Messages in this thread | | | From | James Houghton <> | Date | Wed, 30 Nov 2022 18:29:04 -0500 | Subject | Re: [RFC PATCH v2 06/47] hugetlb: extend vma lock for shared vmas |
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On Wed, Nov 30, 2022 at 4:01 PM Peter Xu <peterx@redhat.com> wrote: > > On Fri, Oct 21, 2022 at 04:36:22PM +0000, James Houghton wrote: > > This allows us to add more data into the shared structure, which we will > > use to store whether or not HGM is enabled for this VMA or not, as HGM > > is only available for shared mappings. > > > > It may be better to include HGM as a VMA flag instead of extending the > > VMA lock structure. > > > > Signed-off-by: James Houghton <jthoughton@google.com> > > --- > > include/linux/hugetlb.h | 4 +++ > > mm/hugetlb.c | 65 +++++++++++++++++++++-------------------- > > 2 files changed, 37 insertions(+), 32 deletions(-) > > > > diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h > > index a899bc76d677..534958499ac4 100644 > > --- a/include/linux/hugetlb.h > > +++ b/include/linux/hugetlb.h > > @@ -121,6 +121,10 @@ struct hugetlb_vma_lock { > > struct vm_area_struct *vma; > > }; > > > > +struct hugetlb_shared_vma_data { > > + struct hugetlb_vma_lock vma_lock; > > +}; > > How about add a comment above hugetlb_vma_lock showing how it should be > used correctly? We lacked documents on the lock for pmd sharing > protections, now if to reuse the same lock for HGM pgtables I think some > doc will definitely help. > > To summarize, I think so far it means: > > - Read lock needed when one wants to stablize VM_SHARED pgtables (covers > both pmd shared pgtables or hgm low-level pgtables) > > - Write lock needed when one wants to release VM_SHARED pgtable pages > (covers both pmd unshare or releasing hgm low-level pgtables) > > Or something like that.
Will do. I'll make this change together with the rmap comment update ("rmap: update hugetlb lock comment for HGM").
- James
> > -- > Peter Xu >
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