Re: [PATCH] mm/page_alloc: don't re-init pageset inzone_pcp_update()

From: Andrew Morton
Date: Wed Jun 12 2013 - 17:20:39 EST


On Tue, 11 Jun 2013 15:12:59 -0700 Cody P Schafer <cody@xxxxxxxxxxxxxxxxxx> 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@xxxxxxxxxxxxxxxxxx>
> ---
>
> 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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