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 05B07C3DA5D for ; Fri, 19 Jul 2024 08:37:03 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 9214E6B008C; Fri, 19 Jul 2024 04:37:02 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 8D1666B0092; Fri, 19 Jul 2024 04:37:02 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 7C0906B0093; Fri, 19 Jul 2024 04:37:02 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 5BA766B008C for ; Fri, 19 Jul 2024 04:37:02 -0400 (EDT) Received: from smtpin10.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id F22AE12048A for ; Fri, 19 Jul 2024 08:37:01 +0000 (UTC) X-FDA: 82355847042.10.43D3B55 Received: from mail-qk1-f178.google.com (mail-qk1-f178.google.com [209.85.222.178]) by imf02.hostedemail.com (Postfix) with ESMTP id 3A5CC80003 for ; Fri, 19 Jul 2024 08:37:00 +0000 (UTC) Authentication-Results: imf02.hostedemail.com; dkim=pass header.d=gmail.com header.s=20230601 header.b="ieJha/PR"; spf=pass (imf02.hostedemail.com: domain of 21cnbao@gmail.com designates 209.85.222.178 as permitted sender) smtp.mailfrom=21cnbao@gmail.com; dmarc=pass (policy=none) header.from=gmail.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1721378199; 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=vl9mIUQlv6osF1blYeiEVjXk5SgyouWCikJXm+g5/9M=; b=aVVbu/OfP9DaJyb2S+uWVhxa0pQSGtlCPxkh9N6g04e8/Jwx56k8tLkohQeRxCnYEjlCMW sxAL0VD9ZCLsoEPGqfvtFC1XvmP3f7KSZQvwSUIvjrWjNQFaduC++jWEqCerkOaM9WVvkE 3mFkvacSRABDISdvFjGQyBa969m+YRI= ARC-Authentication-Results: i=1; imf02.hostedemail.com; dkim=pass header.d=gmail.com header.s=20230601 header.b="ieJha/PR"; spf=pass (imf02.hostedemail.com: domain of 21cnbao@gmail.com designates 209.85.222.178 as permitted sender) smtp.mailfrom=21cnbao@gmail.com; dmarc=pass (policy=none) header.from=gmail.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1721378199; a=rsa-sha256; cv=none; b=cafAkolDssQvEUP+THQssNV9JQ3WmH+zxqs2O3mFhTiTBa/7c8uTMg+hrq1Wt0HhQEsqMO q0FIffe8vH8dspBBCT39Ml2hgzYqx7vyeu0UX6vBiRZLTVysPOlXi+vsJz7zEyg8nt5ag0 5ga7/yHoGbT9eeUy3sG32VpkLAQ7K5w= Received: by mail-qk1-f178.google.com with SMTP id af79cd13be357-79f16cad2a7so77202285a.0 for ; Fri, 19 Jul 2024 01:37:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1721378219; x=1721983019; darn=kvack.org; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=vl9mIUQlv6osF1blYeiEVjXk5SgyouWCikJXm+g5/9M=; b=ieJha/PRNpJOk5doTBv4oUrk356yoPkDPMN6Lls9owQlQ2ZqjziCgfpgY6aeZFg23U OPVbxgYc6bbXzazPvcGk86hY8j7ezO1wZDXY9H+fcuonHesULYN0Z2M9oT+sz9Q0Yz0y FFKjuwGCq9rOUmNPrWovcoXN+GyI7lDgr+Dpw6teiO09XuewDd1CgbOM5wcgRJnMGueJ X4iKId/2E8NyB76fsUL5vvsPNKTw5sS9Mk0k+n0SoKnlXDrxSAVVqPP1rCg+cuNHAP4B USaF7/3qHxNpkzaeIhGL4442X3eMzsd7F2SnW61W9PpDGj7dIVhyCWKS3LRxLI/jXDPT 847A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1721378219; x=1721983019; 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=vl9mIUQlv6osF1blYeiEVjXk5SgyouWCikJXm+g5/9M=; b=s2+J8C3xKvc7wpgD+DjtI8AcrqY8kD0bQK4mVV6mouPN7MFTHl+52pqGxcxRZWmuwo jEHJR7k+1rCgu7kYEGs499589bx+XnJ06xTyumrC76YG097BZ+/1hGb0It1tbCTLsGyq Wxpy+kCIx9xB9T5X0Q8ulp3BjUYT7d0AFq0G44pguhTlIFQ4f6MxbRYk1K3JCDlS8fhR