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This is a preparation for freeing empty PTE pages, no functional changes are expected. Signed-off-by: Qi Zheng --- Documentation/mm/split_page_table_lock.rst | 3 ++- arch/arm/mm/fault-armv.c | 2 +- arch/powerpc/mm/pgtable.c | 2 +- include/linux/mm.h | 4 ++-- mm/filemap.c | 2 +- mm/khugepaged.c | 4 ++-- mm/memory.c | 4 ++-- mm/mremap.c | 2 +- mm/page_vma_mapped.c | 2 +- mm/pgtable-generic.c | 21 ++++++++++++--------- mm/userfaultfd.c | 4 ++-- mm/vmscan.c | 2 +- 12 files changed, 28 insertions(+), 24 deletions(-) diff --git a/Documentation/mm/split_page_table_lock.rst b/Documentation/mm/= split_page_table_lock.rst index e4f6972eb6c04..e6a47d57531cd 100644 --- a/Documentation/mm/split_page_table_lock.rst +++ b/Documentation/mm/split_page_table_lock.rst @@ -18,7 +18,8 @@ There are helpers to lock/unlock a table and other access= or functions: pointer to its PTE table lock, or returns NULL if no PTE table; - pte_offset_map_nolock() maps PTE, returns pointer to PTE with pointer to its PTE table - lock (not taken), or returns NULL if no PTE table; + lock (not taken) and the value of its pmd entry, or returns NULL + if no PTE table; - pte_offset_map() maps PTE, returns pointer to PTE, or returns NULL if no PTE table; - pte_unmap() diff --git a/arch/arm/mm/fault-armv.c b/arch/arm/mm/fault-armv.c index 831793cd6ff94..db07e6a05eb6e 100644 --- a/arch/arm/mm/fault-armv.c +++ b/arch/arm/mm/fault-armv.c @@ -117,7 +117,7 @@ static int adjust_pte(struct vm_area_struct *vma, unsig= ned long address, * must use the nested version. This also means we need to * open-code the spin-locking. */ - pte =3D pte_offset_map_nolock(vma->vm_mm, pmd, address, &ptl); + pte =3D pte_offset_map_nolock(vma->vm_mm, pmd, NULL, address, &ptl); if (!pte) return 0; =20 diff --git a/arch/powerpc/mm/pgtable.c b/arch/powerpc/mm/pgtable.c index 7316396e452d8..9b67d2a1457ed 100644 --- a/arch/powerpc/mm/pgtable.c +++ b/arch/powerpc/mm/pgtable.c @@ -398,7 +398,7 @@ void assert_pte_locked(struct mm_struct *mm, unsigned l= ong addr) */ if (pmd_none(*pmd)) return; - pte =3D pte_offset_map_nolock(mm, pmd, addr, &ptl); + pte =3D pte_offset_map_nolock(mm, pmd, NULL, addr, &ptl); BUG_ON(!pte); assert_spin_locked(ptl); pte_unmap(pte); diff --git a/include/linux/mm.h b/include/linux/mm.h index 43b40334e9b28..b1ef2afe620c5 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2937,8 +2937,8 @@ static inline pte_t *pte_offset_map_lock(struct mm_st= ruct *mm, pmd_t *pmd, return pte; } =20 -pte_t *pte_offset_map_nolock(struct mm_struct *mm, pmd_t *pmd, - unsigned long addr, spinlock_t **ptlp); +pte_t *pte_offset_map_nolock(struct mm_struct *mm, pmd_t *pmd, pmd_t *pmdv= alp, + unsigned long addr, spinlock_t **ptlp); =20 #define pte_unmap_unlock(pte, ptl) do { \ spin_unlock(ptl); \ diff --git a/mm/filemap.c b/mm/filemap.c index 67c3f5136db33..3285dffb64cf8 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -3231,7 +3231,7 @@ static vm_fault_t filemap_fault_recheck_pte_none(stru= ct vm_fault *vmf) if (!