| Message ID | 20231204142146.91437-6-david@redhat.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm/rmap: interface overhaul | expand |
On 12/4/23 22:21, David Hildenbrand wrote: > 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. > > Note that try_to_unmap_one() does not need care. Easy to spot because > among all that nasty hugetlb special-casing in that function, we're not > using set_huge_pte_at() on the anon path -- well, and that code assumes > that we we would want to swapout. > > Signed-off-by: David Hildenbrand <david@redhat.com> Reviewed-by: Yin Fengwei <fengwei.yin@intel.com> > --- > include/linux/rmap.h | 20 ++++++++++++++++++++ > mm/rmap.c | 15 ++++++++++----- > 2 files changed, 30 insertions(+), 5 deletions(-) > > diff --git a/include/linux/rmap.h b/include/linux/rmap.h > index 8068c332e2ce5..3f38141b53b9d 100644 > --- a/include/linux/rmap.h > +++ b/include/linux/rmap.h > @@ -223,6 +223,26 @@ static inline int hugetlb_try_dup_anon_rmap(struct folio *folio, > return 0; > } > > +/* See page_try_share_anon_rmap() */ > +static inline int hugetlb_try_share_anon_rmap(struct folio *folio) > +{ > + VM_WARN_ON_FOLIO(!folio_test_anon(folio), folio); > + VM_WARN_ON_FOLIO(!PageAnonExclusive(&folio->page), folio); > + > + /* See page_try_share_anon_rmap() */ > + if (IS_ENABLED(CONFIG_HAVE_FAST_GUP)) > + smp_mb(); > + > + if (unlikely(folio_maybe_dma_pinned(folio))) > + return -EBUSY; > + ClearPageAnonExclusive(&folio->page); > + > + /* See page_try_share_anon_rmap() */ > + if (IS_ENABLED(CONFIG_HAVE_FAST_GUP)) > + smp_mb__after_atomic(); > + return 0; > +} > + > static inline void hugetlb_add_file_rmap(struct folio *folio) > { > VM_WARN_ON_FOLIO(folio_test_anon(folio), folio); > diff --git a/mm/rmap.c b/mm/rmap.c > index 5037581b79ec6..2f1af3958e687 100644 > --- a/mm/rmap.c > +++ b/mm/rmap.c > @@ -2105,13 +2105,18 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma, > !anon_exclusive, subpage); > > /* See page_try_share_anon_rmap(): clear PTE first. */ > - if (anon_exclusive && > - page_try_share_anon_rmap(subpage)) { > - if (folio_test_hugetlb(folio)) > + if (folio_test_hugetlb(folio)) { > + if (anon_exclusive && > + hugetlb_try_share_anon_rmap(folio)) { > set_huge_pte_at(mm, address, pvmw.pte, > pteval, hsz); > - else > - set_pte_at(mm, address, pvmw.pte, pteval); > + ret = false; > + page_vma_mapped_walk_done(&pvmw); > + break; > + } > + } else if (anon_exclusive && > + page_try_share_anon_rmap(page)) { > + set_pte_at(mm, address, pvmw.pte, pteval); > ret = false; > page_vma_mapped_walk_done(&pvmw); > break;
diff --git a/include/linux/rmap.h b/include/linux/rmap.h index 8068c332e2ce5..3f38141b53b9d 100644 --- a/include/linux/rmap.h +++ b/include/linux/rmap.h @@ -223,6 +223,26 @@ static inline int hugetlb_try_dup_anon_rmap(struct folio *folio, return 0; } +/* See page_try_share_anon_rmap() */ +static inline int hugetlb_try_share_anon_rmap(struct folio *folio) +{ + VM_WARN_ON_FOLIO(!folio_test_anon(folio), folio); + VM_WARN_ON_FOLIO(!PageAnonExclusive(&folio->page), folio); + + /* See page_try_share_anon_rmap() */ + if (IS_ENABLED(CONFIG_HAVE_FAST_GUP)) + smp_mb(); + + if (unlikely(folio_maybe_dma_pinned(folio))) + return -EBUSY; + ClearPageAnonExclusive(&folio->page); + + /* See page_try_share_anon_rmap() */ + if (IS_ENABLED(CONFIG_HAVE_FAST_GUP)) + smp_mb__after_atomic(); + return 0; +} + static inline void hugetlb_add_file_rmap(struct folio *folio) { VM_WARN_ON_FOLIO(folio_test_anon(folio), folio); diff --git a/mm/rmap.c b/mm/rmap.c index 5037581b79ec6..2f1af3958e687 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -2105,13 +2105,18 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma, !anon_exclusive, subpage); /* See page_try_share_anon_rmap(): clear PTE first. */ - if (anon_exclusive && - page_try_share_anon_rmap(subpage)) { - if (folio_test_hugetlb(folio)) + if (folio_test_hugetlb(folio)) { + if (anon_exclusive && + hugetlb_try_share_anon_rmap(folio)) { set_huge_pte_at(mm, address, pvmw.pte, pteval, hsz); - else - set_pte_at(mm, address, pvmw.pte, pteval); + ret = false; + page_vma_mapped_walk_done(&pvmw); + break; + } + } else if (anon_exclusive && + page_try_share_anon_rmap(page)) { + set_pte_at(mm, address, pvmw.pte, pteval); ret = false; page_vma_mapped_walk_done(&pvmw); break;
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. Note that try_to_unmap_one() does not need care. Easy to spot because among all that nasty hugetlb special-casing in that function, we're not using set_huge_pte_at() on the anon path -- well, and that code assumes that we we would want to swapout. Signed-off-by: David Hildenbrand <david@redhat.com> --- include/linux/rmap.h | 20 ++++++++++++++++++++ mm/rmap.c | 15 ++++++++++----- 2 files changed, 30 insertions(+), 5 deletions(-)