Commit cc81717e authored by Michal Hocko's avatar Michal Hocko Committed by Linus Torvalds

mm: new_vma_page() cannot see NULL vma for hugetlb pages

Commit 11c731e8 ("mm/mempolicy: fix !vma in new_vma_page()") has
removed BUG_ON(!vma) from new_vma_page which is partially correct
because page_address_in_vma will return EFAULT for non-linear mappings
and at least shared shmem might be mapped this way.

The patch also tried to prevent NULL ptr for hugetlb pages which is not
correct AFAICS because hugetlb pages cannot be mapped as VM_NONLINEAR
and other conditions in page_address_in_vma seem to be legit and catch
real bugs.

This patch restores BUG_ON for PageHuge to catch potential issues when
the to-be-migrated page is not setup properly.
Signed-off-by: default avatarMichal Hocko <mhocko@suse.cz>
Reviewed-by: default avatarBob Liu <bob.liu@oracle.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 54b9dd14
......@@ -1199,10 +1199,8 @@ static struct page *new_vma_page(struct page *page, unsigned long private, int *
}
if (PageHuge(page)) {
if (vma)
BUG_ON(!vma);
return alloc_huge_page_noerr(vma, address, 1);
else
return NULL;
}
/*
* if !vma, alloc_page_vma() will use task or system default policy
......
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