From: Andrew Morton <akpm@linux-foundation.org>
To: Minchan Kim <minchan@kernel.org>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Subject: Re: [PATCH v3] memory-hotplug: fix zone stat mismatch
Date: Thu, 20 Sep 2012 14:42:32 -0700 [thread overview]
Message-ID: <20120920144232.a3e8b60f.akpm@linux-foundation.org> (raw)
In-Reply-To: <1348123405-30641-1-git-send-email-minchan@kernel.org>
On Thu, 20 Sep 2012 15:43:25 +0900
Minchan Kim <minchan@kernel.org> wrote:
> During memory-hotplug, I found NR_ISOLATED_[ANON|FILE]
> are increasing so that kernel are hang out.
>
> The cause is that when we do memory-hotadd after memory-remove,
> __zone_pcp_update clear out zone's ZONE_STAT_ITEMS in setup_pageset
> although vm_stat_diff of all CPU still have value.
>
> In addtion, when we offline all pages of the zone, we reset them
> in zone_pcp_reset without drain so that we lost zone stat item.
>
Here's what I ended up with for a changelog:
: During memory-hotplug, I found NR_ISOLATED_[ANON|FILE] are increasing,
: causing the kernel to hang. When the system doesn't have enough free
: pages, it enters reclaim but never reclaim any pages due to
: too_many_isolated()==true and loops forever.
:
: The cause is that when we do memory-hotadd after memory-remove,
: __zone_pcp_update() clears a zone's ZONE_STAT_ITEMS in setup_pageset()
: although the vm_stat_diff of all CPUs still have values.
:
: In addtion, when we offline all pages of the zone, we reset them in
: zone_pcp_reset without draining so we loss some zone stat item.
As memory hotplug seems fairly immature and broken, I'm thinking
there's no point in backporting this into -stable. And I don't *think*
we really need it in 3.6 either? (It doesn't apply cleanly to current
mainline anyway - I didn't check why).
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next prev parent reply other threads:[~2012-09-20 21:42 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-20 6:43 [PATCH v3] memory-hotplug: fix zone stat mismatch Minchan Kim
2012-09-20 7:21 ` Yasuaki Ishimatsu
2012-09-20 7:37 ` Minchan Kim
2012-09-20 21:42 ` Andrew Morton [this message]
2012-09-20 23:36 ` Minchan Kim
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