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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 References: <20260418024429.4055056-1-ziy@nvidia.com> <20260418024429.4055056-3-ziy@nvidia.com> From: Baolin Wang In-Reply-To: <20260418024429.4055056-3-ziy@nvidia.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 01FA9140012 X-Stat-Signature: bb5qpjd3mbsup7q5ix6jy51giyoi8wyi X-Rspam-User: X-HE-Tag: 1776666529-228036 X-HE-Meta: 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 rhSz5xYW zVGhLGuznmUatJIjfnDJQzbJ1ogNH6xVAgAdAIzZtrINXLlShjUdzyogRGQfV9fTSMX2KfTD9LlSUznbEUJmiPA2hH4dNs/yROJ9xsBQdHkVQm8PgMByiAuUZTBdgALNP5x4xU0K4TZ5Rz+hxABHn4R9n79Dhfa5trGylhlkENXNwURpoWl9k/OpuUYZJAHTUAgLc1MzVxlwIlckM/SBScavMssCKbN771fwE8ORPQkH0R2y1RNMLUZXDH2XmP4j0Tf4+bD+N5xtylTbtYFnqeImE8Gq29Fux9FSPszv3fNka/as9dVdXJAcHb+bGwaN8oZ9B+bbSUSB+VtksOejVFkJUg73ls7VFNNtW9CruexhGk3v/2rlzxoixbg== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 4/18/26 10:44 AM, Zi Yan wrote: > This check ensures the correctness of collapse read-only THPs for FSes > after READ_ONLY_THP_FOR_FS is enabled by default for all FSes supporting > PMD THP pagecache. > > READ_ONLY_THP_FOR_FS only supports read-only fd and uses mapping->nr_thps > and inode->i_writecount to prevent any write to read-only to-be-collapsed > folios. In upcoming commits, READ_ONLY_THP_FOR_FS will be removed and the > aforementioned mechanism will go away too. To ensure khugepaged functions > as expected after the changes, skip if any folio is dirty after > try_to_unmap(), since a dirty folio means this read-only folio > got some writes via mmap can happen between try_to_unmap() and > try_to_unmap_flush() via cached TLB entries and khugepaged does not support > writable pagecache folio collapse yet. > > Signed-off-by: Zi Yan > --- LGTM. Reviewed-by: Baolin Wang