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>

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 3bf8d2bf937459fa874bc6df6fafaceed8ff7b8f..0fdb3be39e31a8f98ae88fd93398868947fbcf1f 100644 (file)
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2424,6 +2424,42 @@ 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
@@ -2452,41 +2488,11 @@ 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) {