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[S390] vmemmap: allocate struct pages before 1:1 mapping

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We have seen an oops in an OOM situation, where show_mem tried to
access the struct page of a dcss segment. The vmemmap code has
already created the 1:1 mapping but failed allocating the struct
pages. In the OOM case, show_mem now walks the memory. It uses
pfn_valid to detect if it may access the struct page. In the case
described above, the mapping was established and pfn_valid returned
true. As the struct pages were not allocated, the kernel oopsed.

We have to ensure that we have created the struct pages, before we
add a mapping pointing to the pages.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Christian Borntraeger 2008-01-26 14:11:16 +01:00 committed by Martin Schwidefsky
parent d09293aee9
commit a2fd64d6aa
1 changed files with 2 additions and 2 deletions
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4
arch/s390/mm/vmem.c
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@ -236,10 +236,10 @@ static int vmem_add_mem(unsigned long start, unsigned long size)
{
int ret;
ret = vmem_add_range(start, size);
ret = vmem_add_mem_map(start, size);
if (ret)
return ret;
return vmem_add_mem_map(start, size);
return vmem_add_range(start, size);
}
/*