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([2620:10d:c092:600::1:72ea]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3b77e216516sm10225969f8f.72.2025.07.29.01.52.10 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 29 Jul 2025 01:52:11 -0700 (PDT) Message-ID: <7d7eb3cd-db7e-4a9e-8671-4185b716bbc8@gmail.com> Date: Tue, 29 Jul 2025 09:53:31 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] mm, page_pool: introduce a new page type for page pool in page type To: Byungchul Park Cc: Mina Almasry , linux-mm@kvack.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, kernel_team@skhynix.com, harry.yoo@oracle.com, ast@kernel.org, daniel@iogearbox.net, davem@davemloft.net, kuba@kernel.org, hawk@kernel.org, john.fastabend@gmail.com, sdf@fomichev.me, saeedm@nvidia.com, leon@kernel.org, tariqt@nvidia.com, mbloch@nvidia.com, andrew+netdev@lunn.ch, edumazet@google.com, pabeni@redhat.com, akpm@linux-foundation.org, david@redhat.com, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, vbabka@suse.cz, rppt@kernel.org, surenb@google.com, mhocko@suse.com, horms@kernel.org, jackmanb@google.com, hannes@cmpxchg.org, ziy@nvidia.com, ilias.apalodimas@linaro.org, willy@infradead.org, brauner@kernel.org, kas@kernel.org, yuzhao@google.com, usamaarif642@gmail.com, baolin.wang@linux.alibaba.com, toke@redhat.com, bpf@vger.kernel.org, linux-rdma@vger.kernel.org References: <20250728052742.81294-1-byungchul@sk.com> <20250729010410.GC56089@system.software.com> Content-Language: en-US From: Pavel Begunkov In-Reply-To: <20250729010410.GC56089@system.software.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Stat-Signature: 8gr3fop71earjhabpm79nqocy6unghin X-Rspamd-Queue-Id: 515CB100003 X-Rspamd-Server: rspam10 X-Rspam-User: X-HE-Tag: 1753779134-939362 X-HE-Meta: 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 pviT/J6s 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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 7/29/25 02:04, Byungchul Park wrote: > On Mon, Jul 28, 2025 at 07:49:30PM +0100, Pavel Begunkov wrote: >> On 7/28/25 19:39, Mina Almasry wrote: >>> On Mon, Jul 28, 2025 at 11:35 AM Pavel Begunkov wrote: ...>>> This may be my bad since I said we should check if it's 0 initialized. >>> >>> It looks like on the devmem side as well we kvmalloc_array the niovs, >>> and if I'm checking through the helpers right, kvmalloc_array does >>> 0-initialize indeed. >> >> I wouldn't rely on that, it's just for zcrx I do: >> >> kvmalloc_array(..., GFP_KERNEL | __GFP_ZERO); > > For net_devmem_bind_dmabuf(), __GFP_ZERO will add bigger overhead than > just assignment, 'niov->pp = NULL'. That's not a place where you should care about zeroing overhead. > I'd like to ask you if you are still good with __GFP_ZERO overhead > before going ahead. However, it might be easier for you to just assign it directly for devmem and let Mina add GFP_ZERO if he fancy the idea. -- Pavel Begunkov