly and <= costly.