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[109.81.92.13]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-a868f433671sm94947366b.128.2024.08.22.02.59.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 22 Aug 2024 02:59:49 -0700 (PDT) Date: Thu, 22 Aug 2024 11:59:48 +0200 From: Michal Hocko To: Linus Torvalds Cc: David Hildenbrand , Barry Song <21cnbao@gmail.com>, Yafang Shao , 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 Subject: Re: [PATCH v3 0/4] mm: clarify nofail memory allocation Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam03 X-Rspam-User: X-Rspamd-Queue-Id: C041B18001F X-Stat-Signature: whwp99jduu1zsq315qr38sdnnisqj85x X-HE-Tag: 1724320791-961083 X-HE-Meta: U2FsdGVkX1+n2SC5tz7RYlytZCHhIVqY2GIOA+mZL3LcB2E4zfSqbc8ePenklAWNHrbk30vWHjuNMARVkzOzrwxjJW4Ynd9C/RV/7McIKeE/oOB3zVEnLdBQsUbeYnDBdLlKhjQrD5sznfYrlgn5P5hP9eXenoUpXqGLFJMSJDWj2zuqfiNZUYAGg5YAyUx3ZOKUoU0UAfloxCNOdBmf88paJxY9fvhsNb93rCaUTNwdZ+yvZnEJIAA3QJjb9s4JMFnPf9+n3pSBRg/VrLXlYePObGEVfAqW/LRRyepWoIWaeC3TRn2TsELkMsG0CtTrcA38vGNUc8okLZunFac0ES7O5A0sAcNYs5eqMWKQgk7gwHUWN4uOsorr5PDdkGsuJwj5q7K/qkKOwOUXqrm0IZ4ezndZOmU9Kb24nBsaj9A8ZDw6aI4JXfA7BHfv6V2KvFlQG2vc1ez/sD4eZmQgqbo8wMYbJu61JGpYKrYugprkJiG1EDX+jkpRYzRbQ/CzqHH2VSTFrH1iZmpDNunW8cE9aByaJgpzXCGnLH1iKThG8wvd5KEskFnrSfwTGiFsd7hnmB6PDNJeM7NJT5nd2OarNLQFErTCkFFKYKZXPiwsX+YEqeRblzp27jki8Hc0tr+G4CEaJ6DRdNKxnzCNaVEiugiScVxYhZdfN7K0E/SUaEj8iDKqOrblNk5b9r07ozQOZyrWXuSwL9hKOr4RM50DarEPafemqKxwdPcu7+/k4ctYxyle16lGT9vbh8/GdhkMGxLDiur5DPl/oragQqdy72aJEwr5PowFNP4FtmNlhC1/xQSwxdTU/Z/7Kssjw5kGXbBPqvUBjGONreda7ALn4g3g5l0wopW36xBAf2U0Ilp7+NpRvw2KX738B2T1ruHvW5cSLKyymdVdYn/w092+1Qtcvl2AFdwL1mIYBlLQmW3aXnLfoywuxuTCf9RBi+oLWCyRZMfszJJb3DB ofGkWyaa ISl1sg3tYQ4TGm4Kif2wBBygQ8i6rrtYcYpZn1HJHA3DWnBIZvDTodaorW4KOQj36LU/6Os2MAMe2GPpuqNoO8xIreOe4Huik6O5Z73vfiVUqiKKZ37rTjulrftMfkH8gkIyXOO9f6I1vSJpt7aUkQVNdAHtub0+tIq/A/+0P3ctb0BvS6+y4ZWbXGA+/Np5KccYRm7yIN8A2nY5U7h7UVjkhUHTFQ4ePEhbAsMDgSnCmVj40xitu/sYUTj0hGQb0Ems/WveCV6mz4nchVRY/8ygiQXll7S9ldhAUwo458aqYdu/zaRJcTWZFEAVfqpFRq9b1KTOr5FRQC+FarnV0A0Zsf0PldjXIZt4Lq76/3+D6H30= 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 22-08-24 17:44:22, Linus Torvalds wrote: [...] > And dammit, those kvmalloc() sizes need to be limited too. A number > like 24kB was mentioned. That sounds fine. Maybe even 64kB. But make > it *SMALL*. I am not particularly bothered by exact size for kvmalloc. There should be a limit all right, but whether that is 1MB or 64kB shouldn't make much of a difference because we do use 4kB pages to back those allocations anyway. Sure 32b is a different story because the vmalloc space itself is a scarce resource but do we care about those? > And make it clear that it will return NULL if somebody misuses it. What do you expect users do with the return value then? -- Michal Hocko SUSE Labs