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SubjectRe: [PATCH] hugetlbfs: Call VM_BUG_ON_PAGE earlier in free_huge_page
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On 11/29/18 5:51 AM, William Kucharski wrote:
> Reviewed-by: William Kucharski <william.kucharski@oracle.com>
>
>> On Nov 29, 2018, at 4:44 AM, Yongkai Wu <nic.wuyk@gmail.com> wrote:
>>
>> A stack trace was triggered by VM_BUG_ON_PAGE(page_mapcount(page),
>> page) in free_huge_page(). Unfortunately, the page->mapping field
>> was set to NULL before this test. This made it more difficult to
>> determine the root cause of the problem.
>>
>> Move the VM_BUG_ON_PAGE tests earlier in the function so that if
>> they do trigger more information is present in the page struct.
>>
>> Signed-off-by: Yongkai Wu <nic_w@163.com>
>> Acked-by: Michal Hocko <mhocko@suse.com>
>> Acked-by: Mike Kravetz <mike.kravetz@oracle.com>

Thank you for fixing the formatting and commit message.

Adding Andrew on so he can add to his tree as appropriatre. Also Cc'ing Michal.

>> ---
>> mm/hugetlb.c | 5 +++--
>> 1 file changed, 3 insertions(+), 2 deletions(-)
>>
>> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
>> index 7f2a28a..14ef274 100644
>> --- a/mm/hugetlb.c
>> +++ b/mm/hugetlb.c
>> @@ -1248,10 +1248,11 @@ void free_huge_page(struct page *page)
>> (struct hugepage_subpool *)page_private(page);
>> bool restore_reserve;
>>
>> - set_page_private(page, 0);
>> - page->mapping = NULL;
>> VM_BUG_ON_PAGE(page_count(page), page);
>> VM_BUG_ON_PAGE(page_mapcount(page), page);
>> +
>> + set_page_private(page, 0);
>> + page->mapping = NULL;
>> restore_reserve = PagePrivate(page);
>> ClearPagePrivate(page);
>>
>> --
>> 1.8.3.1
>>
>


--
Mike Kravetz

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