Messages in this thread | | | Date | Wed, 5 Nov 2014 10:17:34 +0800 | From | Tang Chen <> | Subject | Re: [PATCH 2/2] mem-hotplug: Fix wrong check for zone->pageset initialization in online_pages(). |
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On 11/05/2014 09:01 AM, Kamezawa Hiroyuki wrote: > ...... > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index 3ab01b2..bc0de0f 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -1013,9 +1013,13 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages, int online_typ > * If this zone is not populated, then it is not in zonelist. > * This means the page allocator ignores this zone. > * So, zonelist must be updated after online. > + * > + * If this zone is populated, zone->pageset could be initialized > + * to boot_pageset for the first time a node is added. If so, > + * zone->pageset should be allocated. > */ > mutex_lock(&zonelists_mutex); > - if (!populated_zone(zone)) { > + if (!populated_zone(zone) || !zone_pcp_initialized(zone)) { > Please don't add another strange meanings to zone's pcplist. > > If you say zone->present_pages doesn't mean zone has pages in buddy list any more, > please rewrite all parts using zone->present_pages including populated_zone().
Adding Liu Jiang...
I think zone->managed_pages was introduced by Liu Jiang in the following patch:
From 9feedc9d831e18ae6d0d15aa562e5e46ba53647b Mon Sep 17 00:00:00 2001 From: Jiang Liu <liuj97@gmail.com> Date: Wed, 12 Dec 2012 13:52:12 -0800 Subject: [PATCH 1/1] mm: introduce new field "managed_pages" to struct zone
Before this patch, zone->present_pages meant "amount of memory (excluding holes)", not the zone has pages in buddy system.
So I think zone->present_pages keeps its meaning as before. But it may be abused somewhere else, such as here.
> I think there are several parts calculates parameters based on present_pages. > > I myself doesn't welcome having both of compliated "managed pages" and "present pages"... > > How about adding > > static inline int managed_zone(struct zone *zone) > { > return (!!zone->managed_pages); > } > > for this bug fix ?
Yes, adding this function could fix this problem.
And by the way, we have the following code in onine_pages():
zone->present_pages += onlined_pages;
pgdat_resize_lock(zone->zone_pgdat, &flags); zone->zone_pgdat->node_present_pages += onlined_pages; pgdat_resize_unlock(zone->zone_pgdat, &flags);
We should do this when the zone size is changed, not where it is now. Will send patches for this soon.
Thanks.
> > Other parts, using present_pages, should be considered well. > >
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