From: Andrew Morton <akpm@linux-foundation.org>
To: Miaohe Lin <linmiaohe@huawei.com>
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: Sat, 23 Jan 2021 18:01:07 -0800 [thread overview]
Message-ID: <20210123180107.95f54cc0849a6d8c6afa16ee@linux-foundation.org> (raw)
In-Reply-To: <2c691a87-42fd-63f6-6d7a-136be6572fab@huawei.com>
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.
next prev parent reply other threads:[~2021-01-24 2:01 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-09 8:01 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 [this message]
2021-01-25 2:04 ` Miaohe Lin
-- 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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