From: David Rientjes <rientjes@google.com>
To: Wen Congyang <wency@cn.fujitsu.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
linux-doc@vger.kernel.org, Rob Landley <rob@landley.net>,
Andrew Morton <akpm@linux-foundation.org>,
Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>,
Lai Jiangshan <laijs@cn.fujitsu.com>,
Jiang Liu <jiang.liu@huawei.com>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
Minchan Kim <minchan.kim@gmail.com>, Mel Gorman <mgorman@suse.de>,
Yinghai Lu <yinghai@kernel.org>,
"rusty@rustcorp.com.au" <rusty@rustcorp.com.au>
Subject: Re: [PART6 Patch] mempolicy: fix is_valid_nodemask()
Date: Wed, 31 Oct 2012 11:21:32 -0700 (PDT) [thread overview]
Message-ID: <alpine.DEB.2.00.1210311119000.8809@chino.kir.corp.google.com> (raw)
In-Reply-To: <1351675458-11859-2-git-send-email-wency@cn.fujitsu.com>
On Wed, 31 Oct 2012, Wen Congyang wrote:
> From: Lai Jiangshan <laijs@cn.fujitsu.com>
>
> is_valid_nodemask() is introduced by 19770b32. but it does not match
> its comments, because it does not check the zone which > policy_zone.
>
> Also in b377fd, this commits told us, if highest zone is ZONE_MOVABLE,
> we should also apply memory policies to it. so ZONE_MOVABLE should be valid zone
> for policies. is_valid_nodemask() need to be changed to match it.
>
> Fix: check all zones, even its zoneid > policy_zone.
> Use nodes_intersects() instead open code to check it.
>
This changes the semantics of MPOL_BIND to be considerably different than
what it is today: slab allocations are no longer bound by such a policy
which isn't consistent with what userspace expects or is specified by
set_mempolicy() and there's no way, with your patch, to actually specify
that we don't care about ZONE_MOVABLE and that the slab allocations
_should_ actually be allocated on movable-only zones. You have to respect
cases where people aren't interested in node hotplug and not cause a
regression.
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next prev parent reply other threads:[~2012-10-31 18:21 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-31 9:24 [PART6 Patch] memory-hotplug: bugfix for movable node Wen Congyang
2012-10-31 9:24 ` [PART6 Patch] mempolicy: fix is_valid_nodemask() Wen Congyang
2012-10-31 18:21 ` David Rientjes [this message]
2012-11-02 6:04 ` Kamezawa Hiroyuki
2012-11-02 6:28 ` Wen Congyang
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