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    SubjectRe: memory_hotplug: always initialize pageblock bitmap.
    On Tue, May 13, 2008 at 01:58:25PM +0200, Heiko Carstens wrote:
    > From: Heiko Carstens <>
    > 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. That means that get_pageblock_migratetype() returns
    > also random stuff and therefore
    > list_add(&page->lru,
    > &zone->free_area[order].free_list[migratetype]);
    > in __free_one_page() tries to do a list_add to something that isn't even
    > necessarily a list.
    > This happens since 86051ca5eaf5e560113ec7673462804c54284456
    > ("mm: fix usemap initialization") which makes sure that the pageblock
    > bitmap gets only initialized for pages present in a zone.
    > Unfortunately for hot-added memory the zones "grow" after the memmap
    > and the pageblock memmap have been initialized. Which means that the
    > new pages have an unitialized bitmap.
    > To solve this the calls to grow_zone_span() and grow_pgdat_span() are
    > moved to __add_zone() just before the initialization happens.
    > The patch also moves the two functions since __add_zone() is the only
    > caller and I didn't want to add a forward declaration.
    > Signed-off-by: Heiko Carstens <>
    > Cc: Andy Whitcroft <>
    > Cc: Dave Hansen <>
    > Cc: Gerald Schaefer <>
    > Cc: KAMEZAWA Hiroyuki <>
    > Cc: Yasunori Goto <>
    > Signed-off-by: Andrew Morton <>
    > ---

    Oops... the patch is tested and works for me. However it was not Signed-off
    by Andrew. And in addition I forgot to add [PATCH] to the subject.
    Sorry about that!

    If all agree that this patch is ok it should probably also go into
    -stable, since it fixes the above mentioned regression.

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      Last update: 2008-05-13 20:55    [W:0.022 / U:8.508 seconds]
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