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 DE3F0C3DA4A for ; Mon, 19 Aug 2024 13:05:26 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 2A0A86B008A; Mon, 19 Aug 2024 09:05:26 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 250F46B008C; Mon, 19 Aug 2024 09:05:26 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 1184E6B0092; Mon, 19 Aug 2024 09:05:26 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id E0F6B6B008A for ; Mon, 19 Aug 2024 09:05:25 -0400 (EDT) Received: from smtpin14.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 6E9A71A12B0 for ; Mon, 19 Aug 2024 13:05:25 +0000 (UTC) X-FDA: 82469016210.14.BA75771 Received: from mail-oi1-f170.google.com (mail-oi1-f170.google.com [209.85.167.170]) by imf27.hostedemail.com (Postfix) with ESMTP id 93C1240002 for ; Mon, 19 Aug 2024 13:05:23 +0000 (UTC) Authentication-Results: imf27.hostedemail.com; dkim=pass header.d=gmail.com header.s=20230601 header.b=C6MebFeZ; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf27.hostedemail.com: domain of 21cnbao@gmail.com designates 209.85.167.170 as permitted sender) smtp.mailfrom=21cnbao@gmail.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1724072637; 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=t/8M/g7fqE01VwwYaYDweAywXeYFLeqwtlEF1ZaGpk4=; b=b48M1d3rzKodVn6p5hXy9htJzd80oeNfR+o3yhy+BcsNZ0MlzyrY67uloCIHsc3z5QTyRM NDvQhlP69/IaTYs/A0isK3Pf+/L01klI1WA785jqoTn+j+H2CrorEJjCO+ZxZjewyRDz1z NIVn5K/ojOYsV4ycE4j/ESFezJ5I9tM= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1724072637; a=rsa-sha256; cv=none; b=wBrRwM7YTCPYwy83ggdbckynUl59YeP+01jLVN1EGwlQsVNabKji57vlhCwj8pRYzY7K6t r7iYzw0ZKBsoUCKtjDkOJZn8ys0OPWlFIuftSamc8NYrawGR+1ZzNPaghbLS4Xz49psYiZ fj6s7YDUw0CyFTsyQPhud3Zv6GXr4ko= ARC-Authentication-Results: i=1; imf27.hostedemail.com; dkim=pass header.d=gmail.com header.s=20230601 header.b=C6MebFeZ; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf27.hostedemail.com: domain of 21cnbao@gmail.com designates 209.85.167.170 as permitted sender) smtp.mailfrom=21cnbao@gmail.com Received: by mail-oi1-f170.google.com with SMTP id 5614622812f47-3db1270da60so3056266b6e.2 for ; Mon, 19 Aug 2024 06:05:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1724072722; x=1724677522; 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=t/8M/g7fqE01VwwYaYDweAywXeYFLeqwtlEF1ZaGpk4=; b=C6MebFeZDdlzs6sUp6XvkC/+C4/O1sJc3TAWTd/PlkeDHADsHOvPKCX961dp3PkMmZ dMGSTo3x/oe2HZWwmv/zdik0GwCBFiM3D4dTzwYBoSKNVme9qZSeglH1r8/tRwFIl78m TMmDQH0kK13zEmvolfW6DPYgkBlK2Jdx3WMLDtwGskebI8jSI5EkdNOdnDIVgrl8jEir 4S2Hsc3UXx13Nulpi3Np67l6l7e3ZJHypuJounSnvrKq1R2IFJDHFwziLFe5Lnj5Pd4Z iHs7+/Ax6HUuTyIWQyuIzYNRM47w235lCo8nY+ADbdLCBsnjrGSc2ch99OggJyshxILp m52A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1724072722; x=1724677522; 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=t/8M/g7fqE01VwwYaYDweAywXeYFLeqwtlEF1ZaGpk4=; b=nuH61MfKX5dTon5Ir3gXCRdyzDAtDxdsdPFcHDvCRtwxAThFoCRYW3ZdUp39hAvL6X kTlukQzyoavpbPK4auedjoY86dEMbTJ2rdSeEufkP2sIQGES0S+FiTqv8iN5D/Nc6Pwn YoRDj98prlwcMDFNX0SrtG2I0kYSxOrX86RzsVWdOJ4S30bzz8mlCRi/1sJBXmJR/mIm lTrVPgt9qLBRzfn0RGVnPU6PD/xrkGZ+/G+Wniyf0V42tmAN5/cjLyfHd3xqm1PTDXUB 