Messages in this thread | | | Date | Mon, 27 Jun 2022 17:56:51 +0530 | Subject | Re: [RFC PATCH 04/26] hugetlb: make huge_pte_lockptr take an explicit shift argument. | From | "manish.mishra" <> |
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On 24/06/22 11:06 pm, James Houghton wrote: > This is needed to handle PTL locking with high-granularity mapping. We > won't always be using the PMD-level PTL even if we're using the 2M > hugepage hstate. It's possible that we're dealing with 4K PTEs, in which > case, we need to lock the PTL for the 4K PTE. > > Signed-off-by: James Houghton <jthoughton@google.com> > --- > arch/powerpc/mm/pgtable.c | 3 ++- > include/linux/hugetlb.h | 19 ++++++++++++++----- > mm/hugetlb.c | 9 +++++---- > mm/migrate.c | 3 ++- > mm/page_vma_mapped.c | 3 ++- > 5 files changed, 25 insertions(+), 12 deletions(-) > > diff --git a/arch/powerpc/mm/pgtable.c b/arch/powerpc/mm/pgtable.c > index e6166b71d36d..663d591a8f08 100644 > --- a/arch/powerpc/mm/pgtable.c > +++ b/arch/powerpc/mm/pgtable.c > @@ -261,7 +261,8 @@ int huge_ptep_set_access_flags(struct vm_area_struct *vma, > > psize = hstate_get_psize(h); > #ifdef CONFIG_DEBUG_VM > - assert_spin_locked(huge_pte_lockptr(h, vma->vm_mm, ptep)); > + assert_spin_locked(huge_pte_lockptr(huge_page_shift(h), > + vma->vm_mm, ptep)); > #endif > > #else > diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h > index 498a4ae3d462..5fe1db46d8c9 100644 > --- a/include/linux/hugetlb.h > +++ b/include/linux/hugetlb.h > @@ -868,12 +868,11 @@ static inline gfp_t htlb_modify_alloc_mask(struct hstate *h, gfp_t gfp_mask) > return modified_mask; > } > > -static inline spinlock_t *huge_pte_lockptr(struct hstate *h, > +static inline spinlock_t *huge_pte_lockptr(unsigned int shift, > struct mm_struct *mm, pte_t *pte) > { > - if (huge_page_size(h) == PMD_SIZE) > + if (shift == PMD_SHIFT) > return pmd_lockptr(mm, (pmd_t *) pte); > - VM_BUG_ON(huge_page_size(h) == PAGE_SIZE);
I may have wrong understanding here, is per pmd lock for reducing
contention, if that is the case should be take per pmd lock of
PAGE_SIZE too and page_table_lock for anything higer than PMD.
> return &mm->page_table_lock; > } > > @@ -1076,7 +1075,7 @@ static inline gfp_t htlb_modify_alloc_mask(struct hstate *h, gfp_t gfp_mask) > return 0; > } > > -static inline spinlock_t *huge_pte_lockptr(struct hstate *h, > +static inline spinlock_t *huge_pte_lockptr(unsigned int shift, > struct mm_struct *mm, pte_t *pte) > { > return &mm->page_table_lock; > @@ -1116,7 +1115,17 @@ static inline spinlock_t *huge_pte_lock(struct hstate *h, > { > spinlock_t *ptl; > > - ptl = huge_pte_lockptr(h, mm, pte); > + ptl = huge_pte_lockptr(huge_page_shift(h), mm, pte); > + spin_lock(ptl); > + return ptl; > +} > + > +static inline spinlock_t *huge_pte_lock_shift(unsigned int shift, > + struct mm_struct *mm, pte_t *pte) > +{ > + spinlock_t *ptl; > + > + ptl = huge_pte_lockptr(shift, mm, pte); > spin_lock(ptl); > return ptl; > } > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index 0eec34edf3b2..d6d0d4c03def 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -4817,7 +4817,7 @@ int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src, > continue; > > dst_ptl = huge_pte_lock(h, dst, dst_pte); > - src_ptl = huge_pte_lockptr(h, src, src_pte); > + src_ptl = huge_pte_lockptr(huge_page_shift(h), src, src_pte); > spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); > entry = huge_ptep_get(src_pte); > dst_entry = huge_ptep_get(dst_pte); > @@ -4894,7 +4894,8 @@ int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src, > > /* Install the new huge page if src pte stable */ > dst_ptl = huge_pte_lock(h, dst, dst_pte); > - src_ptl = huge_pte_lockptr(h, src, src_pte); > + src_ptl = huge_pte_lockptr(huge_page_shift(h), > + src, src_pte); > spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); > entry = huge_ptep_get(src_pte); > if (!pte_same(src_pte_old, entry)) { > @@ -4948,7 +4949,7 @@ static void move_huge_pte(struct vm_area_struct *vma, unsigned long old_addr, > pte_t pte; > > dst_ptl = huge_pte_lock(h, mm, dst_pte); > - src_ptl = huge_pte_lockptr(h, mm, src_pte); > + src_ptl = huge_pte_lockptr(huge_page_shift(h), mm, src_pte); > > /* > * We don't have to worry about the ordering of src and dst ptlocks > @@ -6024,7 +6025,7 @@ int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm, > page_in_pagecache = true; > } > > - ptl = huge_pte_lockptr(h, dst_mm, dst_pte); > + ptl = huge_pte_lockptr(huge_page_shift(h), dst_mm, dst_pte); > spin_lock(ptl); > > /* > diff --git a/mm/migrate.c b/mm/migrate.c > index e51588e95f57..a8a960992373 100644 > --- a/mm/migrate.c > +++ b/mm/migrate.c > @@ -318,7 +318,8 @@ void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd, > void migration_entry_wait_huge(struct vm_area_struct *vma, > struct mm_struct *mm, pte_t *pte) > { > - spinlock_t *ptl = huge_pte_lockptr(hstate_vma(vma), mm, pte); > + spinlock_t *ptl = huge_pte_lockptr(huge_page_shift(hstate_vma(vma)), > + mm, pte); > __migration_entry_wait(mm, pte, ptl); > } > > diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c > index c10f839fc410..8921dd4e41b1 100644 > --- a/mm/page_vma_mapped.c > +++ b/mm/page_vma_mapped.c > @@ -174,7 +174,8 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw) > if (!pvmw->pte) > return false; > > - pvmw->ptl = huge_pte_lockptr(hstate, mm, pvmw->pte); > + pvmw->ptl = huge_pte_lockptr(huge_page_shift(hstate), > + mm, pvmw->pte); > spin_lock(pvmw->ptl); > if (!check_pte(pvmw)) > return not_found(pvmw);
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