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 DC538C3DA4A for ; Mon, 19 Aug 2024 13:10:36 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 5D9AE6B0083; Mon, 19 Aug 2024 09:10:36 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 563406B0085; Mon, 19 Aug 2024 09:10:36 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3676F6B0088; Mon, 19 Aug 2024 09:10:36 -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 14BE06B0083 for ; Mon, 19 Aug 2024 09:10:36 -0400 (EDT) Received: from smtpin06.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 9C6041C3A86 for ; Mon, 19 Aug 2024 13:10:35 +0000 (UTC) X-FDA: 82469029230.06.483BE51 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by imf29.hostedemail.com (Postfix) with ESMTP id 4677F120014 for ; Mon, 19 Aug 2024 13:10:33 +0000 (UTC) Authentication-Results: imf29.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=PPVbTZnG; dmarc=pass (policy=none) header.from=redhat.com; spf=pass (imf29.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=david@redhat.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1724072976; a=rsa-sha256; cv=none; b=ZaUb9Oky0Ckht76WOTTftlq4VUnGCzq9RXx+feul43Q7txUgvDy6dqhlVXWAw8pqJxyYpT xkarDs7geyd0FoNkQAbQkaRnRxOkmKpH4huPnyfCgkac5bKsSeh0u/hne+J44bGMT3q3+k LZX9dXHH9NKYGuw1wOKZiy87sO2qBko= ARC-Authentication-Results: i=1; imf29.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=PPVbTZnG; dmarc=pass (policy=none) header.from=redhat.com; spf=pass (imf29.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=david@redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1724072976; 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=XMNCLnzyp9nyIj6Go6iunaDZy1dWwAx3XctyX4fFYfU=; b=yNMcPSZO1L49tLNg6CqBOMSEwcuqWAjPiK8mCPHgrn9a3JI3GeSOWlGD3TlEi2nxiTiX/p yh37O9XRmerjXq4h7bjAq4lKQ+MDOKK5oOmKk4PjsH0pZ8V4tNGOoemfWKyHme8A2+IinD MRAyyjuT+fiFfjE5gV3Fao5coNf0Grs= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1724073032; h=from:from: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:autocrypt:autocrypt; bh=XMNCLnzyp9nyIj6Go6iunaDZy1dWwAx3XctyX4fFYfU=; b=PPVbTZnGue8ph1Gujikl2SviAGaK/5MLQBs5w9D08TaSr/lF/QT+TddFFQXb0WvEYd5b/B LnDUqt323OTh+qP6I+h76180lXrPy8s7yeePRr3aK623qR3JP/TsZpd/mqE/oobPQlH8MV H2OIqrEc9xRZQhrR7WM5wGVrA19UGOg= Received: from mail-ej1-f70.google.com (mail-ej1-f70.google.com [209.85.218.