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[109.81.94.157]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-a79bc5a3ae8sm529783866b.30.2024.07.18.01.32.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 18 Jul 2024 01:32:50 -0700 (PDT) Date: Thu, 18 Jul 2024 10:32:49 +0200 From: Michal Hocko To: Barry Song <21cnbao@gmail.com> 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> Subject: Re: [PATCH RFC] mm: warn potential return NULL for kmalloc_array and kvmalloc_array with __GFP_NOFAIL Message-ID: References: <20240717230025.77361-1-21cnbao@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 48060160002 X-Stat-Signature: u6o9z1peudrpz6r5as4nfe9emsbda5d4 X-Rspam-User: X-HE-Tag: 1721291572-95212 X-HE-Meta: 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 TKWbaZDm 6PB/VyGlsgNLntzoedyYY1Ift/P4O9uMRR5dj/859c0f9Imk1ZBnZzw4ugj9e+1N47wIWX5zYfXtmKQtBVmoDXIkNpDBmlBbEnRLJ9Hi2urxtzl3Aa2UJ18O57zuxpgoYYpS5eTQ4FQ8k9vzaPNU1IeDCJfq13f35W4MuhGLMFwJtxOFek0Z9VkjpVKZ4aWQ+mQIvgkCezX9tgdnWs59KT6XTGrG4mwhMCxBCjkGuVifDNeOSrG5yHm3YDSedYS1iyjBfr1Sfq5UV59bGuiBppBlPkwMiyASkHeVdjSQZn5mf2nlqdMQnyWjvmxKdKffza5A8gHyWb1yFYLYzyiC9rJvmxranTtrnYLfqnmYL3qrBh9s4HSXN6eWV1oDy10lJSCQkxsyqN8WtWL2PEJ67uBX9Iw== 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 18-07-24 20:18:02, Barry Song wrote: > So the purpose is making sure the semantics - NOFAIL means no failure > and we don't need to check ret. If we can't really succeed, it should throw > a BUG to stop any potential exploits. This would require to panic consistently on failure in all allocator path that can bail out. E.g. page allocator on GFP_NOWAIT|GFP_NOFAIL req. not sure how many more. -- Michal Hocko SUSE Labs