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Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Shuah Khan , linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH 7.2 v2 05/12] mm/khugepaged: remove READ_ONLY_THP_FOR_FS check in hugepage_pmd_enabled() Message-ID: References: <20260413192030.3275825-1-ziy@nvidia.com> <20260413192030.3275825-6-ziy@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260413192030.3275825-6-ziy@nvidia.com> X-Rspamd-Queue-Id: 5110DA0011 X-Stat-Signature: rjx3go1x7w8efc8anhfg3dd65hnioafj X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1776112446-504288 X-HE-Meta: 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 qRl/Zlox cfun3Fpf6fA80AeYT1XaXCbksyjkdES8mo7eWVSXmpbh2DD41m/1fVhGlESCThOM86yUjsypNcn8Afo9WErjRYZT+hTmkS6CCnxBdxTjujfVvuciGp3pI4Bi/jO63M6T9dn0ZP6yko/eyNnJcGfUOOlLkRmVLkhtGw9DE0tDqiqParQlagVpX6I57sbwtWmt/lwDUQ50d6PrFdT6ha182Vhc8GP4xpNdlms8ieRVUZIE452vQ7qbZ+QpNomHBlm4VV6gFZH2EAWJzAPZEU+fMeqrxszAfdfjyMKy5E2NMXwfnrRg= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Apr 13, 2026 at 03:20:23PM -0400, Zi Yan wrote: > After READ_ONLY_THP_FOR_FS Kconfig is removed, this check becomes dead > code. > > This changes hugepage_pmd_enabled() semantics. Previously, with > READ_ONLY_THP_FOR_FS enabled, hugepage_pmd_enabled() returned true whenever > /sys/kernel/mm/transparent_hugepage/enabled was set to "always" or > "madvise". > > After this change, hugepage_pmd_enabled() is governed only by the anon and > shmem PMD THP controls. As a result, khugepaged collapse for file-backed > folios no longer runs unconditionally under the top-level THP setting, and > now depends on the anon/shmem PMD configuration. This seems like it'll turn off khugepaged too easily. I would have thought we'd want: - if (IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && - hugepage_global_enabled()) + if (hugepage_global_enabled()) return true; ... or maybe this whole thing could be simplified?