diff options
Diffstat (limited to 'mm/rmap.c')
| -rw-r--r-- | mm/rmap.c | 100 |
1 files changed, 65 insertions, 35 deletions
diff --git a/mm/rmap.c b/mm/rmap.c index 0e179c823e0a..b6743c2b8b5f 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1551,24 +1551,39 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma, * To call huge_pmd_unshare, i_mmap_rwsem must be * held in write mode. Caller needs to explicitly * do this outside rmap routines. + * + * We also must hold hugetlb vma_lock in write mode. + * Lock order dictates acquiring vma_lock BEFORE + * i_mmap_rwsem. We can only try lock here and fail + * if unsuccessful. */ - VM_BUG_ON(!anon && !(flags & TTU_RMAP_LOCKED)); - if (!anon && huge_pmd_unshare(mm, vma, address, pvmw.pte)) { - flush_tlb_range(vma, range.start, range.end); - mmu_notifier_invalidate_range(mm, range.start, - range.end); - - /* - * The ref count of the PMD page was dropped - * which is part of the way map counting - * is done for shared PMDs. Return 'true' - * here. When there is no other sharing, - * huge_pmd_unshare returns false and we will - * unmap the actual page and drop map count - * to zero. - */ - page_vma_mapped_walk_done(&pvmw); - break; + if (!anon) { + VM_BUG_ON(!(flags & TTU_RMAP_LOCKED)); + if (!hugetlb_vma_trylock_write(vma)) { + page_vma_mapped_walk_done(&pvmw); + ret = false; + break; + } + if (huge_pmd_unshare(mm, vma, address, pvmw.pte)) { + hugetlb_vma_unlock_write(vma); + flush_tlb_range(vma, + range.start, range.end); + mmu_notifier_invalidate_range(mm, + range.start, range.end); + /* + * The ref count of the PMD page was + * dropped which is part of the way map + * counting is done for shared PMDs. + * Return 'true' here. When there is + * no other sharing, huge_pmd_unshare + * returns false and we will unmap the + * actual page and drop map count + * to zero. + */ + page_vma_mapped_walk_done(&pvmw); + break; + } + hugetlb_vma_unlock_write(vma); } pteval = huge_ptep_clear_flush(vma, address, pvmw.pte); } else { @@ -1926,26 +1941,41 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma, * To call huge_pmd_unshare, i_mmap_rwsem must be * held in write mode. Caller needs to explicitly * do this outside rmap routines. + * + * We also must hold hugetlb vma_lock in write mode. + * Lock order dictates acquiring vma_lock BEFORE + * i_mmap_rwsem. We can only try lock here and + * fail if unsuccessful. */ - VM_BUG_ON(!anon && !(flags & TTU_RMAP_LOCKED)); - if (!anon && huge_pmd_unshare(mm, vma, address, pvmw.pte)) { - flush_tlb_range(vma, range.start, range.end); - mmu_notifier_invalidate_range(mm, range.start, - range.end); - - /* - * The ref count of the PMD page was dropped - * which is part of the way map counting - * is done for shared PMDs. Return 'true' - * here. When there is no other sharing, - * huge_pmd_unshare returns false and we will - * unmap the actual page and drop map count - * to zero. - */ - page_vma_mapped_walk_done(&pvmw); - break; + if (!anon) { + VM_BUG_ON(!(flags & TTU_RMAP_LOCKED)); + if (!hugetlb_vma_trylock_write(vma)) { + page_vma_mapped_walk_done(&pvmw); + ret = false; + break; + } + if (huge_pmd_unshare(mm, vma, address, pvmw.pte)) { + hugetlb_vma_unlock_write(vma); + flush_tlb_range(vma, + range.start, range.end); + mmu_notifier_invalidate_range(mm, + range.start, range.end); + + /* + * The ref count of the PMD page was + * dropped which is part of the way map + * counting is done for shared PMDs. + * Return 'true' here. When there is + * no other sharing, huge_pmd_unshare + * returns false and we will unmap the + * actual page and drop map count + * to zero. + */ + page_vma_mapped_walk_done(&pvmw); + break; + } + hugetlb_vma_unlock_write(vma); } - /* Nuke the hugetlb page table entry */ pteval = huge_ptep_clear_flush(vma, address, pvmw.pte); } else { |