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From:   Shakeel Butt <shakeelb@google.com>
Date:   Wed, 7 Jul 2021 13:22:27 -0700
Message-ID: <CALvZod4Tm_4mmNPW-5yfDPdOdukEmmZ1sqYpL9qUbiEXTms2dw@mail.gmail.com>
Subject: Re: [PATCH 3/4] mm/rmap: fix new bug: premature return from page_mlock_one()
To:     Hugh Dickins <hughd@google.com>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Alistair Popple <apopple@nvidia.com>,
        Jason Gunthorpe <jgg@nvidia.com>,
        Ralph Campbell <rcampbell@nvidia.com>,
        Christoph Hellwig <hch@lst.de>, Yang Shi <shy828301@gmail.com>,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Linux MM <linux-mm@kvack.org>
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On Wed, Jul 7, 2021 at 1:11 PM Hugh Dickins <hughd@google.com> wrote:
>
> In the unlikely race case that page_mlock_one() finds VM_LOCKED has been
> cleared by the time it got page table lock, page_vma_mapped_walk_done()
> must be called before returning, either explicitly, or by a final call
> to page_vma_mapped_walk() - otherwise the page table remains locked.
>
> Fixes: cd62734ca60d ("mm/rmap: split try_to_munlock from try_to_unmap")
> Signed-off-by: Hugh Dickins <hughd@google.com>

Reviewed-by: Shakeel Butt <shakeelb@google.com>