From: Pavel Machek <pavel@denx.de>
To: Laura Abbott <labbott@redhat.com>
Cc: Laura Abbott <labbott@fedoraproject.org>,
Andrew Morton <akpm@linux-foundation.org>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Vlastimil Babka <vbabka@suse.cz>, Michal Hocko <mhocko@suse.com>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
Len Brown <len.brown@intel.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
kernel-hardening@lists.openwall.com,
Kees Cook <keescook@chromium.org>,
linux-pm@vger.kernel.org
Subject: Re: [PATCHv2 2/2] mm/page_poisoning.c: Allow for zero poisoning
Date: Sat, 30 Jan 2016 16:30:54 +0100 [thread overview]
Message-ID: <20160130153053.GA4859@amd> (raw)
In-Reply-To: <56ABDB4A.2040709@redhat.com>
Hi!
> >>By default, page poisoning uses a poison value (0xaa) on free. If this
> >>is changed to 0, the page is not only sanitized but zeroing on alloc
> >>with __GFP_ZERO can be skipped as well. The tradeoff is that detecting
> >>corruption from the poisoning is harder to detect. This feature also
> >>cannot be used with hibernation since pages are not guaranteed to be
> >>zeroed after hibernation.
> >
> >So... this makes kernel harder to debug for performance advantage...?
> >If so.. how big is the performance advantage?
>
> The performance advantage really depends on the benchmark you are
> running.
You are trying to improve performance, so you should publish at least
one benchmark where it helps.
Alternatively, quote kernel build times with and without the
patch.
If it speeds kernel compile twice, I guess I may even help with
hibernation support. If it makes kernel compile faster by .00000034%
(or slows it down), we should probably simply ignore this patch.
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
WARNING: multiple messages have this Message-ID (diff)
From: Pavel Machek <pavel@denx.de>
To: Laura Abbott <labbott@redhat.com>
Cc: Laura Abbott <labbott@fedoraproject.org>,
Andrew Morton <akpm@linux-foundation.org>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Vlastimil Babka <vbabka@suse.cz>, Michal Hocko <mhocko@suse.com>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
Len Brown <len.brown@intel.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
kernel-hardening@lists.openwall.com,
Kees Cook <keescook@chromium.org>,
linux-pm@vger.kernel.org
Subject: Re: [PATCHv2 2/2] mm/page_poisoning.c: Allow for zero poisoning
Date: Sat, 30 Jan 2016 16:30:54 +0100 [thread overview]
Message-ID: <20160130153053.GA4859@amd> (raw)
In-Reply-To: <56ABDB4A.2040709@redhat.com>
Hi!
> >>By default, page poisoning uses a poison value (0xaa) on free. If this
> >>is changed to 0, the page is not only sanitized but zeroing on alloc
> >>with __GFP_ZERO can be skipped as well. The tradeoff is that detecting
> >>corruption from the poisoning is harder to detect. This feature also
> >>cannot be used with hibernation since pages are not guaranteed to be
> >>zeroed after hibernation.
> >
> >So... this makes kernel harder to debug for performance advantage...?
> >If so.. how big is the performance advantage?
>
> The performance advantage really depends on the benchmark you are
> running.
You are trying to improve performance, so you should publish at least
one benchmark where it helps.
Alternatively, quote kernel build times with and without the
patch.
If it speeds kernel compile twice, I guess I may even help with
hibernation support. If it makes kernel compile faster by .00000034%
(or slows it down), we should probably simply ignore this patch.
