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mm/hugetlb: check gigantic_page_runtime_supported() in return_unused_…
…surplus_pages() Patch series "mm, hwpoison: enable 1GB hugepage support", v7. This patch (of 8): I found a weird state of 1GB hugepage pool, caused by the following procedure: - run a process reserving all free 1GB hugepages, - shrink free 1GB hugepage pool to zero (i.e. writing 0 to /sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages), then - kill the reserving process. , then all the hugepages are free *and* surplus at the same time. $ cat /sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages 3 $ cat /sys/kernel/mm/hugepages/hugepages-1048576kB/free_hugepages 3 $ cat /sys/kernel/mm/hugepages/hugepages-1048576kB/resv_hugepages 0 $ cat /sys/kernel/mm/hugepages/hugepages-1048576kB/surplus_hugepages 3 This state is resolved by reserving and allocating the pages then freeing them again, so this seems not to result in serious problem. But it's a little surprising (shrinking pool suddenly fails). This behavior is caused by hstate_is_gigantic() check in return_unused_surplus_pages(). This was introduced so long ago in 2008 by commit aa888a7 ("hugetlb: support larger than MAX_ORDER"), and at that time the gigantic pages were not supposed to be allocated/freed at run-time. Now kernel can support runtime allocation/free, so let's check gigantic_page_runtime_supported() together. Link: https://lkml.kernel.org/r/[email protected] Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Naoya Horiguchi <[email protected]> Reviewed-by: Miaohe Lin <[email protected]> Cc: David Hildenbrand <[email protected]> Cc: Mike Kravetz <[email protected]> Cc: Liu Shixin <[email protected]> Cc: Yang Shi <[email protected]> Cc: Oscar Salvador <[email protected]> Cc: Muchun Song <[email protected]> Cc: kernel test robot <[email protected]> Signed-off-by: Andrew Morton <[email protected]>
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