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Howlett" , LKML , linux-mm@kvack.org, Andrew Morton , Lokesh Gidra , Alistair Popple Subject: Re: [PATCH] mm: Always sanity check anon_vma first for per-vma locks Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Rspamd-Queue-Id: A334D40009 X-Rspam-User: X-Stat-Signature: sg81dicnz3epmqa9r6c48j1frj68c6o9 X-Rspamd-Server: rspam03 X-HE-Tag: 1713198419-296244 X-HE-Meta: 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 TSdw2Bb3 mwpy4qiOhgqoVc8Ct1jWaJt06JZOEoxdmBz1tewCam7w9BlO3e9oCtVMOPUaF2iRdf63AbQpbFcos/SfopnzDVTqOIUQlBIOUtAmfDbzjtd4cEG7r+PBFpnj7Gx8TSZlYeufcvOHp1i/Yh2KaeFEiwD7I+HDcTFusBSM46wrtRmXJBNGg01nFdanlkTcDosakWfNMnxYl6kW1rajAbGfKC6PhWhchEmRCZ/lfdgl1lPN6A+rUc+FpxILnIsaocnHiCRGICjDu6V/B1VKBfa16jxXwceAI16tkVkp02p+PMzmWmpKyVZ+WyOfJsIC4dEx08BIlMJngCoGUVNg= 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, Apr 15, 2024 at 09:19:06AM -0700, Suren Baghdasaryan wrote: > On Mon, Apr 15, 2024 at 9:13 AM Matthew Wilcox wrote: > > The tcp vma is not file backed, but I'm pretty sure that COW is not > > something they want, so there's never an anon_vma. It's for pages > > that contain received TCP packets; ie it's mmaped TCP. > > I was following > tcp_zerocopy_receive()->tcp_zerocopy_vm_insert_batch()->vm_insert_pages()->insert_page_in_batch_locked()->validate_page_before_insert() > which errors out for PageAnon(page). So, I assumed this path works on > file-backed pages but I'm not familiar with this code at all. It turns out there are pages which are neither file nor anon ;-) I have a partial list here: https://kernelnewbies.org/MatthewWilcox/Memdescs but I don't even have TCP on that list. I haven't looked into what they need -- I don't think they need mapping, index, etc, but I need to figure that out.