SkO/7IG3iJQt8rGjw/QJnf2vWc1S15Lhs/LqpSwog4YwQzgaiB3TIvYUhzCbBrvRVr9B 8WtxtAg+gvc4Tva/Ga/by7jPoXvcAd7eyQFkCXU6/6tokjFzrtPtvpQsU9ee1Q01jmQE 5qbQ== X-Forwarded-Encrypted: i=1; AJvYcCVYTrqtejfaRcgK4I7OHgn5EfXyuGXB6NpkjpdcRyOdWf+AwkxRpbEMlqSJ/1YX4AtjZeCvw+faVSgH0NNn8m9WnMs= X-Gm-Message-State: AOJu0Yy+EAuaWDMRaTDe5qiRzLbSyEwDPHxycjk/NhEK2h1KaaLR8wVp 3xx8Gg7qlIPEXJTnEee9Fla9GNuVBc6AT5pC8uJ7OXKCGTFI35TyHTt4sbCOd0ulcVUYPtzZT2C UpwOid9zFkkYU+RM44IXMLXIivMpb1c/n X-Google-Smtp-Source: AGHT+IFuJqzwSvXcs8RyBU4dlyw46TJt80TGRkrlIYJmRuiM6Avuwv64lj/oGrm1XE9cwA8gpF8MB4F1klaBtGyUAYU= X-Received: by 2002:a05:6102:3c8f:b0:48f:91cd:8c1a with SMTP id ada2fe7eead31-491597383c4mr8653435137.3.1721377733094; Fri, 19 Jul 2024 01:28:53 -0700 (PDT) MIME-Version: 1.0 References: In-Reply-To: From: Barry Song <21cnbao@gmail.com> Date: Fri, 19 Jul 2024 20:28:41 +1200 Message-ID: Subject: Re: [PATCH RFC] mm: warn potential return NULL for kmalloc_array and kvmalloc_array with __GFP_NOFAIL To: Michal Hocko Cc: akpm@linux-foundation.org, linux-mm@kvack.org, Barry Song , Uladzislau Rezki , Christoph Hellwig , Lorenzo Stoakes , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Vlastimil Babka , Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 3A5CC80003 X-Stat-Signature: ygin1jw1199yo667a85uiiwys7oxwnyd X-Rspam-User: X-HE-Tag: 1721378220-638757 X-HE-Meta: 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 UE28v0zv 1z9O/zKBPsBla3PX3mH2z7Q5ZPF3XpUFaAnQFKGeXRtv8M8u6YtXXpgAp0HBCfDjSTxFjiSst/IpeAR0zKETMow9P6Lc8SuBSSnS3iWmv2F8pwpS+eZC1mLfY3IIxvxCfoGTJWD0aNXXUY9ApLR3LiVkG1tqFdeyWDqHUoeZTF6dOZqS8AFq+DLPDY1scWxwhVqWwZP7zyry2T8leFkLKHrknxTdu0OFcit+9b6EqaiOpvjAh9dCoKdDz0MU5ydBXrDw9rJ4eHCeyQt1V/SoN3brNMJrRw8paBDMwk/NnZo6DyzYfsCLVJd9ixJBLkpipkDduRmZ2lq9/PCSmHkR778k0AlX2beavmEX651QF5fH69ZsSuYrLWFlk52UxoL5nOSQvKDM+TZPdrHJ7/B/f+UfgIxnIwaNpDaJzwyrz1XAvoyXWNeGWPHDKnclEJho6bkG1RQQ6aAe1I6VTMGobkKuaxhKQU7rJ6QzK 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 Fri, Jul 19, 2024 at 8:01=E2=80=AFPM Michal Hocko wrot= e: > > On Fri 19-07-24 19:51:06, Barry Song wrote: > > On Fri, Jul 19, 2024 at 7:42=E2=80=AFPM Michal Hocko = wrote: > [...] > > > It cannot reclaim itself and it cannot sleep to wait for the memory s= o > > > NOFAIL semantic is simply impossible. We have put a warning in place = to > > > > this is still "right" behaviour to retry infinitely at least according > > to the doc of > > __GFP_NOFAIL. > > I do not agree that implementing busy loop in the kernel is the right > practice! > > > I assume getting new memory by many retries is still > > possibly some other processes might be reclaiming or freeing memory > > then providing free memory to this one being stuck. > > No, I strongly disagree we should even pretend this is a supported > allocation strategy. NAK to any attempt to legalize it in some form. fare enough. I am not trying to legitimize it, just explaining what the documentation sa= ys. If it is illegal, we should clearly and firmly state that it is illegal, rather than pretending it is legal and returning NULL. This is also wrong. > > -- > Michal Hocko > SUSE Labs