From: David Hildenbrand david@redhat.com
mainline inclusion from mainline-v6.8-rc1 commit ebe2e35ec0f256372c158a18de459fb60070b313 category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I9CESE CVE: NA
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hugetlb rmap handling differs quite a lot from "ordinary" rmap code. For example, hugetlb currently only supports entire mappings, and treats any mapping as mapped using a single "logical PTE". Let's move it out of the way so we can overhaul our "ordinary" rmap. implementation/interface.
So let's introduce and use hugetlb_try_dup_anon_rmap() to make all hugetlb handling use dedicated hugetlb_* rmap functions.
Add sanity checks that we end up with the right folios in the right functions.
Note that is_device_private_page() does not apply to hugetlb.
Link: https://lkml.kernel.org/r/20231220224504.646757-5-david@redhat.com Signed-off-by: David Hildenbrand david@redhat.com Reviewed-by: Yin Fengwei fengwei.yin@intel.com Reviewed-by: Ryan Roberts ryan.roberts@arm.com Reviewed-by: Muchun Song songmuchun@bytedance.com Cc: Hugh Dickins hughd@google.com Cc: Matthew Wilcox (Oracle) willy@infradead.org Cc: Muchun Song muchun.song@linux.dev Cc: Peter Xu peterx@redhat.com Signed-off-by: Andrew Morton akpm@linux-foundation.org (cherry picked from commit ebe2e35ec0f256372c158a18de459fb60070b313) Signed-off-by: Kefeng Wang wangkefeng.wang@huawei.com --- include/linux/mm.h | 12 +++++++++--- include/linux/rmap.h | 18 ++++++++++++++++++ mm/hugetlb.c | 3 +-- 3 files changed, 28 insertions(+), 5 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h index ffa00d1cd17d..3f2fe3b85dc0 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1980,15 +1980,21 @@ static inline bool page_maybe_dma_pinned(struct page *page) * * The caller has to hold the PT lock and the vma->vm_mm->->write_protect_seq. */ -static inline bool page_needs_cow_for_dma(struct vm_area_struct *vma, - struct page *page) +static inline bool folio_needs_cow_for_dma(struct vm_area_struct *vma, + struct folio *folio) { VM_BUG_ON(!(raw_read_seqcount(&vma->vm_mm->write_protect_seq) & 1));
if (!test_bit(MMF_HAS_PINNED, &vma->vm_mm->flags)) return false;
- return page_maybe_dma_pinned(page); + return folio_maybe_dma_pinned(folio); +} + +static inline bool page_needs_cow_for_dma(struct vm_area_struct *vma, + struct page *page) +{ + return folio_needs_cow_for_dma(vma, page_folio(page)); }
/** diff --git a/include/linux/rmap.h b/include/linux/rmap.h index 74a5f4d3979f..9091895117e5 100644 --- a/include/linux/rmap.h +++ b/include/linux/rmap.h @@ -208,6 +208,22 @@ void hugetlb_add_anon_rmap(struct folio *, struct vm_area_struct *, void hugetlb_add_new_anon_rmap(struct folio *, struct vm_area_struct *, unsigned long address);
+/* See page_try_dup_anon_rmap() */ +static inline int hugetlb_try_dup_anon_rmap(struct folio *folio, + struct vm_area_struct *vma) +{ + VM_WARN_ON_FOLIO(!folio_test_hugetlb(folio), folio); + VM_WARN_ON_FOLIO(!folio_test_anon(folio), folio); + + if (PageAnonExclusive(&folio->page)) { + if (unlikely(folio_needs_cow_for_dma(vma, folio))) + return -EBUSY; + ClearPageAnonExclusive(&folio->page); + } + atomic_inc(&folio->_entire_mapcount); + return 0; +} + static inline void hugetlb_add_file_rmap(struct folio *folio) { VM_WARN_ON_FOLIO(!folio_test_hugetlb(folio), folio); @@ -225,6 +241,8 @@ static inline void hugetlb_remove_rmap(struct folio *folio)
static inline void __page_dup_rmap(struct page *page, bool compound) { + VM_WARN_ON(folio_test_hugetlb(page_folio(page))); + if (compound) { struct folio *folio = (struct folio *)page;
diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 0b3d6af04079..3a4a06f5e836 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -5354,8 +5354,7 @@ int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src, */ if (!folio_test_anon(pte_folio)) { hugetlb_add_file_rmap(pte_folio); - } else if (page_try_dup_anon_rmap(&pte_folio->page, - true, src_vma)) { + } else if (hugetlb_try_dup_anon_rmap(pte_folio, src_vma)) { pte_t src_pte_old = entry; struct folio *new_folio;