(vmf->flags & FAULT_FLAG_ORIG_PTE_VALID)) return 0; =20 - ptep =3D pte_offset_map_nolock(vma->vm_mm, vmf->pmd, vmf->address, + ptep =3D pte_offset_map_nolock(vma->vm_mm, vmf->pmd, NULL, vmf->address, &vmf->ptl); if (unlikely(!ptep)) return VM_FAULT_NOPAGE; diff --git a/mm/khugepaged.c b/mm/khugepaged.c index cdd1d8655a76b..91b93259ee214 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -1009,7 +1009,7 @@ static int __collapse_huge_page_swapin(struct mm_stru= ct *mm, }; =20 if (!pte++) { - pte =3D pte_offset_map_nolock(mm, pmd, address, &ptl); + pte =3D pte_offset_map_nolock(mm, pmd, NULL, address, &ptl); if (!pte) { mmap_read_unlock(mm); result =3D SCAN_PMD_NULL; @@ -1598,7 +1598,7 @@ int collapse_pte_mapped_thp(struct mm_struct *mm, uns= igned long addr, if (userfaultfd_armed(vma) && !(vma->vm_flags & VM_SHARED)) pml =3D pmd_lock(mm, pmd); =20 - start_pte =3D pte_offset_map_nolock(mm, pmd, haddr, &ptl); + start_pte =3D pte_offset_map_nolock(mm, pmd, NULL, haddr, &ptl); if (!start_pte) /* mmap_lock + page lock should prevent this */ goto abort; if (!pml) diff --git a/mm/memory.c b/mm/memory.c index d6a9dcddaca4a..afd8a967fb953 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1108,7 +1108,7 @@ copy_pte_range(struct vm_area_struct *dst_vma, struct= vm_area_struct *src_vma, ret =3D -ENOMEM; goto out; } - src_pte =3D pte_offset_map_nolock(src_mm, src_pmd, addr, &src_ptl); + src_pte =3D pte_offset_map_nolock(src_mm, src_pmd, NULL, addr, &src_ptl); if (!src_pte) { pte_unmap_unlock(dst_pte, dst_ptl); /* ret =3D=3D 0 */ @@ -5671,7 +5671,7 @@ static vm_fault_t handle_pte_fault(struct vm_fault *v= mf) * it into a huge pmd: just retry later if so. */ vmf->pte =3D pte_offset_map_nolock(vmf->vma->vm_mm, vmf->pmd, - vmf->address, &vmf->ptl); + NULL, vmf->address, &vmf->ptl); if (unlikely(!vmf->pte)) return 0; vmf->orig_pte =3D ptep_get_lockless(vmf->pte); diff --git a/mm/mremap.c b/mm/mremap.c index e7ae140fc6409..f672d0218a6fe 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -175,7 +175,7 @@ static int move_ptes(struct vm_area_struct *vma, pmd_t = *old_pmd, err =3D -EAGAIN; goto out; } - new_pte =3D pte_offset_map_nolock(mm, new_pmd, new_addr, &new_ptl); + new_pte =3D pte_offset_map_nolock(mm, new_pmd, NULL, new_addr, &new_ptl); if (!new_pte) { pte_unmap_unlock(old_pte, old_ptl); err =3D -EAGAIN; diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c index ae5cc42aa2087..507701b7bcc1e 100644 --- a/mm/page_vma_mapped.c +++ b/mm/page_vma_mapped.c @@ -33,7 +33,7 @@ static bool map_pte(struct page_vma_mapped_walk *pvmw, sp= inlock_t **ptlp) * Though, in most cases, page lock already protects this. */ pvmw->pte =3D pte_offset_map_nolock(pvmw->vma->vm_mm, pvmw->pmd, - pvmw->address, ptlp); + NULL, pvmw->address, ptlp); if (!pvmw->pte) return false; =20 diff --git a/mm/pgtable-generic.c b/mm/pgtable-generic.c index a78a4adf711ac..443e3b34434a5 100644 --- a/mm/pgtable-generic.c +++ b/mm/pgtable-generic.c @@ -305,7 +305,7 @@ pte_t *__pte_offset_map(pmd_t *pmd, unsigned long addr,= pmd_t *pmdvalp) return NULL; } =20 -pte_t *pte_offset_map_nolock(struct mm_struct *mm, pmd_t *pmd, +pte_t *pte_offset_map_nolock(struct mm_struct *mm, pmd_t *pmd, pmd_t *pmdv= alp, unsigned long addr, spinlock_t **ptlp) { pmd_t pmdval; @@ -314,6 +314,8 @@ pte_t *pte_offset_map_nolock(struct mm_struct *mm, pmd_= t *pmd, pte =3D __pte_offset_map(pmd, addr, &pmdval); if (likely(pte)) *ptlp =3D pte_lockptr(mm, &pmdval); + if (pmdvalp) + *pmdvalp =3D pmdval; return pte; } =20 @@ -347,14 +349,15 @@ pte_t *pte_offset_map_nolock(struct mm_struct *mm, pm= d_t *pmd, * and disconnected table. Until pte_unmap(pte) unmaps and rcu_read_unloc= k()s * afterwards. * - * pte_offset_map_nolock(mm, pmd, addr, ptlp), above, is like pte_offset_m= ap(); - * but when successful, it also outputs a pointer to the spinlock in ptlp = - as - * pte_offset_map_lock() does, but in this case without locking it. This = helps - * the caller to avoid a later pte_lockptr(mm, *pmd), which might by that = time - * act on a changed *pmd: pte_offset_map_nolock() provides the correct spi= nlock - * pointer for the page table that it returns. In principle, the caller s= hould - * recheck *pmd once the lock is taken; in practice, no callsite needs tha= t - - * either the mmap_lock for write, or pte_same() check on contents, is eno= ugh. + * pte_offset_map_nolock(mm, pmd, pmdvalp, addr, ptlp), above, is like + * pte_offset_map(); but when successful, it also outputs a pointer to the + * spinlock in ptlp - as pte_offset_map_lock() does, but in this case with= out + * locking it. This helps the caller to avoid a later pte_lockptr(mm, *pm= d), + * which might by that time act on a changed *pmd: pte_offset_map_nolock() + * provides the correct spinlock pointer for the page table that it return= s. + * In principle, the caller should recheck *pmd once the lock is taken; Bu= t in + * most cases, either the mmap_lock for write, or pte_same() check on cont= ents, + * is enough. * * Note that free_pgtables(), used after unmapping detached vmas, or when * exiting the whole mm, does not take page table lock before freeing a pa= ge diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index 3b7715ecf292a..aa3c9cc51cc36 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -1143,7 +1143,7 @@ static int move_pages_pte(struct mm_struct *mm, pmd_t= *dst_pmd, pmd_t *src_pmd, src_addr, src_addr + PAGE_SIZE); mmu_notifier_invalidate_range_start(&range); retry: - dst_pte =3D pte_offset_map_nolock(mm, dst_pmd, dst_addr, &dst_ptl); + dst_pte =3D pte_offset_map_nolock(mm, dst_pmd, NULL, dst_addr, &dst_ptl); =20 /* Retry if a huge pmd materialized from under us */ if (unlikely(!dst_pte)) { @@ -1151,7 +1151,7 @@ static int move_pages_pte(struct mm_struct *mm, pmd_t= *dst_pmd, pmd_t *src_pmd, goto out; } =20 - src_pte =3D pte_offset_map_nolock(mm, src_pmd, src_addr, &src_ptl); + src_pte =3D pte_offset_map_nolock(mm, src_pmd, NULL, src_addr, &src_ptl); =20 /* * We held the mmap_lock for reading so MADV_DONTNEED diff --git a/mm/vmscan.c b/mm/vmscan.c index 31d13462571e6..b00cd560c0e43 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -3378,7 +3378,7 @@ static bool walk_pte_range(pmd_t *pmd, unsigned long = start, unsigned long end, DEFINE_MAX_SEQ(walk->lruvec); int old_gen, new_gen =3D lru_gen_from_seq(max_seq); =20 - pte =3D pte_offset_map_nolock(args->mm, pmd, start & PMD_MASK, &ptl); + pte =3D pte_offset_map_nolock(args->mm, pmd, NULL, start & PMD_MASK, &ptl= ); if (!pte) return false; if (!spin_trylock(ptl)) { --=20 2.20.1