linux-kernel - [PATCH 0/3] hugetlb: fixes for new vma lock series

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Date:   Tue,  4 Oct 2022 18:17:04 -0700
From:   Mike Kravetz <mike.kravetz@...cle.com>
To:     linux-mm@...ck.org, linux-kernel@...r.kernel.org
Cc:     Muchun Song <songmuchun@...edance.com>,
        Miaohe Lin <linmiaohe@...wei.com>,
        David Hildenbrand <david@...hat.com>,
        Sven Schnelle <svens@...ux.ibm.com>,
        Michal Hocko <mhocko@...e.com>, Peter Xu <peterx@...hat.com>,
        Naoya Horiguchi <naoya.horiguchi@...ux.dev>,
        "Aneesh Kumar K . V" <aneesh.kumar@...ux.vnet.ibm.com>,
        Andrea Arcangeli <aarcange@...hat.com>,
        "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
        Davidlohr Bueso <dave@...olabs.net>,
        Prakash Sangappa <prakash.sangappa@...cle.com>,
        James Houghton <jthoughton@...gle.com>,
        Mina Almasry <almasrymina@...gle.com>,
        Pasha Tatashin <pasha.tatashin@...een.com>,
        Axel Rasmussen <axelrasmussen@...gle.com>,
        Ray Fucillo <Ray.Fucillo@...ersystems.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Mike Kravetz <mike.kravetz@...cle.com>
Subject: [PATCH 0/3] hugetlb: fixes for new vma lock series

In review of the series "hugetlb: Use new vma lock for huge pmd sharing
synchronization", Miaohe Lin pointed out two key issues:
1) There is a race in the routine hugetlb_unmap_file_folio when locks
   are dropped and reacquired in the correct order [1].
2) With the switch to using vma lock for fault/truncate synchronization,
   we need to make sure lock exists for all VM_MAYSHARE vmas, not just
   vmas capable of pmd sharing.

These two issues are addressed here.  In addition, having a vma lock
present in all VM_MAYSHARE vmas, uncovered some issues around vma
splitting.  Those are also addressed.

The series "hugetlb: Use new vma lock for huge pmd sharing synchronization"
is currently in mm-stable and may soon be merged???  This is why I am
sending 'fixes' to that series instead of a new version.  If a new
version of the series is preferred, I can do that.  Just wanted to get
these changes out for review.

[1] https://lore.kernel.org/linux-mm/01f10195-7088-4462-6def-909549c75ef4@huawei.com/

Mike Kravetz (3):
  hugetlb: fix vma lock handling during split vma and range unmapping
  hugetlb: take hugetlb vma_lock when clearing vma_lock->vma pointer
  hugetlb: allocate vma lock for all sharable vmas

 mm/hugetlb.c | 127 +++++++++++++++++++++++++++------------------------
 mm/memory.c  |   4 --
 2 files changed, 68 insertions(+), 63 deletions(-)

-- 
2.37.3