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Received: from willy by casper.infradead.org with local (Exim 4.98 #2 (Red Hat Linux)) id 1slfbc-00000000D4M-2NwD; Wed, 04 Sep 2024 02:18:48 +0000 Date: Wed, 4 Sep 2024 03:18:48 +0100 From: Matthew Wilcox To: John Hubbard Cc: Suren Baghdasaryan , Andrew Morton , kent.overstreet@linux.dev, corbet@lwn.net, arnd@arndb.de, mcgrof@kernel.org, rppt@kernel.org, paulmck@kernel.org, thuth@redhat.com, tglx@linutronix.de, bp@alien8.de, xiongwei.song@windriver.com, ardb@kernel.org, david@redhat.com, vbabka@suse.cz, mhocko@suse.com, hannes@cmpxchg.org, roman.gushchin@linux.dev, dave@stgolabs.net, liam.howlett@oracle.com, pasha.tatashin@soleen.com, souravpanda@google.com, keescook@chromium.org, dennis@kernel.org, yuzhao@google.com, vvvvvv@google.com, rostedt@goodmis.org, iamjoonsoo.kim@lge.com, rientjes@google.com, minchan@google.com, kaleshsingh@google.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-modules@vger.kernel.org, kernel-team@android.com Subject: Re: [PATCH v2 6/6] alloc_tag: config to store page allocation tag refs in page flags Message-ID: References: <20240902044128.664075-1-surenb@google.com> <20240902044128.664075-7-surenb@google.com> <20240901221636.5b0af3694510482e9d9e67df@linux-foundation.org> <47c4ef47-3948-4e46-8ea5-6af747293b18@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <47c4ef47-3948-4e46-8ea5-6af747293b18@nvidia.com> X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: D2D0E80003 X-Stat-Signature: uazaner9krpo8tmy83eppyikq1y4c34m X-Rspam-User: X-HE-Tag: 1725416360-229083 X-HE-Meta: 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 8LeVjlPy rEe2pBAFJ/IYFiCqmyDr+hQnwIp1OSy6TaYBAyXBXMfPzipXdFt4W4RPZBZwiFVRkBcBGr5tEVQ7GpoCfvcpg9WmD6Io7/BILtMWSX8G2VFMhnqREvBKOdk6pUFnFHV8fDfgd9g8hyCuv9ziqaSd31s+UOUGYkSXiD9LQYTfoVH58WYZJAogcukxkpnIGs/tZANGCKpttOnD6HXe58MMe2JNbfRMpyBRBcIeHKGin7O6PRmU3CtoQhF8F6TfIA8tPnoqkCUgvsjKuA4Esdud3axA3DQ== 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 Tue, Sep 03, 2024 at 06:25:52PM -0700, John Hubbard wrote: > The more I read this story, the clearer it becomes that this should be > entirely done by the build system: set it, or don't set it, automatically. > > And if you can make it not even a kconfig item at all, that's probably even > better. > > And if there is no way to set it automatically, then that probably means > that the feature is still too raw to unleash upon the world. I'd suggest that this implementation is just too whack. What if you use a maple tree for this? For each allocation range, you can store a pointer to a tag instead of storing an index in each folio.