From: Dave Hansen <dave.hansen@intel.com>
To: Pavel Machek <pavel@ucw.cz>, Michal Hocko <mhocko@kernel.org>
Cc: vbabka@suse.cz, hpa@zytor.com, torvalds@linux-foundation.org,
ak@linux.intel.com, kernel list <linux-kernel@vger.kernel.org>,
tglx@linutronix.de, mingo@redhat.com, bp@alien8.de
Subject: Re: l1tf: Kernel suggests I throw away third of my memory. I'd rather not
Date: Wed, 17 Oct 2018 15:21:00 -0700 [thread overview]
Message-ID: <a428fb27-6fba-0bad-feac-81416cf9089c@intel.com> (raw)
In-Reply-To: <20181017113226.GA5176@amd>
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On 10/17/2018 04:32 AM, Pavel Machek wrote:
>> Well, that depends. Do you care about PROT_NONE attacks as well? If not
>> then no-swap would help you. But even then no-swap is rather theoretical
>> attack on a physical host unless you allow an arbitrary swapout to a
>> malicious user (e.g. allow a user controlled memcg hard limit that would
>> cause excessive local swapouts).
> PROT_NONE attack.. aha, so kernel stores not only information about
> swapped-out pages but also about file-backed pages that are currently
> not present? Hmm. That makes it more complex :-(.
There are also migration PTE entries that are "swap-like". They can
exist even if you swapoff -a.
Can we do better? Sure. I think we'd all be happy to review patches
that improve the situation if folks have simple ideas for improvement.
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next prev parent reply other threads:[~2018-10-17 22:21 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-17 10:56 Pavel Machek
2018-10-17 11:15 ` Michal Hocko
2018-10-17 11:32 ` Pavel Machek
2018-10-17 12:17 ` Michal Hocko
2018-10-17 22:21 ` Dave Hansen [this message]
2018-10-18 7:10 ` Vlastimil Babka
2018-10-17 14:08 ` Andi Kleen
2018-10-17 14:13 ` Vlastimil Babka
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