From: David Hildenbrand <david@redhat.com>
To: Karim Manaouil <kmanaouilinux@gmail.com>, npiggin@gmail.com
Cc: akpm@linux-foundation.org, mike.kravetz@oracle.com, linux-mm@kvack.org
Subject: Re: mm: Question: pte SMP data race in do_anomyous_page()?
Date: Thu, 25 May 2023 14:55:30 +0200 [thread overview]
Message-ID: <46ad119c-b129-e983-031b-d71aacad6a20@redhat.com> (raw)
In-Reply-To: <ZG8zMF6jMWdiBpP+@ed.ac.uk>
On 25.05.23 12:06, Karim Manaouil wrote:
> Hi,
>
> In do_anonymous_page(), a new page is allocated and zeroed, and the
> corresponding page struct is initialised (setting flags PageUptodate,
> PageSwapBacked, etc. and initialising the various counters).
>
> Then, set_pte_at() is called directly without calling smp_wmb() to make
> the updates above visible on other CPUs.
>
> This could race with a page table walker. The walker can read the new pte
> and try to access the page struct or the page content before the changes
> above were made visible.
Only after acquiring the page table lock (which the writer first has to
release), right?
--
Thanks,
David / dhildenb
next prev parent reply other threads:[~2023-05-25 12:55 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-25 10:06 Karim Manaouil
2023-05-25 12:55 ` David Hildenbrand [this message]
[not found] ` <ZHB2wyNtHn6qRWZB@ed.ac.uk>
2023-05-26 9:12 ` David Hildenbrand
2023-05-31 4:55 ` Alistair Popple
2023-05-31 7:27 ` David Hildenbrand
2023-05-31 12:54 ` Alistair Popple
2023-05-25 13:53 ` Matthew Wilcox
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