Commit 5dfa7916 authored Nov 10, 2025 by Lorenzo Stoakes Committed by Andrew Morton Nov 24, 2025

mm/huge_memory: refactor change_huge_pmd() non-present logic

Similar to copy_huge_pmd(), there is a large mass of open-coded logic for
the CONFIG_ARCH_ENABLE_THP_MIGRATION non-present entry case that does not
use thp_migration_supported() consistently.

Resolve this by separating out this logic and introduce
change_non_present_huge_pmd().

No functional change intended.

Link: https://lkml.kernel.org/r/451b85636ad711e307fdfbff19af699fdab4d05f.1762812360.git.lorenzo.stoakes@oracle.com


Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Chris Li <chrisl@kernel.org>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Gregory Price <gourry@gourry.net>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Janosch Frank <frankja@linux.ibm.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Kairui Song <kasong@tencent.com>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Mathew Brost <matthew.brost@intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Nico Pache <npache@redhat.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Wei Xu <weixugc@google.com>
Cc: xu xin <xu.xin16@zte.com.cn>
Cc: Yuanchu Xie <yuanchu@google.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

parent e244d82d

mm/huge_memory.c

+39 −33

Original line number	Diff line number	Diff line
		@@ -2424,36 +2424,10 @@ bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,
		return false;
		}

		/*
		* Returns
		* - 0 if PMD could not be locked
		* - 1 if PMD was locked but protections unchanged and TLB flush unnecessary
		* or if prot_numa but THP migration is not supported
		* - HPAGE_PMD_NR if protections changed and TLB flush necessary
		*/
		int change_huge_pmd(struct mmu_gather tlb, struct vm_area_struct vma,
		pmd_t *pmd, unsigned long addr, pgprot_t newprot,
		unsigned long cp_flags)
		static void change_non_present_huge_pmd(struct mm_struct *mm,
		unsigned long addr, pmd_t *pmd, bool uffd_wp,
		bool uffd_wp_resolve)
		{
		struct mm_struct *mm = vma->vm_mm;
		spinlock_t *ptl;
		pmd_t oldpmd, entry;
		bool prot_numa = cp_flags & MM_CP_PROT_NUMA;
		bool uffd_wp = cp_flags & MM_CP_UFFD_WP;
		bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE;
		int ret = 1;

		tlb_change_page_size(tlb, HPAGE_PMD_SIZE);

		if (prot_numa && !thp_migration_supported())
		return 1;

		ptl = __pmd_trans_huge_lock(pmd, vma);
		if (!ptl)
		return 0;

		#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
		if (is_swap_pmd(*pmd)) {
		swp_entry_t entry = pmd_to_swp_entry(*pmd);
		struct folio *folio = pfn_swap_entry_folio(entry);
		pmd_t newpmd;
		@@ -2484,9 +2458,41 @@ int change_huge_pmd(struct mmu_gather tlb, struct vm_area_struct vma,
		newpmd = pmd_swp_clear_uffd_wp(newpmd);
		if (!pmd_same(*pmd, newpmd))
		set_pmd_at(mm, addr, pmd, newpmd);
		}

		/*
		* Returns
		* - 0 if PMD could not be locked
		* - 1 if PMD was locked but protections unchanged and TLB flush unnecessary
		* or if prot_numa but THP migration is not supported
		* - HPAGE_PMD_NR if protections changed and TLB flush necessary
		*/
		int change_huge_pmd(struct mmu_gather tlb, struct vm_area_struct vma,
		pmd_t *pmd, unsigned long addr, pgprot_t newprot,
		unsigned long cp_flags)
		{
		struct mm_struct *mm = vma->vm_mm;
		spinlock_t *ptl;
		pmd_t oldpmd, entry;
		bool prot_numa = cp_flags & MM_CP_PROT_NUMA;
		bool uffd_wp = cp_flags & MM_CP_UFFD_WP;
		bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE;
		int ret = 1;

		tlb_change_page_size(tlb, HPAGE_PMD_SIZE);

		if (prot_numa && !thp_migration_supported())
		return 1;

		ptl = __pmd_trans_huge_lock(pmd, vma);
		if (!ptl)
		return 0;

		if (thp_migration_supported() && is_swap_pmd(*pmd)) {
		change_non_present_huge_pmd(mm, addr, pmd, uffd_wp,
		uffd_wp_resolve);
		goto unlock;
		}
		#endif

		if (prot_numa) {