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Mon, 09 Nov 2026 01:08:58 -0800 (PST) Received: from intel.company.local ([122.11.210.25]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3b12790befasm6031438a91.13.2026.11.09.01.08.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 09 Nov 2026 01:08:56 -0800 (PST) From: Wandun Chen To: david@kernel.org, hughd@google.com, akpm@linux-foundation.org, fengwei.yin@intel.com Cc: ziy@nvidia.com, matthew.brost@intel.com, joshua.hahnjy@gmail.com, byungchul@sk.com, gourry@gourry.net, ying.huang@linux.alibaba.com, apopple@nvidia.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH] mm/migrate: fix mlock state loss when migrating PTE-mapped large folios Date: Mon, 9 Nov 2026 17:08:46 +0800 Message-ID: <20261109090846.1068409-1-chenwandun1@gmail.com> X-Mailer: git-send-email 2.43.0 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Wandun Chen try_to_migrate() clears PG_mlocked when unmapping the source folio. For PTE-mapped large folios, remove_migration_pte() restores one PTE at a time, but the rmap helpers only restore mlock for full-folio mappings. This leaves the destination PTE-mapped large folio without PG_mlocked. Restore mlock once all PTEs of the destination folio are restored under a single page table lock. Fixes: dc68badcede4 ("mm: mlock: update mlock_pte_range to handle large folio") Signed-off-by: Wandun Chen --- mm/migrate.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/mm/migrate.c b/mm/migrate.c index 94033c222e04..140e291d4587 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -353,6 +353,7 @@ static bool remove_migration_pte(struct folio *folio, { struct rmap_walk_arg *rmap_walk_arg = arg; DEFINE_FOLIO_VMA_WALK(pvmw, rmap_walk_arg->folio, vma, addr, PVMW_SYNC | PVMW_MIGRATION); + unsigned long nr_ptes = 0; while (page_vma_mapped_walk(&pvmw)) { rmap_t rmap_flags = RMAP_NONE; @@ -446,9 +447,16 @@ static bool remove_migration_pte(struct folio *folio, else folio_add_file_rmap_pte(folio, new, vma); set_pte_at(vma->vm_mm, pvmw.address, pvmw.pte, pte); + + nr_ptes++; } - if (READ_ONCE(vma->vm_flags) & VM_LOCKED) + if (READ_ONCE(vma->vm_flags) & VM_LOCKED) { + if (folio_test_large(folio) && + nr_ptes == folio_nr_pages(folio) && + !(pvmw.flags & PVMW_PGTABLE_CROSSED)) + mlock_vma_folio(folio, vma); mlock_drain_local(); + } trace_remove_migration_pte(pvmw.address, pte_val(pte), compound_order(new)); -- 2.43.0