From: Michal Hocko <mhocko@kernel.org>
To: Pavel Machek <pavel@ucw.cz>
Cc: "Weiss, Radu" <raduweis@amazon.com>,
virtualization@lists.linux-foundation.org, linux-mm@kvack.org,
mingo@kernel.org, Jann Horn <jannh@google.com>,
"Brooker, Marc" <mbrooker@amazon.com>,
"Singh, Balbir" <sblbir@amazon.com>,
len.brown@intel.com, bonzini@gnu.org, "Graf (AWS),
Alexander" <graf@amazon.de>,
keescook@chromium.org, linux-pm@vger.kernel.org, "Catangiu,
Adrian Costin" <acatan@amazon.com>,
Colm MacCarthaigh <colmmacc@amazon.com>,
fweimer@redhat.com, wad@chromium.org, linux-api@vger.kernel.org,
"Manwaring, Derek" <derekmn@amazon.com>,
rjw@rjwysocki.net, luto@amacapital.net, "Sandu,
Andrei" <sandreim@amazon.com>,
akpm@linux-foundation.org
Subject: Re: [RFC]: mm,power: introduce MADV_WIPEONSUSPEND
Date: Mon, 13 Jul 2020 10:02:06 +0200 [thread overview]
Message-ID: <20200713080206.GD16783@dhcp22.suse.cz> (raw)
In-Reply-To: <20200712072228.GB4721@duo.ucw.cz>
On Sun 12-07-20 09:22:28, Pavel Machek wrote:
> On Tue 2020-07-07 12:00:41, Colm MacCarthaigh wrote:
> >
> >
> > On 7 Jul 2020, at 9:37, Pavel Machek wrote:
> > > Please go through the thread and try to understand it.
> > >
> > > You'd need syscalls per get_randomness(), not per migration.
> >
> > I think one check per get_randomness() is sufficient, though putting it at
> > the end of the critical section rather than the beginning helps.
>
> Yeah, well, one syscall is still enough to make it useless.
I am sorry but I really do not follow. Why would you want to call a
syscall on each get_randomness invocation? Why is it not enough to
simply have a flag that tells that an external event has happened
and reinitialize if the flag is set? Yes this wouldn't be really sync
operation but does that matter? Is using a few random numbers from the
old pool just because the notifier hasn't processed and flag the
situation a major security concern?
Btw. let me just clarify that I am not by any means pushing a solution
like that. All I am saying is that MADV_WIPEONSUSPEND is inherently
subtle interface that we likely want to avoid.
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2020-07-13 8:02 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-03 10:34 [RFC]: mm,power: introduce MADV_WIPEONSUSPEND Catangiu, Adrian Costin
[not found] ` <B7793B7A-3660-4769-9B9A-FFCF250728BB-vV1OtcyAfmbQT0dZR+AlfA@public.gmane.org>
2020-07-03 11:04 ` Jann Horn
[not found] ` <CAG48ez2CpHX9i3YgkNyMHPz63ohjkaSZscMtwSHOFYN4VQow3Q-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2020-07-04 1:33 ` Colm MacCárthaigh
2020-07-06 12:09 ` Alexander Graf
2020-07-03 11:30 ` Michal Hocko
[not found] ` <20200703113026.GT18446-2MMpYkNvuYDjFM9bn6wA6Q@public.gmane.org>
2020-07-03 12:17 ` Rafael J. Wysocki
[not found] ` <CAJZ5v0g+ip-EuUsoK646W-jVSSUhbnvHKsWmFH0+F1w0oYSmGw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2020-07-03 22:39 ` Pavel Machek
2020-07-03 13:29 ` Jann Horn
[not found] ` <CAG48ez2O2z4L=n57Omwy6s1sWQkdTkPKiikhbfdVhiyd_TGRRw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2020-07-03 22:34 ` Pavel Machek
2020-07-03 22:53 ` Jann Horn
2020-07-07 7:38 ` Michal Hocko
[not found] ` <20200707073823.GA3820-2MMpYkNvuYDjFM9bn6wA6Q@public.gmane.org>
2020-07-07 8:07 ` Pavel Machek
2020-07-07 8:58 ` Michal Hocko
[not found] ` <20200707085847.GA5913-2MMpYkNvuYDjFM9bn6wA6Q@public.gmane.org>
2020-07-07 16:37 ` Pavel Machek
[not found] ` <E6B41570-E206-4458-921B-465B9EF74949@amazon.com>
[not found] ` <E6B41570-E206-4458-921B-465B9EF74949-vV1OtcyAfmbQT0dZR+AlfA@public.gmane.org>
2020-07-12 7:22 ` Pavel Machek
2020-07-13 8:02 ` Michal Hocko [this message]
2020-07-04 1:45 ` Colm MacCárthaigh
[not found] ` <BC9E44B2-D3C2-43C7-8F4B-A31477147368-vV1OtcyAfmbQT0dZR+AlfA@public.gmane.org>
2020-07-07 7:40 ` Michal Hocko
2020-07-03 22:44 ` Pavel Machek
2020-07-03 22:56 ` Jann Horn
[not found] ` <CAG48ez0oWQd42a-H-Dzw1Wq7HgB5PpFRGCZeYxP8ohxaoZHmvQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2020-07-04 11:48 ` Pavel Machek
2020-07-06 12:26 ` Alexander Graf
[not found] ` <57ab4fb3-3f82-d34f-ad74-2214b45a4dd9-vV1OtcyAfmbQT0dZR+AlfA@public.gmane.org>
2020-07-06 12:52 ` Jann Horn
[not found] ` <CAG48ez1tAAD+x6n07uCisXpqVpDUPX7xBWiKFkS3u2azHqd41A-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2020-07-06 13:14 ` Alexander Graf
2020-07-07 7:44 ` Michal Hocko
[not found] ` <20200707074425.GC3820-2MMpYkNvuYDjFM9bn6wA6Q@public.gmane.org>
2020-07-07 8:01 ` Alexander Graf
[not found] ` <efa55313-ce8a-bac9-15df-167f93c672b3-vV1OtcyAfmbQT0dZR+AlfA@public.gmane.org>
2020-07-07 9:14 ` Michal Hocko
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