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authorHugh Dickins <hughd@google.com>2022-11-22 12:51:50 +0300
committerAndrew Morton <akpm@linux-foundation.org>2022-12-01 02:58:48 +0300
commit96d82deb743ab42c8f0b911eb49db83f0e6db311 (patch)
tree237c2590963ac1875521bbc3004eb845e2e64375 /mm/huge_memory.c
parent4b51634cd16a01b2be0f6b69cc0dae63de4751f2 (diff)
downloadlinux-96d82deb743ab42c8f0b911eb49db83f0e6db311.tar.xz
mm,thp,rmap: clean up the end of __split_huge_pmd_locked()
It's hard to add a page_add_anon_rmap() into __split_huge_pmd_locked()'s HPAGE_PMD_NR set_pte_at() loop, without wincing at the "freeze" case's HPAGE_PMD_NR page_remove_rmap() loop below it. It's just a mistake to add rmaps in the "freeze" (insert migration entries prior to splitting huge page) case: the pmd_migration case already avoids doing that, so just follow its lead. page_add_ref() versus put_page() likewise. But why is one more put_page() needed in the "freeze" case? Because it's removing the pmd rmap, already removed when pmd_migration (and freeze and pmd_migration are mutually exclusive cases). Link: https://lkml.kernel.org/r/d43748aa-fece-e0b9-c4ab-f23c9ebc9011@google.com Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Dan Carpenter <error27@gmail.com> Cc: David Hildenbrand <david@redhat.com> Cc: James Houghton <jthoughton@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: Peter Xu <peterx@redhat.com> Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Yang Shi <shy828301@gmail.com> Cc: Yu Zhao <yuzhao@google.com> Cc: Zach O'Keefe <zokeefe@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/huge_memory.c')
-rw-r--r--mm/huge_memory.c15
1 files changed, 5 insertions, 10 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 681253adf529..aba340684285 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2141,7 +2141,6 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
uffd_wp = pmd_uffd_wp(old_pmd);
VM_BUG_ON_PAGE(!page_count(page), page);
- page_ref_add(page, HPAGE_PMD_NR - 1);
/*
* Without "freeze", we'll simply split the PMD, propagating the
@@ -2161,6 +2160,8 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
anon_exclusive = PageAnon(page) && PageAnonExclusive(page);
if (freeze && anon_exclusive && page_try_share_anon_rmap(page))
freeze = false;
+ if (!freeze)
+ page_ref_add(page, HPAGE_PMD_NR - 1);
}
/*
@@ -2216,27 +2217,21 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
entry = pte_mksoft_dirty(entry);
if (uffd_wp)
entry = pte_mkuffd_wp(entry);
+ page_add_anon_rmap(page + i, vma, addr, false);
}
pte = pte_offset_map(&_pmd, addr);
BUG_ON(!pte_none(*pte));
set_pte_at(mm, addr, pte, entry);
- if (!pmd_migration)
- page_add_anon_rmap(page + i, vma, addr, false);
pte_unmap(pte);
}
if (!pmd_migration)
page_remove_rmap(page, vma, true);
+ if (freeze)
+ put_page(page);
smp_wmb(); /* make pte visible before pmd */
pmd_populate(mm, pmd, pgtable);
-
- if (freeze) {
- for (i = 0; i < HPAGE_PMD_NR; i++) {
- page_remove_rmap(page + i, vma, false);
- put_page(page + i);
- }
- }
}
void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,