On 02/02/2016 07:01 PM, Naoya Horiguchi wrote:
> On Tue, Feb 02, 2016 at 03:17:10PM -0800, Mike Kravetz wrote:
>> I agree. Naoya did debug and provide fix via e-mail exchange. He did not
>> sign-off and I could not tell if he was going to pursue. My only intention
>> was to fix ASAP.
>>
>> More than happy to give Naoya credit.
>
> Thank you! It's great if you append my signed-off below yours.
>
> Naoya
Adding Naoya's sign off and Acks received
mm/hugetlb: fix gigantic page initialization/allocation
Attempting to preallocate 1G gigantic huge pages at boot time with
"hugepagesz=1G hugepages=1" on the kernel command line will prevent
booting with the following:
kernel BUG at mm/hugetlb.c:1218!
When mapcount accounting was reworked, the setting of compound_mapcount_ptr
in prep_compound_gigantic_page was overlooked. As a result, the validation
of mapcount in free_huge_page fails.
The "BUG_ON" checks in free_huge_page were also changed to "VM_BUG_ON_PAGE"
to assist with debugging.
Fixes: af5642a8af ("mm: rework mapcount accounting to enable 4k mapping
of THPs")
Signed-off-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Signed-off-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Acked-by: David Rientjes <rientjes@xxxxxxxxxx>
---
mm/hugetlb.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 12908dc..d7a8024 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1214,8 +1214,8 @@ void free_huge_page(struct page *page)
set_page_private(page, 0);
page->mapping = NULL;
- BUG_ON(page_count(page));
- BUG_ON(page_mapcount(page));
+ VM_BUG_ON_PAGE(page_count(page), page);
+ VM_BUG_ON_PAGE(page_mapcount(page), page);
restore_reserve = PagePrivate(page);
ClearPagePrivate(page);
@@ -1286,6 +1286,7 @@ static void prep_compound_gigantic_page(struct
page *page, unsigned int order)
set_page_count(p, 0);
set_compound_head(p, page);
}
+ atomic_set(compound_mapcount_ptr(page), -1);
}
/*
--
2.4.3
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