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Thu, 01 Oct 2026 08:33:57 -0700 (PDT) From: Qiliang Yuan Subject: [PATCH 0/2] mm/compaction: stop repeating failed async compaction on every THP fault Date: Thu, 01 Oct 2026 23:33:47 +0800 Message-Id: <20261001-bug-mm-thp-async-compact-defer-v1-0-0174c7923430@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-B4-Tracking: v=1; b=H4sIAFt9vmoC/x3NSQqEMBBA0atIrS3IgNL0VcRFhorWIjEkKjbi3 Tu4fJv/b6hUmCp8uxsKnVx5Sw2y78CtJi2E7JtBCTVKISTaY8EYcV8zmvpLDt0Ws3E7egpU0H6 0HqQNVg0eWiQXCny9g2l+nj92WGescAAAAA== To: Andrew Morton , Kairui Song , Qi Zheng , Shakeel Butt , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Baoquan He , Baolin Wang , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , Brendan Jackman , Johannes Weiner , Zi Yan Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, Qiliang Yuan X-Mailer: b4 0.13.0 A THP fault on a MADV_HUGEPAGE VMA tries the local node first with a single round of async direct compaction. A failed async run is never deferred, so when the local node is fragmented by memory that can't be migrated, such as long-term RDMA pins, every 2M fault scans the zone again before falling back to another node. Patch 1 splits the deferral state by migration mode. Patch 2 defers async compaction on its own state after it fails, leaving sync compaction as it is. Populating a 4 GiB MADV_HUGEPAGE buffer on a node fragmented by pinned memory, direct compactions drop from 735 to 15 and the time spent in compaction from 122.7 ms to 3.6 ms. Fewer of the THPs are allocated on the local node, 1126 instead of 1313; the rest come from the other node. Details and the movable-memory case are in patch 2. Signed-off-by: Qiliang Yuan --- Qiliang Yuan (2): mm/compaction: keep compaction deferral state per migration mode mm/compaction: defer failed async direct compaction include/linux/mmzone.h | 7 ++-- include/trace/events/compaction.h | 27 ++++++++------ mm/compaction.c | 77 ++++++++++++++++++++++----------------- 3 files changed, 63 insertions(+), 48 deletions(-) --- base-commit: 551c722f40809618230001baccf219193e22fc5a change-id: 20261001-bug-mm-thp-async-compact-defer-b83351bfb25d Best regards, -- Qiliang Yuan