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
WARNING: multiple messages have this Message-ID (diff)
From: Pavel Machek <pavel@denx.de>
To: Laura Abbott <labbott@redhat.com>
Cc: Laura Abbott <labbott@fedoraproject.org>,
Andrew Morton <akpm@linux-foundation.org>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Vlastimil Babka <vbabka@suse.cz>, Michal Hocko <mhocko@suse.com>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
Len Brown <len.brown@intel.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
kernel-hardening@lists.openwall.com,
Kees Cook <keescook@chromium.org>,
linux-pm@vger.kernel.org
Subject: [kernel-hardening] Re: [PATCHv2 2/2] mm/page_poisoning.c: Allow for zero poisoning
Date: Sat, 30 Jan 2016 16:30:54 +0100 [thread overview]
Message-ID: <20160130153053.GA4859@amd> (raw)
In-Reply-To: <56ABDB4A.2040709@redhat.com>
Hi!
> >>By default, page poisoning uses a poison value (0xaa) on free. If this
> >>is changed to 0, the page is not only sanitized but zeroing on alloc
> >>with __GFP_ZERO can be skipped as well. The tradeoff is that detecting
> >>corruption from the poisoning is harder to detect. This feature also
> >>cannot be used with hibernation since pages are not guaranteed to be
> >>zeroed after hibernation.
> >
> >So... this makes kernel harder to debug for performance advantage...?
> >If so.. how big is the performance advantage?
>
> The performance advantage really depends on the benchmark you are
> running.
You are trying to improve performance, so you should publish at least
one benchmark where it helps.
Alternatively, quote kernel build times with and without the
patch.
If it speeds kernel compile twice, I guess I may even help with
hibernation support. If it makes kernel compile faster by .00000034%
(or slows it down), we should probably simply ignore this patch.
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
next prev parent reply other threads:[~2016-01-30 15:30 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-29 2:38 [PATCHv2 0/2] Sanitization of buddy pages Laura Abbott
2016-01-29 2:38 ` [kernel-hardening] " Laura Abbott
2016-01-29 2:38 ` Laura Abbott
2016-01-29 2:38 ` [PATCHv2 1/2] mm/page_poison.c: Enable PAGE_POISONING as a separate option Laura Abbott
2016-01-29 2:38 ` [kernel-hardening] " Laura Abbott
2016-01-29 2:38 ` Laura Abbott
2016-01-29 2:38 ` [PATCHv2 2/2] mm/page_poisoning.c: Allow for zero poisoning Laura Abbott
2016-01-29 2:38 ` [kernel-hardening] " Laura Abbott
2016-01-29 2:38 ` Laura Abbott
2016-01-29 3:55 ` Rafael J. Wysocki
2016-01-29 3:55 ` [kernel-hardening] " Rafael J. Wysocki
2016-01-29 3:55 ` Rafael J. Wysocki
2016-01-29 4:46 ` Kees Cook
2016-01-29 4:46 ` [kernel-hardening] " Kees Cook
2016-01-29 4:46 ` Kees Cook
2016-01-29 21:32 ` Laura Abbott
2016-01-29 21:32 ` [kernel-hardening] " Laura Abbott
2016-01-29 21:32 ` Laura Abbott
2016-01-29 21:32 ` Laura Abbott
2016-01-29 10:45 ` Pavel Machek
2016-01-29 10:45 ` [kernel-hardening] " Pavel Machek
2016-01-29 10:45 ` Pavel Machek
2016-01-29 21:36 ` Laura Abbott
2016-01-29 21:36 ` [kernel-hardening] " Laura Abbott
2016-01-29 21:36 ` Laura Abbott
2016-01-30 15:30 ` Pavel Machek [this message]
2016-01-30 15:30 ` [kernel-hardening] " Pavel Machek
2016-01-30 15:30 ` Pavel Machek
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20160130153053.GA4859@amd \
--to=pavel@denx.de \
--cc=akpm@linux-foundation.org \
--cc=keescook@chromium.org \
--cc=kernel-hardening@lists.openwall.com \
--cc=kirill.shutemov@linux.intel.com \
--cc=labbott@fedoraproject.org \
--cc=labbott@redhat.com \
--cc=len.brown@intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linux-pm@vger.kernel.org \
--cc=mhocko@suse.com \
--cc=rjw@rjwysocki.net \
--cc=vbabka@suse.cz \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.