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[209.85.208.46]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-5bebbe7f3ccsm5800953a12.72.2024.08.19.10.17.40 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 19 Aug 2024 10:17:41 -0700 (PDT) Received: by mail-ed1-f46.google.com with SMTP id 4fb4d7f45d1cf-5bed68129a2so1299646a12.1 for ; Mon, 19 Aug 2024 10:17:40 -0700 (PDT) X-Forwarded-Encrypted: i=1; AJvYcCW6OnpgYCYvqhKWwnvo/QIAiXMQnlH19qCFfz/HX96sDoPvkKaGT3lY1hqQD7lP1W4DI6H+NBTTpuXSL4qpP0dsgaI= X-Received: by 2002:a05:6402:1e90:b0:5be:eb9b:b703 with SMTP id 4fb4d7f45d1cf-5beeb9bb98fmr5392382a12.2.1724087860673; Mon, 19 Aug 2024 10:17:40 -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> <5424dfa3-03db-4a82-a08e-fb31285774b3@redhat.com> In-Reply-To: From: Linus Torvalds Date: Mon, 19 Aug 2024 10:17:23 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v3 3/4] mm: BUG_ON to avoid NULL deference while __GFP_NOFAIL fails To: Michal Hocko Cc: David Hildenbrand , Barry Song <21cnbao@gmail.com>, 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, Christoph Hellwig , 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" X-Stat-Signature: ckjrydbmsjxb4iw6csyfamf5gu13axcq X-Rspamd-Queue-Id: DE81BC002F X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1724087863-68537 X-HE-Meta: U2FsdGVkX19PWna4yE3Svq5ikJz2YpWnDKAsSg0q9NYvpsAXM8Jz0gD26ITbxXqwHpNWjbgyaBPChXc1jf140vk+yC8zTcxGiICyg+dgxHnMi67i378ov1Bt5HhrusA0G5aS6CncOUVflPsX/HXs7z7rlpM8FcckB8RZ6Y1tnHmu4d7XDvUrzMjJDN38qm4AzvmDh02FbfL+65z4eWCrnbNh2D91f/jC5b5jYK0HBETxaEGrrmiGYQ6/nYizZJus8GVIsE1mwsqP7w+nFCTQd/wcvVlpjP4HiIzo1eO69VUict0ZJUjR5GRFIuyC2Qfj1Lz2Femyr/WMiJHcL6nmnCvUVHfdcwBV8+lz9AjZL+EWJZmEy62PBN5j96NVzeJHaO4H9LgmJoDS77xTiCN9rhpV9qtJZtnBq26rtYwfdCgzfzncUkGquZ2zhim6x5GJKFD4NxRDUDC5k/1Tt9G+x5k7Rz/c6vrP8BVEt5lwTfB50eLXbTQ6aP758n0euaeFIY6qt6Ptz9/sC1f3Nc7eGCoe9qc/eDeP5DVyycgn9HeFR8UPyI7O9T1EvV2q9YzlCDXW9xby6GgqJ7jcRy3T7hwBF33QAIiIrwtIXCLBXZZcYWxPjPKfGjeM1+ru0P6+J7Q61t6OEj/jdCUiBWF3nmRL9DCVPTx3GSsxQStN90PMbP9Kc0dYcM7H1m3EazY/2l3gOmAOztYyJ/blNqeXABDIRFydlnRoLDzH4D5AnjjM4GAsCtvJ6Ha9V9tM4pnmIk7ecr9DtKYw/gfuEb4CSJqyW1rq8DmaQWHygACCdUXAntjgfkrULm/NCgnCq1uNsExLnZ5UiznvMsacMQC7r4VmgioQ8UkA+7sH0uflMVHDBjixrFZzwX9nqdDpV7jhFC3dVhReH91Zue0hcJZonJSXjhqN7k5Z3u8UwM3XIzjKQpyV+XPqx6wymzZihQ46H03jYWrM4DjKClJjMt+ K5iXl/qN 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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 Mon, 19 Aug 2024 at 10:12, Michal Hocko wrote: > > Whether to BUG_ON or simply loop for ever in the allocator if somebody > requests non-sleeping NOFAIL allocation is a different story. Just return NULL. The bug isn't in the VM. It's in the caller. Don't take on other peoples problems. It was never valid to say "I want to allocate lots of memory and you can't fail". Don't validate that kind of bogus behavior, just tell them "you're bad" and return NULL. Linus