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b=I1JeGroo5hMIqTqxRa9QFMgft/zZ2PWbwIK+GJHof+NucF9RGKXu06QCYnxZ1izgD VbwCrk+dYOlxJQLJ7HhTThd5XmYRA9pg6KNyqX7+95qIhlwTJJ8M86rc2IxOuqjTMS KzKMutpZYR7A+bH/IliIGo1NS7jSKG/R+lOCJQA/gk64/YG7XBFSmThGeTBsoBBVJ/ 9rg3ENyOIFI7CMS5xIou2ziewdT8gGkHb1w7VE0BSiMN17MSCaOw4q4oskKNy5vw+o 0kAj6gGT8+ghznlOpAUxMyAe2wE7zZmz+lvg99mMqQSGEnsqW9sIhedMARplbaKD1i O8nkVwtBTCcUg== Message-ID: Date: Wed, 1 Apr 2026 16:38:21 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 05/10] mm/huge_memory: remove READ_ONLY_THP_FOR_FS from file_thp_enabled() To: Matthew Wilcox , WANG Rui Cc: ziy@nvidia.com, ljs@kernel.org, Liam.Howlett@oracle.com, akpm@linux-foundation.org, baohua@kernel.org, baolin.wang@linux.alibaba.com, brauner@kernel.org, clm@fb.com, dev.jain@arm.com, dsterba@suse.com, jack@suse.cz, lance.yang@linux.dev, linux-btrfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, mhocko@suse.com, npache@redhat.com, rppt@kernel.org, ryan.roberts@arm.com, shuah@kernel.org, songliubraving@fb.com, surenb@google.com, vbabka@kernel.org, viro@zeniv.linux.org.uk References: <20260330160942.173324-1-r@hev.cc> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Queue-Id: 6D29C40012 X-Stat-Signature: bwfzm691ijdtp5ii1xgquwnrtfdrdsbj X-Rspamd-Server: rspam06 X-HE-Tag: 1775054311-789072 X-HE-Meta: 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 jkCkrNN/ Czl8MuVX+4RMLNcdTnUveY6R8SadL00L1/9aunTY2AQJ4iptMkODf8dM1NWMOB+zBoSjgBDIx5W1HcU5l8qxsT96VA5rgjp+6N4Bu2dQMz8YuxPktYQA7XBXZcCN+CcE53Ujvem0/V0ZPj3UwDBt31QefAHDmGhw032PMYZRhwxbUPW+EvHkG3iJXxevI4n+t0N2G/bH/aEkC+E/0sLFay8BETpajLfgPi/BdPZCP7lGDkdD+PAwRm3K4PsSBRLwXASTYt9RKP5+O/g6R7P40+7M4K+dMvIfNIhoDjLwiOvb3bbI8ZYaqY9Xdfw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 3/30/26 18:19, Matthew Wilcox wrote: > On Tue, Mar 31, 2026 at 12:09:42AM +0800, WANG Rui wrote: >> Given the diversity of filesystems in use, each one requires dedicated >> engineering effort to implement and validate large folio support, and >> that assumes both sufficient resources and prioritization on the >> filesystem side. Even after support lands, coverage across different >> base page sizes and configurations may take additional time to mature. >> >> What I am really concerned about is the transition period: if filesystem >> support is not yet broadly ready, while we have already removed the >> fallback path, we may end up in a situation where PMD-sized mappings >> become effectively unavailable on many systems for some time. >> >> This is not about the long-term direction, but about the timing and >> practical readiness. > > If we leave this fallback in place, we'll never get filesystems to move > forward. It's time to rip off this bandaid; they've got eight months > before the next stable kernel. I guess if we don't force them to work on it I guess this will never happen. They shouldn't be holding our THP hacks we want to remove hostage. -- Cheers, David