5DlT2Bxl0ULU7Zkc6e2IGi+oqDBA2xJZksd3/mKU0KWluMR5MTG5f+YXiWFEobfrbmtz 5zMQ== X-Forwarded-Encrypted: i=1; AJvYcCVGtxkcz2JOF7z+QfzK5wgKfm5P7wpfvcPGTQP/mSEoGj975oWCKaFwf56gEEBU+MCs7TR4tz4ByqLnpMBTAWhZEv0= X-Gm-Message-State: AOJu0YzZJHlkGjOnhC0QIXkJHuMMPcCIsVmayi6hVjk9mrFRoCzkSIYG 1Y3I05UQuvj+fqftrLD5BZC+2ARBcHeA9lpziMuzbdm5SsKmBXZvqAvC8h2v/qmUWSZXYnzO7vG X3y6WoX89NvaPE0mMrkzOFnmYLI8= X-Google-Smtp-Source: AGHT+IF+JXI/F7OpCZMQlNI028X3cJz1MKS7sgQJvdmUOiyv7sBO0EGsiFnw9O36MFlLrsrjhATXZC4U/psLN+bN1oQ= X-Received: by 2002:a05:6358:5927:b0:1b1:ac2e:c50e with SMTP id e5c5f4694b2df-1b393199981mr1474341155d.9.1724072722410; Mon, 19 Aug 2024 06:05:22 -0700 (PDT) MIME-Version: 1.0 References: <20240817062449.21164-1-21cnbao@gmail.com> <20240817062449.21164-4-21cnbao@gmail.com> <5654b71c-1d9d-4c48-b28b-664662da8897@redhat.com> <416ac265-ced2-4f90-a347-0a256edf7fdf@redhat.com> <54a4619d-e826-465e-9a0f-0a8f37798e15@redhat.com> <20240819124924.GA7642@lst.de> In-Reply-To: From: Barry Song <21cnbao@gmail.com> Date: Tue, 20 Aug 2024 01:05:11 +1200 Message-ID: Subject: Re: [PATCH v3 3/4] mm: BUG_ON to avoid NULL deference while __GFP_NOFAIL fails To: David Hildenbrand Cc: Christoph Hellwig , 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, mhocko@suse.com, penberg@kernel.org, rientjes@google.com, roman.gushchin@linux.dev, torvalds@linux-foundation.org, urezki@gmail.com, v-songbaohua@oppo.com, vbabka@suse.cz, virtualization@lists.linux.dev, Lorenzo Stoakes , Kees Cook , =?UTF-8?Q?Eugenio_P=C3=A9rez?= , Jason Wang , Maxime Coquelin , "Michael S. Tsirkin" , Xuan Zhuo Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 93C1240002 X-Stat-Signature: 5xs6wqzhi8iab3b1ecpbcoo3szrhyzcy X-Rspam-User: X-HE-Tag: 1724072723-864666 X-HE-Meta: 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 yhsUEkol 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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 Tue, Aug 20, 2024 at 12:51=E2=80=AFAM David Hildenbrand wrote: > > On 19.08.24 14:49, Christoph Hellwig wrote: > > On Mon, Aug 19, 2024 at 02:33:06PM +0200, David Hildenbrand wrote: > >> It should all be caught during testing either way. And if some OOT mod= ule > >> does something nasty, that's not our responsibility. > >> > >> BUG_ON is not a way to write assertions into the code. > > > > So you'd rather create exploits than crashing on a fundamental API > > violation? That's exactly what the series is trying to fix. > > I'd rather have a sane API that doesn't even allow this level of > flexibility with NOFAIL. yes, i have already sent a RFC enforcing direct_reclamation: https://www.spinics.net/lists/linux-mm/msg394659.html somehow, it is not ready yet. i think Christoph prefers scope api rather than GFP_NOFAIL which definitely has __GFP_DIRECT_RECLAIM set. I guess you know I have at least 5 series running, so it will happen soon though. > > But probably I'm missing more details here why this all has to be so > complicated ;) enforcing direct_reclamation is right and will work for a reasonable size. but for this overflow size, even if we enforce direct_reclamation in GFP_NOFAIL, we are still failing. > > -- > Cheers, > > David / dhildenb >