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| author |   Naoya Horiguchi <naoya.horiguchi@nec.com> | 2022-07-14 13:24:13 +0900 |
|---|---|---|
| committer |   Andrew Morton <akpm@linux-foundation.org> | 2022-08-08 18:06:43 -0700 |
| commit | c0531714d6e3fd720b7dacc2de2d0503a995bcdc (patch) | |
| tree | 2eb6bcba208d42e396e402dee9ccd7b167938965 /mm/hugetlb.c | |
| parent | mm: hugetlb_vmemmap: use PTRS_PER_PTE instead of PMD_SIZE / PAGE_SIZE (diff) | |
| download | linux-dev-c0531714d6e3fd720b7dacc2de2d0503a995bcdc.tar.xz linux-dev-c0531714d6e3fd720b7dacc2de2d0503a995bcdc.zip | |
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 aa888a74977a ("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/20220714042420.1847125-1-naoya.horiguchi@linux.dev
Link: https://lkml.kernel.org/r/20220714042420.1847125-2-naoya.horiguchi@linux.dev
Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Liu Shixin <liushixin2@huawei.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: kernel test robot <lkp@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/hugetlb.c')
| -rw-r--r-- | mm/hugetlb.c | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 598c37279fee..ee6655e47213 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -2432,8 +2432,7 @@ static void return_unused_surplus_pages(struct hstate *h, /* Uncommit the reservation */ h->resv_huge_pages -= unused_resv_pages; - /* Cannot return gigantic pages currently */ - if (hstate_is_gigantic(h)) + if (hstate_is_gigantic(h) && !gigantic_page_runtime_supported()) goto out; /* |