| Message ID | 20220930141931.174362-6-david@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | mm/ksm: break_ksm() cleanups and fixes | expand |
On Fri, Sep 30, 2022 at 04:19:29PM +0200, David Hildenbrand wrote: > +int walk_page_range_vma(struct vm_area_struct *vma, unsigned long start, > + unsigned long end, const struct mm_walk_ops *ops, > + void *private) > +{ > + struct mm_walk walk = { > + .ops = ops, > + .mm = vma->vm_mm, > + .vma = vma, > + .private = private, > + }; > + int err; > + > + if (start >= end || !walk.mm) > + return -EINVAL; > + if (start < vma->vm_start || end > vma->vm_end) > + return -EINVAL; > + > + mmap_assert_locked(walk.mm); > + > + err = walk_page_test(start, end, &walk); According to test_walk(): * @test_walk: caller specific callback function to determine whether * we walk over the current vma or not. Returning 0 means * "do page table walk over the current vma", returning * a negative value means "abort current page table walk * right now" and returning 1 means "skip the current vma" Since this helper has vma passed in, not sure whether this is needed at all? walk_page_vma_range() sounds slightly better to me as it does look more like an extension of walk_page_vma(), rather than sister version of walk_page_range_novma() (which works for "no backing VMA" case). But no strong opinion.
On 05.10.22 22:42, Peter Xu wrote: > On Fri, Sep 30, 2022 at 04:19:29PM +0200, David Hildenbrand wrote: >> +int walk_page_range_vma(struct vm_area_struct *vma, unsigned long start, >> + unsigned long end, const struct mm_walk_ops *ops, >> + void *private) >> +{ >> + struct mm_walk walk = { >> + .ops = ops, >> + .mm = vma->vm_mm, >> + .vma = vma, >> + .private = private, >> + }; >> + int err; >> + >> + if (start >= end || !walk.mm) >> + return -EINVAL; >> + if (start < vma->vm_start || end > vma->vm_end) >> + return -EINVAL; >> + >> + mmap_assert_locked(walk.mm); >> + >> + err = walk_page_test(start, end, &walk); > > According to test_walk(): > > * @test_walk: caller specific callback function to determine whether > * we walk over the current vma or not. Returning 0 means > * "do page table walk over the current vma", returning > * a negative value means "abort current page table walk > * right now" and returning 1 means "skip the current vma" > > Since this helper has vma passed in, not sure whether this is needed at > all? I kept it because walk_page_vma() similarly has it -- walk_page_vma() walks the whole VMA range. I do agree that it's kind of weird to have it like that. All users of walk_page_vma() don't use it, so we can just get rid of it there as well. Might make the walk slightly faster. > > walk_page_vma_range() sounds slightly better to me as it does look more > like an extension of walk_page_vma(), rather than sister version of > walk_page_range_novma() (which works for "no backing VMA" case). But no > strong opinion. > I matched that to walk_page_range_novma(). Now we have walk_page_range walk_page_vma walk_page_range_novma walk_page_range_vma
diff --git a/include/linux/pagewalk.h b/include/linux/pagewalk.h index f3fafb731ffd..2f8f6cc980b4 100644 --- a/include/linux/pagewalk.h +++ b/include/linux/pagewalk.h @@ -99,6 +99,9 @@ int walk_page_range_novma(struct mm_struct *mm, unsigned long start, unsigned long end, const struct mm_walk_ops *ops, pgd_t *pgd, void *private); +int walk_page_range_vma(struct vm_area_struct *vma, unsigned long start, + unsigned long end, const struct mm_walk_ops *ops, + void *private); int walk_page_vma(struct vm_area_struct *vma, const struct mm_walk_ops *ops, void *private); int walk_page_mapping(struct address_space *mapping, pgoff_t first_index, diff --git a/mm/pagewalk.c b/mm/pagewalk.c index 131b2b335b2c..757c075da231 100644 --- a/mm/pagewalk.c +++ b/mm/pagewalk.c @@ -514,6 +514,33 @@ int walk_page_range_novma(struct mm_struct *mm, unsigned long start, return __walk_page_range(start, end, &walk); } +int walk_page_range_vma(struct vm_area_struct *vma, unsigned long start, + unsigned long end, const struct mm_walk_ops *ops, + void *private) +{ + struct mm_walk walk = { + .ops = ops, + .mm = vma->vm_mm, + .vma = vma, + .private = private, + }; + int err; + + if (start >= end || !walk.mm) + return -EINVAL; + if (start < vma->vm_start || end > vma->vm_end) + return -EINVAL; + + mmap_assert_locked(walk.mm); + + err = walk_page_test(start, end, &walk); + if (err > 0) + return 0; + if (err < 0) + return err; + return __walk_page_range(start, end, &walk); +} + int walk_page_vma(struct vm_area_struct *vma, const struct mm_walk_ops *ops, void *private) {
Let's add walk_page_range_vma(), which is similar to walk_page_vma(), however, is only interested in a subset of the VMA range. To be used in KSM code to stop using follow_page() next. Signed-off-by: David Hildenbrand <david@redhat.com> --- include/linux/pagewalk.h | 3 +++ mm/pagewalk.c | 27 +++++++++++++++++++++++++++ 2 files changed, 30 insertions(+)