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Tue, 09 Sep 2025 19:45:33 -0700 (PDT) From: Yafang Shao To: akpm@linux-foundation.org, david@redhat.com, ziy@nvidia.com, baolin.wang@linux.alibaba.com, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, hannes@cmpxchg.org, usamaarif642@gmail.com, gutierrez.asier@huawei-partners.com, willy@infradead.org, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, ameryhung@gmail.com, rientjes@google.com, corbet@lwn.net, 21cnbao@gmail.com, shakeel.butt@linux.dev Cc: bpf@vger.kernel.org, linux-mm@kvack.org, linux-doc@vger.kernel.org, Yafang Shao Subject: [PATCH v7 mm-new 03/10] mm: thp: decouple THP allocation between swap and page fault paths Date: Wed, 10 Sep 2025 10:44:40 +0800 Message-Id: <20250910024447.64788-4-laoar.shao@gmail.com> X-Mailer: git-send-email 2.37.1 (Apple Git-137.1) In-Reply-To: <20250910024447.64788-1-laoar.shao@gmail.com> References: <20250910024447.64788-1-laoar.shao@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 635FD180007 X-Stat-Signature: efo87i4jhrom6xwsqjjx8x5n71zgucep X-HE-Tag: 1757472335-722607 X-HE-Meta: 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 mrYVLziO 0UvzFeEVrPovb+7lgKExd9bMdnd0yw8Pl1V1aXlvKKI32GDBdai8//CupbRs4kYlDRZVeotGpnUhGopsLlyY9ZY2/DCWj46jXDLWDYoNdWfp/Bz2imTXMUxPOfjaHuC7rTFFJpcGpPCBLS5JX6C0WsCyDmh0umNjuO2qjRViV580HzfVU1FmM61QBlSALeO9OoXwLF8P/hf0RlPlzO5qbwgfUHWoQ8F0UO6fDC0j3SimfztnMfY0wx64Fg4mKoR/aVNpa+Vy1vR4QzHii6PVEDWlhq6YHIOHmPz94pW2fOWYyP3liMuIaAC3SZtY8PPcXhilFxzRV7XLxwjWeSznEebEpUGmGekpA68JCVG62PxP/nmYamfgnSONGVAVz2m5LviXlr9OsthAoUjd/0l58AfCRg7uSXnfGlVLzbOXaB13jdOBxz3FS7y11BLzlTE9khYwiqadj+NHV7+saPYHZoTCYLz7ZBayp3ZHuC/9HFIbMKkd7BYTfjmtEIBapX/5+JnsulQPQooCUCJVVeghSu1VamblSqL184oDRxHXkHD9rKnKOwvCw55KEwIr55xLaef3a3zxqrtmEn1k= 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: The new BPF capability enables finer-grained THP policy decisions by introducing separate handling for swap faults versus normal page faults. As highlighted by Barry: We’ve observed that swapping in large folios can lead to more swap thrashing for some workloads- e.g. kernel build. Consequently, some workloads might prefer swapping in smaller folios than those allocated by alloc_anon_folio(). While prtcl() could potentially be extended to leverage this new policy, doing so would require modifications to the uAPI. Signed-off-by: Yafang Shao Cc: Barry Song <21cnbao@gmail.com> --- include/linux/huge_mm.h | 3 ++- mm/huge_memory.c | 2 +- mm/memory.c | 2 +- 3 files changed, 4 insertions(+), 3 deletions(-) diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h index f72a5fd04e4f..b9742453806f 100644 --- a/include/linux/huge_mm.h +++ b/include/linux/huge_mm.h @@ -97,9 +97,10 @@ extern struct kobj_attribute thpsize_shmem_enabled_attr; enum tva_type { TVA_SMAPS, /* Exposing "THPeligible:" in smaps. */ - TVA_PAGEFAULT, /* Serving a page fault. */ + TVA_PAGEFAULT, /* Serving a non-swap page fault. */ TVA_KHUGEPAGED, /* Khugepaged collapse. */ TVA_FORCED_COLLAPSE, /* Forced collapse (e.g. MADV_COLLAPSE). */ + TVA_SWAP, /* Serving a swap */ }; #define thp_vma_allowable_order(vma, vm_flags, type, order) \ diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 26cedfcd7418..523153d21a41 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -103,7 +103,7 @@ unsigned long __thp_vma_allowable_orders(struct vm_area_struct *vma, unsigned long orders) { const bool smaps = type == TVA_SMAPS; - const bool in_pf = type == TVA_PAGEFAULT; + const bool in_pf = (type == TVA_PAGEFAULT || type == TVA_SWAP); const bool forced_collapse = type == TVA_FORCED_COLLAPSE; unsigned long supported_orders; diff --git a/mm/memory.c b/mm/memory.c index d9de6c056179..d8819cac7930 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -4515,7 +4515,7 @@ static struct folio *alloc_swap_folio(struct vm_fault *vmf) * Get a list of all the (large) orders below PMD_ORDER that are enabled * and suitable for swapping THP. */ - orders = thp_vma_allowable_orders(vma, vma->vm_flags, TVA_PAGEFAULT, + orders = thp_vma_allowable_orders(vma, vma->vm_flags, TVA_SWAP, BIT(PMD_ORDER) - 1); orders = thp_vma_suitable_orders(vma, vmf->address, orders); orders = thp_swap_suitable_orders(swp_offset(entry), -- 2.47.3