Commit a2fd64d6 authored Jan 26, 2008 by Christian Borntraeger Committed by Martin Schwidefsky Jan 26, 2008

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



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>

parent d09293ae

arch/s390/mm/vmem.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -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);
		}

		/*