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Date:   Thu, 20 Jul 2023 11:32:28 +0100
From:   Will Deacon <will@kernel.org>
To:     Mark Brown <broonie@kernel.org>
Cc:     Hugh Dickins <hughd@google.com>,
        Lorenzo Stoakes <lstoakes@gmail.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Mike Kravetz <mike.kravetz@oracle.com>,
        Mike Rapoport <rppt@kernel.org>,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        Matthew Wilcox <willy@infradead.org>,
        David Hildenbrand <david@redhat.com>,
        Suren Baghdasaryan <surenb@google.com>,
        Qi Zheng <zhengqi.arch@bytedance.com>,
        Yang Shi <shy828301@gmail.com>,
        Mel Gorman <mgorman@techsingularity.net>,
        Peter Xu <peterx@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Yu Zhao <yuzhao@google.com>,
        Alistair Popple <apopple@nvidia.com>,
        Ralph Campbell <rcampbell@nvidia.com>,
        Ira Weiny <ira.weiny@intel.com>,
        Steven Price <steven.price@arm.com>,
        SeongJae Park <sj@kernel.org>,
        Huang Ying <ying.huang@intel.com>,
        Naoya Horiguchi <naoya.horiguchi@nec.com>,
        Christophe Leroy <christophe.leroy@csgroup.eu>,
        Zack Rusin <zackr@vmware.com>, Jason Gunthorpe <jgg@ziepe.ca>,
        Axel Rasmussen <axelrasmussen@google.com>,
        Anshuman Khandual <anshuman.khandual@arm.com>,
        Pasha Tatashin <pasha.tatashin@soleen.com>,
        Miaohe Lin <linmiaohe@huawei.com>,
        Minchan Kim <minchan@kernel.org>,
        Christoph Hellwig <hch@infradead.org>,
        Song Liu <song@kernel.org>,
        Thomas Hellstrom <thomas.hellstrom@linux.intel.com>,
        Ryan Roberts <ryan.roberts@arm.com>,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        regressions@leemhuis.info, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v2 12/32] mm/vmalloc: vmalloc_to_page() use
 pte_offset_kernel()
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On Tue, Jul 11, 2023 at 06:57:33PM +0100, Mark Brown wrote:
> On Tue, Jul 11, 2023 at 09:13:18AM -0700, Hugh Dickins wrote:
> > On Tue, 11 Jul 2023, Mark Brown wrote:
> > > On Mon, Jul 10, 2023 at 09:34:42PM -0700, Hugh Dickins wrote:
> > > 
> > > > I suppose I should ask you to try reverting this 0d1c81edc61e alone
> > > > from 6.5-rc1: the consistency of your bisection implies that it will
> > > > "fix" the issues, and it is a commit which we could drop.  It makes
> > > > me a little nervous, applying userspace-pagetable validation to kernel
> > > > pagetables, so I don't want to drop it; and it would really be cargo-
> > > > culting to drop it without understanding.  But we could drop it.
> > > 
> > > I did look at that, it doesn't revert cleanly by itself. ...
> > 
> > Right, that ptep_get() wrapper on the next line came in on top.
> > The patch to revert just 0d1c81edc61e is this:
> 
> Still investigating but I'm pretty convinced this is nothing to do with
> your commit/series and is just common or garden memory corruption that
> just happens to get tickled by your changes.  Sorry for the noise.

Did you get to the bottom of this? If not, do you have a reliable way to
reproduce the problem? I don't like the sound of memory corruption :(

Will