linux-kernel - Re: [PATCH] mm/page_alloc: don't re-init pageset in zone_pcp

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Message-Id: <20130612142032.882a28b7911ed24ca19e282e@linux-foundation.org>
Date:	Wed, 12 Jun 2013 14:20:32 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Cody P Schafer <cody@...ux.vnet.ibm.com>
Cc:	LKML <linux-kernel@...r.kernel.org>, Linux MM <linux-mm@...ck.org>,
	Valdis.Kletnieks@...edu
Subject: Re: [PATCH] mm/page_alloc: don't re-init pageset in
 zone_pcp_update()

On Tue, 11 Jun 2013 15:12:59 -0700 Cody P Schafer <cody@...ux.vnet.ibm.com> wrote:

> Factor pageset_set_high_and_batch() (which contains all needed logic too
> set a pageset's ->high and ->batch inrespective of system state) out of
> zone_pageset_init(), which avoids us calling pageset_init(), and
> unsafely blowing away a pageset at runtime (leaked pages and
> potentially some funky allocations would be the result) when memory
> hotplug is triggered.

This changelog is pretty screwed up :( It tells us what the patch does
but not why it does it.

> Signed-off-by: Cody P Schafer <cody@...ux.vnet.ibm.com>
> ---
> 
> Unless memory hotplug is being triggered on boot, this should *not* be cause of Valdis
> Kletnieks' reported bug in -next:
>          "next-20130607 BUG: Bad page state in process systemd pfn:127643"

And this addendum appears to hint at the info we need.

Please, send a new changelog?  That should include a description of the
user-visible effects of the bug which is being fixed, a description of
why it occurs and a description of how it was fixed.  It would also be
helpful if you can identify which kernel version(s) need the fix.

Also, a Reported-by:Valdis would be appropriate.

Thanks.
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