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Message-ID: <20080510124501.GA4796@osiris.boeblingen.de.ibm.com>
Date: Sat, 10 May 2008 14:45:01 +0200
From: Heiko Carstens <heiko.carstens@...ibm.com>
To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
Andy Whitcroft <apw@...dowen.org>,
Dave Hansen <haveblue@...ibm.com>,
Gerald Schaefer <gerald.schaefer@...ibm.com>,
linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH] memory_hotplug: always initialize pageblock bitmap.
On Fri, May 09, 2008 at 03:39:10PM +0900, KAMEZAWA Hiroyuki wrote:
> On Fri, 9 May 2008 08:06:09 +0200
> Heiko Carstens <heiko.carstens@...ibm.com> wrote:
>
> > From: Heiko Carstens <heiko.carstens@...ibm.com>
> >
> > Trying to online a new memory section that was added via memory hotplug
> > sometimes results in crashes when the new pages are added via
> > __free_page. Reason for that is that the pageblock bitmap isn't
> > initialized and hence contains random stuff.
>
> Hmm, curious. In my understanding, memmap_init_zone() initializes it.
>
> __add_pages()
> -> __add_section()
> -> sparse-add_one_section() // allocate usemap
> -> __add_zone()
> -> memmap_init_zone() // reset pageblock's bitmap
>
> Can't memmap_init_zone() does proper initialization ?
> ........................
> Ah, ok. I see. grow_zone_span() is not called at __add_zone(), then,
> memmap_init_zone() doesn't initialize usemap because memmap is not in zone's
> range.
Now I got it. So my patch was incorrect, it just worked around the crash.
> Recently, I added a check "zone's start_pfn < pfn < zone's end"
> to memmap_init_zone()'s usemap initialization for !SPARSEMEM case bug FIX.
> (and I think the fix itself is sane.)
Oh, you broke memory hot-add on -stable ;)
> How about calling grow_pgdat_span()/grow_zone_span() from __add_zone() ?
Like this?
Note that this patch is on top of the other patch I already sent, but
reverts it...
This works for me. A final version (if this is acceptable) should move
the grow* functions also.
---
mm/memory_hotplug.c | 28 +++++++++++++++++++---------
mm/page_alloc.c | 3 +--
2 files changed, 20 insertions(+), 11 deletions(-)
Index: linux-2.6/mm/memory_hotplug.c
===================================================================
--- linux-2.6.orig/mm/memory_hotplug.c
+++ linux-2.6/mm/memory_hotplug.c
@@ -159,17 +159,33 @@ void register_page_bootmem_info_node(str
}
#endif /* !CONFIG_SPARSEMEM_VMEMMAP */
+static void grow_zone_span(struct zone *zone, unsigned long start_pfn,
+ unsigned long end_pfn);
+static void grow_pgdat_span(struct pglist_data *pgdat,
+ unsigned long start_pfn, unsigned long end_pfn);
+
static int __add_zone(struct zone *zone, unsigned long phys_start_pfn)
{
struct pglist_data *pgdat = zone->zone_pgdat;
int nr_pages = PAGES_PER_SECTION;
int nid = pgdat->node_id;
int zone_type;
+ unsigned long flags;
zone_type = zone - pgdat->node_zones;
- if (!zone->wait_table)
- return init_currently_empty_zone(zone, phys_start_pfn,
- nr_pages, MEMMAP_HOTPLUG);
+ if (!zone->wait_table) {
+ int ret;
+
+ ret = init_currently_empty_zone(zone, phys_start_pfn,
+ nr_pages, MEMMAP_HOTPLUG);
+ if (ret)
+ return ret;
+ }
+ pgdat_resize_lock(zone->zone_pgdat, &flags);
+ grow_zone_span(zone, phys_start_pfn, phys_start_pfn + nr_pages);
+ grow_pgdat_span(zone->zone_pgdat, phys_start_pfn,
+ phys_start_pfn + nr_pages);
+ pgdat_resize_unlock(zone->zone_pgdat, &flags);
memmap_init_zone(nr_pages, nid, zone_type,
phys_start_pfn, MEMMAP_HOTPLUG);
return 0;
@@ -363,7 +379,6 @@ static int online_pages_range(unsigned l
int online_pages(unsigned long pfn, unsigned long nr_pages)
{
- unsigned long flags;
unsigned long onlined_pages = 0;
struct zone *zone;
int need_zonelists_rebuild = 0;
@@ -391,11 +406,6 @@ int online_pages(unsigned long pfn, unsi
* memory_block->state_mutex.
*/
zone = page_zone(pfn_to_page(pfn));
- pgdat_resize_lock(zone->zone_pgdat, &flags);
- grow_zone_span(zone, pfn, pfn + nr_pages);
- grow_pgdat_span(zone->zone_pgdat, pfn, pfn + nr_pages);
- pgdat_resize_unlock(zone->zone_pgdat, &flags);
-
/*
* If this zone is not populated, then it is not in zonelist.
* This means the page allocator ignores this zone.
Index: linux-2.6/mm/page_alloc.c
===================================================================
--- linux-2.6.orig/mm/page_alloc.c
+++ linux-2.6/mm/page_alloc.c
@@ -2862,8 +2862,6 @@ __meminit int init_currently_empty_zone(
zone->zone_start_pfn = zone_start_pfn;
- memmap_init(size, pgdat->node_id, zone_idx(zone), zone_start_pfn);
-
zone_init_free_lists(zone);
return 0;
@@ -3433,6 +3431,7 @@ static void __paginginit free_area_init_
ret = init_currently_empty_zone(zone, zone_start_pfn,
size, MEMMAP_EARLY);
BUG_ON(ret);
+ memmap_init(size, nid, j, zone_start_pfn);
zone_start_pfn += size;
}
}
--
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