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-388-aE3QgUzuNne6Dq79iEB9Uw-1; Mon, 19 Aug 2024 09:10:31 -0400 X-MC-Unique: aE3QgUzuNne6Dq79iEB9Uw-1 Received: by mail-ej1-f70.google.com with SMTP id a640c23a62f3a-a7aa5885be3so307836366b.0 for ; Mon, 19 Aug 2024 06:10:30 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1724073030; x=1724677830; h=content-transfer-encoding:in-reply-to:organization:autocrypt :content-language:from: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=XMNCLnzyp9nyIj6Go6iunaDZy1dWwAx3XctyX4fFYfU=; b=PL+3DRbGc6jJeVu++GxudhF9x1dcqDT/GU9ZAkii66ISkSG3swRc2ka3B+2C8woby8 R0vliZgv9y9WXuuuzOb7kaN3El95Krgp/5ChQN0g0nRzV5BQVNrabLBn+//fxJQE+Npq y+lvudhAUy0MXWoU+XCMaOhwGVw3awirgHcV58mLgSNBJ0OThHTX4leW9O6KngmTvFjP CBzgJDydmPyp4BzuN2yc/S6wYiIEx5uzqY92R+PATFYZmVCiSKIr5NvuE958jF8Ww5gU keNGnJ32wjiL1PQqzhOGZr+qCEkffAiquSdYPD+qfXJjrQBZo3qrBx1bPhPXUD5QCJzw gY3w== X-Forwarded-Encrypted: i=1; AJvYcCVrm47TPGEmCpqB/xRcDvvaL8zxVxQgILu8Th0YCUoPIF3wSdo0Nmo3DtMigS2NvJ7uE88+009U+3cXxUFCD92RCoQ= X-Gm-Message-State: AOJu0YwCUTNxm/8Zw+749FqEcj3hX63OUqLJCxkuY7MG9b7yy1KpvzRz yIHyQQX7x7hwtcdWEgaubFX0RnOQ3qXf9JtXJ7wk7wc0Yjaxhd2cMaOtZh1ywsZQPnrA5qfum7F Vj+/sA7XH/2d/00uxDQqM7Q8pTuoaYOFzSpIBYfsgiTbEroD3 X-Received: by 2002:a17:907:60c9:b0:a77:cdaa:88a7 with SMTP id a640c23a62f3a-a8392a051fcmr703609066b.48.1724073029862; Mon, 19 Aug 2024 06:10:29 -0700 (PDT) X-Google-Smtp-Source: AGHT+IGUuPc29kIFzUFMwGrSs24EAR4+mUUsoaAz8tIBnTfe6Qlcloo3k73rngfy9Oc60/5MFxTcMg== X-Received: by 2002:a17:907:60c9:b0:a77:cdaa:88a7 with SMTP id a640c23a62f3a-a8392a051fcmr703607266b.48.1724073029345; Mon, 19 Aug 2024 06:10:29 -0700 (PDT) Received: from [100.81.188.195] (ipb218f908.dynamic.kabel-deutschland.de. [178.24.249.8]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-a8383935698sm628622366b.102.2024.08.19.06.10.27 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 19 Aug 2024 06:10:28 -0700 (PDT) Message-ID: <9f4fa8cf-df02-463d-9715-087a7cd6fc88@redhat.com> Date: Mon, 19 Aug 2024 15:10:27 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 3/4] mm: BUG_ON to avoid NULL deference while __GFP_NOFAIL fails To: Barry Song <21cnbao@gmail.com> 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 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> From: David Hildenbrand Autocrypt: addr=david@redhat.com; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZgEEwEIAEICGwMGCwkIBwMCBhUIAgkKCwQW AgMBAh4BAheAAhkBFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAl8Ox4kFCRKpKXgACgkQTd4Q 9wD/g1oHcA//a6Tj7SBNjFNM1iNhWUo1lxAja0lpSodSnB2g4FCZ4R61SBR4l/psBL73xktp rDHrx4aSpwkRP6Epu6mLvhlfjmkRG4OynJ5HG1gfv7RJJfnUdUM1z5kdS8JBrOhMJS2c/gPf wv1TGRq2XdMPnfY2o0CxRqpcLkx4vBODvJGl2mQyJF/gPepdDfcT8/PY9BJ7FL6Hrq1gnAo4 3Iv9qV0JiT2wmZciNyYQhmA1V6dyTRiQ4YAc31zOo2IM+xisPzeSHgw3ONY/XhYvfZ9r7W1l pNQdc2G+o4Di9NPFHQQhDw3YTRR1opJaTlRDzxYxzU6ZnUUBghxt9cwUWTpfCktkMZiPSDGd KgQBjnweV2jw9UOTxjb4LXqDjmSNkjDdQUOU69jGMUXgihvo4zhYcMX8F5gWdRtMR7DzW/YE