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Message-ID: <282c5f993e61ca57a764a84d0abb96e355dee852.1761288179.git.lorenzo.stoakes@oracle.com>
Date: Fri, 24 Oct 2025 08:41:25 +0100
From: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Christian Borntraeger <borntraeger@...ux.ibm.com>,
Janosch Frank <frankja@...ux.ibm.com>,
Claudio Imbrenda <imbrenda@...ux.ibm.com>,
David Hildenbrand <david@...hat.com>,
Alexander Gordeev <agordeev@...ux.ibm.com>,
Gerald Schaefer <gerald.schaefer@...ux.ibm.com>,
Heiko Carstens <hca@...ux.ibm.com>, Vasily Gorbik <gor@...ux.ibm.com>,
Sven Schnelle <svens@...ux.ibm.com>, Zi Yan <ziy@...dia.com>,
Baolin Wang <baolin.wang@...ux.alibaba.com>,
"Liam R . Howlett" <Liam.Howlett@...cle.com>,
Nico Pache <npache@...hat.com>, Ryan Roberts <ryan.roberts@....com>,
Dev Jain <dev.jain@....com>, Barry Song <baohua@...nel.org>,
Lance Yang <lance.yang@...ux.dev>,
Kemeng Shi <shikemeng@...weicloud.com>,
Kairui Song <kasong@...cent.com>, Nhat Pham <nphamcs@...il.com>,
Baoquan He <bhe@...hat.com>, Chris Li <chrisl@...nel.org>,
Peter Xu <peterx@...hat.com>, Matthew Wilcox <willy@...radead.org>,
Jason Gunthorpe <jgg@...pe.ca>, Leon Romanovsky <leon@...nel.org>,
Muchun Song <muchun.song@...ux.dev>,
Oscar Salvador <osalvador@...e.de>, Vlastimil Babka <vbabka@...e.cz>,
Mike Rapoport <rppt@...nel.org>,
Suren Baghdasaryan <surenb@...gle.com>, Michal Hocko <mhocko@...e.com>,
Jann Horn <jannh@...gle.com>, Matthew Brost <matthew.brost@...el.com>,
Joshua Hahn <joshua.hahnjy@...il.com>, Rakie Kim <rakie.kim@...com>,
Byungchul Park <byungchul@...com>, Gregory Price <gourry@...rry.net>,
Ying Huang <ying.huang@...ux.alibaba.com>,
Alistair Popple <apopple@...dia.com>, Pedro Falcato <pfalcato@...e.de>,
Pasha Tatashin <pasha.tatashin@...een.com>,
Rik van Riel <riel@...riel.com>, Harry Yoo <harry.yoo@...cle.com>,
kvm@...r.kernel.org, linux-s390@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
linux-mm@...ck.org
Subject: [RFC PATCH 09/12] 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().
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
---
mm/huge_memory.c | 72 ++++++++++++++++++++++++++----------------------
1 file changed, 39 insertions(+), 33 deletions(-)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 755d38f82aec..fa928ca42b6d 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2498,6 +2498,42 @@ bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,
return false;
}
+static void change_non_present_huge_pmd(struct mm_struct *mm,
+ unsigned long addr, pmd_t *pmd, bool uffd_wp,
+ bool uffd_wp_resolve)
+{
+ swp_entry_t entry = pmd_to_swp_entry(*pmd);
+ struct folio *folio = pfn_swap_entry_folio(entry);
+ pmd_t newpmd;
+
+ VM_WARN_ON(!is_pmd_non_present_folio_entry(*pmd));
+ if (is_writable_migration_entry(entry)) {
+ /*
+ * A protection check is difficult so
+ * just be safe and disable write
+ */
+ if (folio_test_anon(folio))
+ entry = make_readable_exclusive_migration_entry(swp_offset(entry));
+ else
+ entry = make_readable_migration_entry(swp_offset(entry));
+ newpmd = swp_entry_to_pmd(entry);
+ if (pmd_swp_soft_dirty(*pmd))
+ newpmd = pmd_swp_mksoft_dirty(newpmd);
+ } else if (is_writable_device_private_entry(entry)) {
+ entry = make_readable_device_private_entry(swp_offset(entry));
+ newpmd = swp_entry_to_pmd(entry);
+ } else {
+ newpmd = *pmd;
+ }
+
+ if (uffd_wp)
+ newpmd = pmd_swp_mkuffd_wp(newpmd);
+ else if (uffd_wp_resolve)
+ 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
@@ -2526,41 +2562,11 @@ int change_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *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;
-
- VM_WARN_ON(!is_pmd_non_present_folio_entry(*pmd));
- if (is_writable_migration_entry(entry)) {
- /*
- * A protection check is difficult so
- * just be safe and disable write
- */
- if (folio_test_anon(folio))
- entry = make_readable_exclusive_migration_entry(swp_offset(entry));
- else
- entry = make_readable_migration_entry(swp_offset(entry));
- newpmd = swp_entry_to_pmd(entry);
- if (pmd_swp_soft_dirty(*pmd))
- newpmd = pmd_swp_mksoft_dirty(newpmd);
- } else if (is_writable_device_private_entry(entry)) {
- entry = make_readable_device_private_entry(swp_offset(entry));
- newpmd = swp_entry_to_pmd(entry);
- } else {
- newpmd = *pmd;
- }
-
- if (uffd_wp)
- newpmd = pmd_swp_mkuffd_wp(newpmd);
- else if (uffd_wp_resolve)
- newpmd = pmd_swp_clear_uffd_wp(newpmd);
- if (!pmd_same(*pmd, newpmd))
- set_pmd_at(mm, addr, pmd, newpmd);
+ 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) {
int target_node = NUMA_NO_NODE;
--
2.51.0
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