From: Miaohe Lin <linmiaohe@huawei.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: <tglx@linutronix.de>, <dave.hansen@intel.com>,
<jpoimboe@redhat.com>, <linux-mm@kvack.org>,
<linux-kernel@vger.kernel.org>, Andi Kleen <ak@linux.intel.com>
Subject: Re: [PATCH] mm: Fix potential pte_unmap_unlock pte error
Date: Mon, 25 Jan 2021 10:04:19 +0800 [thread overview]
Message-ID: <372dc830-56ae-799c-6026-bb35c1803026@huawei.com> (raw)
In-Reply-To: <20210123180107.95f54cc0849a6d8c6afa16ee@linux-foundation.org>
Hi:
On 2021/1/24 10:01, Andrew Morton wrote:
> On Fri, 22 Jan 2021 16:27:23 +0800 Miaohe Lin <linmiaohe@huawei.com> wrote:
>
>> Hi Andrew:
>> On 2021/1/14 10:51, Miaohe Lin wrote:
>>> Hi:
>>> On 2021/1/11 1:14, Andi Kleen wrote:
>>>> On Sat, Jan 09, 2021 at 03:01:18AM -0500, Miaohe Lin wrote:
>>>>> Since commit 42e4089c7890 ("x86/speculation/l1tf: Disallow non privileged
>>>>> high MMIO PROT_NONE mappings"), when the first pfn modify is not allowed,
>>>>> we would break the loop with pte unchanged. Then the wrong pte - 1 would
>>>>> be passed to pte_unmap_unlock.
>>>>
>>>> Thanks.
>>>>
>>>> While the fix is correct, I'm not sure if it actually is a real bug. Is there
>>>> any architecture that would do something else than unlocking the underlying
>>>> page? If it's just the underlying page then it should be always the same
>>>> page, so no bug.
>>>>
>>>
>>> It's just a theoretical issue via code inspection.
>>
>> Should I send a new one without Cc statle or just drop this patch? Thanks.
>
> Your patch makes the code much less scary looking. I added Andi's
> observation to the changelog, removed the cc:stable and queued it up,
> thanks.
>
> .
>
Sounds reasonable. Many thanks for doing this!
next prev parent reply other threads:[~2021-01-25 2:15 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-09 8:01 [PATCH] mm: Fix potential pte_unmap_unlock pte error Miaohe Lin
2021-01-10 17:14 ` Andi Kleen
2021-01-14 2:51 ` Miaohe Lin
2021-01-22 8:27 ` Miaohe Lin
2021-01-24 2:01 ` Andrew Morton
2021-01-25 2:04 ` Miaohe Lin [this message]
-- strict thread matches above, loose matches on Subject: below --
2020-10-15 12:15 [PATCH] mm: fix " Shijie Luo
2020-10-15 12:58 ` osalvador
2020-10-15 13:19 ` Shijie Luo
2020-10-16 12:31 ` Michal Hocko
2020-10-16 12:37 ` osalvador
2020-10-16 13:11 ` Michal Hocko
2020-10-16 13:15 ` Michal Hocko
2020-10-16 13:42 ` Michal Hocko
2020-10-16 14:05 ` osalvador
2020-10-17 1:55 ` Shijie Luo
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