BgVcyxNkMIXoY1aYj6npHYiNQesQlqjU6azjbH70/SXKM5tNRplgW8TNprMDuntdvV9wNkFs 9TyM02V5aWxFfI42+aivc4KEw69SE9KXwC7FSf5wXzuTot97N9Phj/Z3+jx443jo2NR34XgF 89cct7wJMjOF7bBefo0fPPZQuIma0Zym71cP61OP/i11ahNye6HGKfxGCOcs5wW9kRQEk8P9 M/k2wt3mt/fCQnuP/mWutNPt95w9wSsUyATLmtNrwccz63XOwU0EVcufkQEQAOfX3n0g0fZz Bgm/S2zF/kxQKCEKP8ID+Vz8sy2GpDvveBq4H2Y34XWsT1zLJdvqPI4af4ZSMxuerWjXbVWb T6d4odQIG0fKx4F8NccDqbgHeZRNajXeeJ3R7gAzvWvQNLz4piHrO/B4tf8svmRBL0ZB5P5A 2uhdwLU3NZuK22zpNn4is87BPWF8HhY0L5fafgDMOqnf4guJVJPYNPhUFzXUbPqOKOkL8ojk CXxkOFHAbjstSK5Ca3fKquY3rdX3DNo+EL7FvAiw1mUtS+5GeYE+RMnDCsVFm/C7kY8c2d0G NWkB9pJM5+mnIoFNxy7YBcldYATVeOHoY4LyaUWNnAvFYWp08dHWfZo9WCiJMuTfgtH9tc75 7QanMVdPt6fDK8UUXIBLQ2TWr/sQKE9xtFuEmoQGlE1l6bGaDnnMLcYu+Asp3kDT0w4zYGsx 5r6XQVRH4+5N6eHZiaeYtFOujp5n+pjBaQK7wUUjDilPQ5QMzIuCL4YjVoylWiBNknvQWBXS lQCWmavOT9sttGQXdPCC5ynI+1ymZC1ORZKANLnRAb0NH/UCzcsstw2TAkFnMEbo9Zu9w7Kv AxBQXWeXhJI9XQssfrf4Gusdqx8nPEpfOqCtbbwJMATbHyqLt7/oz/5deGuwxgb65pWIzufa N7eop7uh+6bezi+rugUI+w6DABEBAAHCwXwEGAEIACYCGwwWIQQb2cqtc1xMOkYN/MpN3hD3 AP+DWgUCXw7HsgUJEqkpoQAKCRBN3hD3AP+DWrrpD/4qS3dyVRxDcDHIlmguXjC1Q5tZTwNB boaBTPHSy/Nksu0eY7x6HfQJ3xajVH32Ms6t1trDQmPx2iP5+7iDsb7OKAb5eOS8h+BEBDeq 3ecsQDv0fFJOA9ag5O3LLNk+3x3q7e0uo06XMaY7UHS341ozXUUI7wC7iKfoUTv03iO9El5f XpNMx/YrIMduZ2+nd9Di7o5+KIwlb2mAB9sTNHdMrXesX8eBL6T9b+MZJk+mZuPxKNVfEQMQ a5SxUEADIPQTPNvBewdeI80yeOCrN+Zzwy/Mrx9EPeu59Y5vSJOx/z6OUImD/GhX7Xvkt3kq Er5KTrJz3++B6SH9pum9PuoE/k+nntJkNMmQpR4MCBaV/J9gIOPGodDKnjdng+mXliF3Ptu6 3oxc2RCyGzTlxyMwuc2U5Q7KtUNTdDe8T0uE+9b8BLMVQDDfJjqY0VVqSUwImzTDLX9S4g/8 kC4HRcclk8hpyhY2jKGluZO0awwTIMgVEzmTyBphDg/Gx7dZU1Xf8HFuE+UZ5UDHDTnwgv7E th6RC9+WrhDNspZ9fJjKWRbveQgUFCpe1sa77LAw+XFrKmBHXp9ZVIe90RMe2tRL06BGiRZr jPrnvUsUUsjRoRNJjKKA/REq+sAnhkNPPZ/NNMjaZ5b8Tovi8C0tmxiCHaQYqj7G2rgnT0kt WNyWQQ== Organization: Red Hat In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 4677F120014 X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: y8qfpsgqnjzwwo4h65c5nc5hoc7yyqqz X-HE-Tag: 1724073033-951236 X-HE-Meta: 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 sJbNtDhj 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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 19.08.24 15:05, Barry Song wrote: > On Tue, Aug 20, 2024 at 12:51 AM 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 module >>>> 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. That really sounds like the right thing to do, at least with the "direct reclaim" problem ... > >> >> 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. Right, someone requested something completely impossible. It's harder to do something here that doesn't return NULL. Except WARN_ON_ONCE() and loop for all infinity. -- Cheers, David / dhildenb