Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Fri, 11 Jun 2021 11:29:31 -0700 (PDT)
From:   Hugh Dickins <hughd@google.com>
To:     Andrew Morton <akpm@linux-foundation.org>
cc:     Hugh Dickins <hughd@google.com>,
        "Kirill A. Shutemov" <kirill@shutemov.name>,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        Yang Shi <shy828301@gmail.com>,
        Wang Yugui <wangyugui@e16-tech.com>,
        Matthew Wilcox <willy@infradead.org>,
        Alistair Popple <apopple@nvidia.com>,
        Ralph Campbell <rcampbell@nvidia.com>, Zi Yan <ziy@nvidia.com>,
        Peter Xu <peterx@redhat.com>, Will Deacon <will@kernel.org>,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 11/11] mm/thp: another PVMW_SYNC fix in
 page_vma_mapped_walk()
In-Reply-To: <20210610094312.kzhhqyz4abe2yizg@box.shutemov.name>
Message-ID: <3f16d6ce-44ec-6d9e-d64-d7f750dc632@google.com>
References: <589b358c-febc-c88e-d4c2-7834b37fa7bf@google.com> <1bdf384c-8137-a149-2a1e-475a4791c3c@google.com> <20210610094312.kzhhqyz4abe2yizg@box.shutemov.name>
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Precedence: bulk

On Thu, 10 Jun 2021, Kirill A. Shutemov wrote:
> On Wed, Jun 09, 2021 at 11:54:46PM -0700, Hugh Dickins wrote:
> > Aha!  Shouldn't that quick scan over pte_none()s make sure that it holds
> > ptlock in the PVMW_SYNC case?  That too might have been responsible for
> > BUGs or WARNs in split_huge_page_to_list() or its unmap_page(), though
> > I've never seen any.
> > 
> > Fixes: ace71a19cec5 ("mm: introduce page_vma_mapped_walk()")
> > Signed-off-by: Hugh Dickins <hughd@google.com>
> > Cc: <stable@vger.kernel.org>
> 
> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>

Thanks Kirill.

And Wang Yugui has now reported the good news, that this afterthought
patch finally fixes the unmap_page() BUGs they were hitting on 5.10.

Andrew, please add a link to
https://lore.kernel.org/linux-mm/20210412180659.B9E3.409509F4@e16-tech.com/
and
Tested-by: Wang Yugui <wangyugui@e16-tech.com>

Thanks,
Hugh