Commit de4d6c94 authored Nov 10, 2025 by Lorenzo Stoakes Committed by Andrew Morton Nov 24, 2025

fs/proc/task_mmu: refactor pagemap_pmd_range()

Separate out THP logic so we can drop an indentation level and reduce the
amount of noise in this function.

We add pagemap_pmd_range_thp() for this purpose.

While we're here, convert the VM_BUG_ON() to a VM_WARN_ON_ONCE() at the
same time.

No functional change intended.

Link: https://lkml.kernel.org/r/f9ce7f3bb57e3627288225e23f2498cc5315f5ab.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 fb410d8b

fs/proc/task_mmu.c

+77 −69

Original line number	Diff line number	Diff line
		@@ -1985,23 +1985,17 @@ static pagemap_entry_t pte_to_pagemap_entry(struct pagemapread *pm,
		return make_pme(frame, flags);
		}

		static int pagemap_pmd_range(pmd_t *pmdp, unsigned long addr, unsigned long end,
		struct mm_walk *walk)
		{
		struct vm_area_struct *vma = walk->vma;
		struct pagemapread *pm = walk->private;
		spinlock_t *ptl;
		pte_t pte, orig_pte;
		int err = 0;
		#ifdef CONFIG_TRANSPARENT_HUGEPAGE

		ptl = pmd_trans_huge_lock(pmdp, vma);
		if (ptl) {
		static int pagemap_pmd_range_thp(pmd_t *pmdp, unsigned long addr,
		unsigned long end, struct vm_area_struct *vma,
		struct pagemapread *pm)
		{
		unsigned int idx = (addr & ~PMD_MASK) >> PAGE_SHIFT;
		u64 flags = 0, frame = 0;
		pmd_t pmd = *pmdp;
		struct page *page = NULL;
		struct folio *folio = NULL;
		int err = 0;

		if (vma->vm_flags & VM_SOFTDIRTY)
		flags \|= PM_SOFT_DIRTY;
		@@ -2016,9 +2010,7 @@ static int pagemap_pmd_range(pmd_t *pmdp, unsigned long addr, unsigned long end,
		flags \|= PM_UFFD_WP;
		if (pm->show_pfn)
		frame = pmd_pfn(pmd) + idx;
		}
		#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
		else if (is_swap_pmd(pmd)) {
		} else if (thp_migration_supported() && is_swap_pmd(pmd)) {
		swp_entry_t entry = pmd_to_swp_entry(pmd);
		unsigned long offset;

		@@ -2035,10 +2027,9 @@ static int pagemap_pmd_range(pmd_t *pmdp, unsigned long addr, unsigned long end,
		flags \|= PM_SOFT_DIRTY;
		if (pmd_swp_uffd_wp(pmd))
		flags \|= PM_UFFD_WP;
		VM_BUG_ON(!is_pmd_migration_entry(pmd));
		VM_WARN_ON_ONCE(!is_pmd_migration_entry(pmd));
		page = pfn_swap_entry_to_page(entry);
		}
		#endif

		if (page) {
		folio = page_folio(page);
		@@ -2065,11 +2056,28 @@ static int pagemap_pmd_range(pmd_t *pmdp, unsigned long addr, unsigned long end,
		frame += (1 << MAX_SWAPFILES_SHIFT);
		}
		}
		spin_unlock(ptl);
		return err;
		}
		#endif /* CONFIG_TRANSPARENT_HUGEPAGE */

		static int pagemap_pmd_range(pmd_t *pmdp, unsigned long addr, unsigned long end,
		struct mm_walk *walk)
		{
		struct vm_area_struct *vma = walk->vma;
		struct pagemapread *pm = walk->private;
		spinlock_t *ptl;
		pte_t pte, orig_pte;
		int err = 0;

		#ifdef CONFIG_TRANSPARENT_HUGEPAGE
		ptl = pmd_trans_huge_lock(pmdp, vma);
		if (ptl) {
		err = pagemap_pmd_range_thp(pmdp, addr, end, vma, pm);
		spin_unlock(ptl);
		return err;
		}
		#endif

		/*
		* We can assume that @vma always points to a valid one and @end never
		* goes beyond vma->vm_end.