linux-kernel - Re: [PATCH -mm v9 7/8] proc: export idle flag via kpageflags

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20150721163500.528bd39bbbc71abc3c8d429b@linux-foundation.org>
Date:	Tue, 21 Jul 2015 16:35:00 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Vladimir Davydov <vdavydov@...allels.com>
Cc:	Andres Lagar-Cavilla <andreslc@...gle.com>,
	Minchan Kim <minchan@...nel.org>,
	Raghavendra K T <raghavendra.kt@...ux.vnet.ibm.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Michal Hocko <mhocko@...e.cz>,
	Greg Thelen <gthelen@...gle.com>,
	Michel Lespinasse <walken@...gle.com>,
	David Rientjes <rientjes@...gle.com>,
	Pavel Emelyanov <xemul@...allels.com>,
	Cyrill Gorcunov <gorcunov@...nvz.org>,
	Jonathan Corbet <corbet@....net>, <linux-api@...r.kernel.org>,
	<linux-doc@...r.kernel.org>, <linux-mm@...ck.org>,
	<cgroups@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH -mm v9 7/8] proc: export idle flag via kpageflags

On Sun, 19 Jul 2015 15:31:16 +0300 Vladimir Davydov <vdavydov@...allels.com> wrote:

> As noted by Minchan, a benefit of reading idle flag from
> /proc/kpageflags is that one can easily filter dirty and/or unevictable
> pages while estimating the size of unused memory.
> 
> Note that idle flag read from /proc/kpageflags may be stale in case the
> page was accessed via a PTE, because it would be too costly to iterate
> over all page mappings on each /proc/kpageflags read to provide an
> up-to-date value. To make sure the flag is up-to-date one has to read
> /proc/kpageidle first.

Is there any value in teaching the regular old page scanner to update
these flags?  If it's doing an rmap scan anyway...

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/