• Adam Litke's avatar
    hugetlb: correct page count for surplus huge pages · 2668db91
    Adam Litke authored
    
    
    Free pages in the hugetlb pool are free and as such have a reference count of
    zero.  Regular allocations into the pool from the buddy are "freed" into the
    pool which results in their page_count dropping to zero.  However, surplus
    pages can be directly utilized by the caller without first being freed to the
    pool.  Therefore, a call to put_page_testzero() is in order so that such a
    page will be handed to the caller with a correct count.
    
    This has not affected end users because the bad page count is reset before the
    page is handed off.  However, under CONFIG_DEBUG_VM this triggers a BUG when
    the page count is validated.
    
    Thanks go to Mel for first spotting this issue and providing an initial fix.
    Signed-off-by: default avatarAdam Litke <agl@us.ibm.com>
    Cc: Mel Gorman <mel@csn.ul.ie>
    Cc: Dave Hansen <haveblue@us.ibm.com>
    Cc: William Lee Irwin III <wli@holomorphy.com>
    Cc: Andy Whitcroft <apw@shadowen.org>
    Cc: Mel Gorman <mel@csn.ul.ie>
    Cc: David Gibson <david@gibson.dropbear.id.au>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    2668db91