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[173.79.60.52]) by smtp.gmail.com with ESMTPSA id af79cd13be357-930b545e47bsm957792285a.35.2026.07.20.12.35.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 20 Jul 2026 12:35:59 -0700 (PDT) From: Gregory Price To: linux-mm@kvack.org Cc: Zhigang.Luo@amd.com, arun.george@samsung.com, balbirs@nvidia.com, brendan.jackman@linux.dev, yuzenghui@huawei.com, apopple@nvidia.com, alucerop@amd.com, matthew.brost@intel.com, akpm@linux-foundation.org, david@kernel.org, ljs@kernel.org, liam@infradead.org, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, corbet@lwn.net, skhan@linuxfoundation.org, gregkh@linuxfoundation.org, rafael@kernel.org, dakr@kernel.org, djbw@kernel.org, vishal.l.verma@intel.com, dave.jiang@intel.com, alison.schofield@intel.com, osandov@osandov.com, jannh@google.com, pfalcato@suse.de, jackmanb@google.com, hannes@cmpxchg.org, ziy@nvidia.com, pbonzini@redhat.com, osalvador@suse.de, joshua.hahnjy@gmail.com, rakie.kim@sk.com, byungchul@sk.com, gourry@gourry.net, ying.huang@linux.alibaba.com, kasong@tencent.com, qi.zheng@linux.dev, shakeel.butt@linux.dev, baohua@kernel.org, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, yury.norov@gmail.com, linux@rasmusvillemoes.dk, longman@redhat.com, ridong.chen@linux.dev, tj@kernel.org, mkoutny@suse.com, sj@kernel.org, jgg@ziepe.ca, jhubbard@nvidia.com, peterx@redhat.com, baolin.wang@linux.alibaba.com, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, lance.yang@linux.dev, usama.arif@linux.dev, xu.xin16@zte.com.cn, chengming.zhou@linux.dev, roman.gushchin@linux.dev, muchun.song@linux.dev, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, driver-core@lists.linux.dev, nvdimm@lists.linux.dev, linux-cxl@vger.kernel.org, linux-debuggers@vger.kernel.org, linux-fsdevel@vger.kernel.org, kvm@vger.kernel.org, cgroups@vger.kernel.org, damon@lists.linux.dev, linux-kselftest@vger.kernel.org, kernel-team@meta.com Subject: [PATCH v5 31/36] mm: add NODE_PRIVATE_CAP_LTPIN for private node folio pinning Date: Mon, 20 Jul 2026 15:34:25 -0400 Message-ID: <20260720193431.3841992-32-gourry@gourry.net> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260720193431.3841992-1-gourry@gourry.net> References: <20260720193431.3841992-1-gourry@gourry.net> Precedence: bulk X-Mailing-List: linux-debuggers@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Add NODE_PRIVATE_CAP_LTPIN so a node can opt back into gup pins. An opted-in node is then pinned exactly like ordinary memory, or migrated and pinned if in ZONE_MOVABLE. Signed-off-by: Gregory Price --- include/linux/node_private.h | 29 +++++++++++++++++++++++++++++ mm/gup.c | 3 ++- mm/internal.h | 9 +++++---- 3 files changed, 36 insertions(+), 5 deletions(-) diff --git a/include/linux/node_private.h b/include/linux/node_private.h index 5c3e070ed0deb..6f568bc0d46c7 100644 --- a/include/linux/node_private.h +++ b/include/linux/node_private.h @@ -17,6 +17,7 @@ struct page; #define NODE_PRIVATE_CAP_HOTUNPLUG (1UL << 2) /* allow hot-unplug */ #define NODE_PRIVATE_CAP_DEMOTION (1UL << 3) /* allow tiering demotion */ #define NODE_PRIVATE_CAP_NUMA_BALANCING (1UL << 4) /* allow NUMA balancing */ +#define NODE_PRIVATE_CAP_LTPIN (1UL << 5) /* allow GUP pins */ /** * struct node_private - Per-node container for N_MEMORY_PRIVATE nodes @@ -167,6 +168,29 @@ static inline bool node_allows_numa_balancing(int nid) return ret; } +/** + * node_allows_ltpin - may a folio on this node be long-term GUP-pinned? + * @nid: the node to test + * + * Opted-out private nodes cause longterm pins to outright fail regardless + * of ZONE placement (NORMAL would allow, MOVABLE would migrate first). + * + * Opted-in private nodes allow longterm pins to operate normally. + */ +static inline bool node_allows_ltpin(int nid) +{ + struct node_private *np; + bool ret; + + if (!node_state(nid, N_MEMORY_PRIVATE)) + return true; + rcu_read_lock(); + np = rcu_dereference(NODE_DATA(nid)->node_private); + ret = np && (np->caps & NODE_PRIVATE_CAP_LTPIN); + rcu_read_unlock(); + return ret; +} + #else /* !CONFIG_NUMA */ static inline bool folio_is_private_node(struct folio *folio) @@ -209,6 +233,11 @@ static inline bool node_allows_numa_balancing(int nid) return true; } +static inline bool node_allows_ltpin(int nid) +{ + return true; +} + #endif /* CONFIG_NUMA */ #if defined(CONFIG_NUMA) && defined(CONFIG_MEMORY_HOTPLUG) diff --git a/mm/gup.c b/mm/gup.c index a7d4de223785c..1e313aa590bc1 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -547,7 +547,8 @@ static struct folio *try_grab_folio_fast(struct page *page, int refs, /* * Can't do FOLL_LONGTERM + FOLL_PIN gup fast path if not in a * right zone, so fail and let the caller fall back to the slow - * path. Fail for private-node folios here so slow path rejects. + * path. Fail for non-opted-in private node folios here so the + * slow path can reject the pin entirely. */ if (unlikely((flags & FOLL_LONGTERM) && !folio_allows_longterm_pin(folio))) { diff --git a/mm/internal.h b/mm/internal.h index 01ab8b32b0bd8..9621eb127c28c 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -146,19 +146,20 @@ static inline bool folio_allows_numa_balance(struct folio *folio) static inline bool folio_allows_longterm_pin(struct folio *folio) { return folio_is_longterm_pinnable(folio) && - !folio_is_private_node(folio); + node_allows_ltpin(folio_nid(folio)); } /* * folio_longterm_pin_forbidden() - must a longterm pin of this folio fail * outright (neither pinned in place nor migrated off the node)? * - * True for any folio on a private node: such memory can be neither pinned - * nor migrated, so the pin must be rejected with the folio left in place. + * True only for a folio on a private node that did not opt into longterm + * pinning (NODE_PRIVATE_CAP_LTPIN); node_allows_ltpin() is true for ordinary + * nodes and for opted-in private nodes, so this never trips them. */ static inline bool folio_longterm_pin_forbidden(struct folio *folio) { - return folio_is_private_node(folio); + return !node_allows_ltpin(folio_nid(folio)); } /* -- 2.53.0-Meta