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| author | Hugh Dickins <hughd@google.com> | 2022-11-22 01:51:50 -0800 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2022-11-30 15:58:48 -0800 |
| commit | 96d82deb743ab42c8f0b911eb49db83f0e6db311 (patch) | |
| tree | 237c2590963ac1875521bbc3004eb845e2e64375 | |
| parent | 4b51634cd16a01b2be0f6b69cc0dae63de4751f2 (diff) | |
| download | linux-96d82deb743ab42c8f0b911eb49db83f0e6db311.tar.bz2 | |
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>
| -rw-r--r-- | mm/huge_memory.c | 15 |
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, |