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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; } } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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