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Peter Anvin" , Zi Yan , Dave Hansen , Lorenzo Stoakes , Andrew Morton , "Liam R . Howlett" , Jens Axboe , linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org, "Darrick J . Wong" , gost.dev@samsung.com, hch@lst.de, linux-kernel@vger.kernel.org, linux-mm@kvack.org, willy@infradead.org, x86@kernel.org, mcgrof@kernel.org Subject: Re: [RFC v2 0/2] add THP_HUGE_ZERO_PAGE_ALWAYS config option Message-ID: <625s5hffr3iz35uv4hts4sxpprwwuxxpbsmbvasy24cthlsj6x@tg2zqm6v2wqm> References: <20250522090243.758943-1-p.raghav@samsung.com> <6lhepdol4nlnht7elb7jx7ot5hhckiegyyl6zeap2hmltdwb5t@ywsaklwnakuh> <6894a8b1-a1a7-4a35-8193-68df3340f0ad@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6894a8b1-a1a7-4a35-8193-68df3340f0ad@redhat.com> X-Stat-Signature: dm17c5yys4jkkntnqwmdibj38gforiyu X-Rspamd-Queue-Id: EAE21100012 X-Rspam-User: X-Rspamd-Server: rspam02 X-HE-Tag: 1747917295-222489 X-HE-Meta: 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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: Hi David, > > config ARCH_WANTS_THP_SWAP > > def_bool n > > -config ARCH_WANTS_THP_ZERO_PAGE_ALWAYS > > +config ARCH_WANTS_HUGE_ZERO_PAGE_ALWAYS > > def_bool n > > +config HUGE_ZERO_PAGE_ALWAYS > > Likely something like > > PMD_ZERO_PAGE > > Will be a lot clearer. Sounds much better :) > > > + def_bool y> + depends on HUGETLB_PAGE && > ARCH_WANTS_HUGE_ZERO_PAGE_ALWAYS > > I suspect it should then also be independent of HUGETLB_PAGE? You are right. So we don't depend on any of these features. > > > + help > > + Typically huge_zero_folio, which is a huge page of zeroes, is allocated > > + on demand and deallocated when not in use. This option will always > > + allocate huge_zero_folio for zeroing and it is never deallocated. > > + Not suitable for memory constrained systems. > > I assume that code then has to live in mm/memory.c ? Hmm, then huge_zero_folio should have always been in mm/memory.c to begin with? I assume probably this was placed in mm/huge_memory.c because the users of this huge_zero_folio has been a part of mm/huge_memory.c? So IIUC your comment, we should move the huge_zero_page_init() in the first patch to mm/memory.c and the existing shrinker code can be a part where they already are? -- Pankaj