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Date:   Tue, 11 Jul 2023 16:48:14 +0200
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Subject: Re: [PATCH v2 12/32] mm/vmalloc: vmalloc_to_page() use
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To:     Mark Brown <broonie@kernel.org>, Hugh Dickins <hughd@google.com>
Cc:     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>,
        Will Deacon <will@kernel.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>,
        Lorenzo Stoakes <lstoakes@gmail.com>,
        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,
        linux-arm-kernel@lists.infradead.org,
        Linux kernel regressions list <regressions@lists.linux.dev>
References: <c1c9a74a-bc5b-15ea-e5d2-8ec34bc921d@google.com>
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From:   "Linux regression tracking #adding (Thorsten Leemhuis)" 
        <regressions@leemhuis.info>
Reply-To: Linux regressions mailing list <regressions@lists.linux.dev>
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Precedence: bulk

[CCing the regression list, as it should be in the loop for regressions:
https://docs.kernel.org/admin-guide/reporting-regressions.html]

[TLDR: I'm adding this report to the list of tracked Linux kernel
regressions; the text you find below is based on a few templates
paragraphs you might have encountered already in similar form.
See link in footer if these mails annoy you.]

On 10.07.23 16:42, Mark Brown wrote:
> On Thu, Jun 08, 2023 at 06:21:41PM -0700, Hugh Dickins wrote:
>> vmalloc_to_page() was using pte_offset_map() (followed by pte_unmap()),
>> but it's intended for userspace page tables: prefer pte_offset_kernel().
>>
>> Signed-off-by: Hugh Dickins <hughd@google.com>
>> Reviewed-by: Lorenzo Stoakes <lstoakes@gmail.com>
> 
> Currently Linus' tree is reliably failing to boot on pine64plus, an
> arm64 SBC.  Most other boards seem fine, though I am seeing some
> additional instability on Tritium which is another Allwinner platform,
> I've not dug into that yet and Tritium is generally less stable.
> 
> We end up seeing NULL or otherwise bad pointer dereferences, the
> [...]
> # first bad commit: [0d1c81edc61e553ed7a5db18fb8074c8b78e1538] mm/vmalloc: vmalloc_to_page() use pte_offset_kernel()

Thanks for the report. To be sure the issue doesn't fall through the
cracks unnoticed, I'm adding it to regzbot, the Linux kernel regression
tracking bot:

#regzbot ^introduced 0d1c81edc61e553ed7a5db18fb8074c8
#regzbot title mm/vmalloc: NULL or otherwise bad pointer dereferences on
ARM64
#regzbot ignore-activity

This isn't a regression? This issue or a fix for it are already
discussed somewhere else? It was fixed already? You want to clarify when
the regression started to happen? Or point out I got the title or
something else totally wrong? Then just reply and tell me -- ideally
while also telling regzbot about it, as explained by the page listed in
the footer of this mail.

Developers: When fixing the issue, remember to add 'Link:' tags pointing
to the report (the parent of this mail). See page linked in footer for
details.

Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat)
--
Everything you wanna know about Linux kernel regression tracking:
https://linux-regtracking.leemhuis.info/about/#tldr
That page also explains what to do if mails like this annoy you.