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bh=g4KPVLzLbPyMxaXV5flTz0nx+fjmvrjrnSIFeRRKynM=; b=nGuD/bl5ND2dW5gW5dfBarKF8+Lrjl0xUi4XBmNTuqFvvcJrYI81/PYCvZaJulOTqwUOZP Zm4E8v6OufSCeeKKbqbK7/7r0VaD3L77Z5JhKDPuAWiMI5QitCHXoL687DGOvUUUnT+3tC 703z7JGNhg7TXY2zeIQ1HbjM4sPX4GE= ARC-Authentication-Results: i=1; imf11.hostedemail.com; dkim=none; dmarc=none; spf=pass (imf11.hostedemail.com: domain of byungchul@sk.com designates 166.125.252.92 as permitted sender) smtp.mailfrom=byungchul@sk.com X-AuditID: a67dfc5b-681ff7000002311f-21-67ff8464fd92 Date: Wed, 16 Apr 2025 19:20:15 +0900 From: Byungchul Park To: Jakub Kicinski Cc: willy@infradead.org, ilias.apalodimas@linaro.org, almasrymina@google.com, kernel_team@skhynix.com, 42.hyeyoo@gmail.com, linux-mm@kvack.org, hawk@kernel.org, netdev@vger.kernel.org Subject: Re: [RFC] shrinking struct page (part of page pool) Message-ID: <20250416102015.GA5520@system.software.com> References: <20250414013627.GA9161@system.software.com> <20250414015207.GA50437@system.software.com> <20250414163002.166d1a36@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; 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However, I need to resolve a curiousity > > > before starting. > > I don't understand what the question is but FWIW from my perspective > the ZC APIs are fairly contained, or at least we tried to make sure > that net_iov pages cannot reach random parts of the stack. > > Replacing all uses of struct page would require converting much more > of the stack, AFAIU. But that's best discussed over posted patches. Okay. Let's discuss it once posting patches. > > > Network guys already introduced a sperate strcut, struct net_iov, > > > to overlay the interesting fields. However, another separate struct > > > for system memory might be also needed e.g. struct bump so that > > > struct net_iov and struct bump can be overlayed depending on the > > > source: > > > > > > struct bump { > > > unsigned long _page_flags; > > > unsigned long bump_magic; > > > struct page_pool *bump_pp; > > > unsigned long _pp_mapping_pad; > > > unsigned long dma_addr; > > > atomic_long_t bump_ref_count; > > > unsigned int _page_type; > > > atomic_t _refcount; > > > }; > > > > > > To netwrok guys, any thoughts on it? > > > To Willy, do I understand correctly your direction? > > > > > > Plus, it's a quite another issue but I'm curious, that is, what do you > > > guys think about moving the bump allocator(= page pool) code from > > > network to mm? I'd like to start on the work once gathering opinion > > > from both Willy and network guys. > > I don't see any benefit from moving page pool to MM. It is quite > networking specific. But we can discuss this later. Moving code > is trivial, it should not be the initial focus. I think so. Byungchul