mm: make defensive checks around PFN values registered for memory usage

[safe/jmp/linux-2.6] / mm / sparse.c

diff --git a/mm/sparse.c b/mm/sparse.c
index 36511c7..7a36509 100644 (file)
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -12,6 +12,7 @@
 #include <asm/dma.h>
 #include <asm/pgalloc.h>
 #include <asm/pgtable.h>
+#include "internal.h"
 
 /*
  * Permanent SPARSEMEM data:
@@ -147,22 +148,41 @@ static inline int sparse_early_nid(struct mem_section *section)
        return (section->section_mem_map >> SECTION_NID_SHIFT);
 }
 
-/* Record a memory area against a node. */
-void __init memory_present(int nid, unsigned long start, unsigned long end)
+/* Validate the physical addressing limitations of the model */
+void __meminit mminit_validate_memmodel_limits(unsigned long *start_pfn,
+                                               unsigned long *end_pfn)
 {
-       unsigned long max_arch_pfn = 1UL << (MAX_PHYSMEM_BITS-PAGE_SHIFT);
-       unsigned long pfn;
+       unsigned long max_sparsemem_pfn = 1UL << (MAX_PHYSMEM_BITS-PAGE_SHIFT);
 
        /*
         * Sanity checks - do not allow an architecture to pass
         * in larger pfns than the maximum scope of sparsemem:
         */
-       if (start >= max_arch_pfn)
-               return;
-       if (end >= max_arch_pfn)
-               end = max_arch_pfn;
+       if (*start_pfn > max_sparsemem_pfn) {
+               mminit_dprintk(MMINIT_WARNING, "pfnvalidation",
+                       "Start of range %lu -> %lu exceeds SPARSEMEM max %lu\n",
+                       *start_pfn, *end_pfn, max_sparsemem_pfn);
+               WARN_ON_ONCE(1);
+               *start_pfn = max_sparsemem_pfn;
+               *end_pfn = max_sparsemem_pfn;
+       }
+
+       if (*end_pfn > max_sparsemem_pfn) {
+               mminit_dprintk(MMINIT_WARNING, "pfnvalidation",
+                       "End of range %lu -> %lu exceeds SPARSEMEM max %lu\n",
+                       *start_pfn, *end_pfn, max_sparsemem_pfn);
+               WARN_ON_ONCE(1);
+               *end_pfn = max_sparsemem_pfn;
+       }
+}
+
+/* Record a memory area against a node. */
+void __init memory_present(int nid, unsigned long start, unsigned long end)
+{
+       unsigned long pfn;
 
        start &= PAGE_SECTION_MASK;
+       mminit_validate_memmodel_limits(&start, &end);
        for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION) {
                unsigned long section = pfn_to_section_nr(pfn);
                struct mem_section *ms;
@@ -187,6 +207,7 @@ unsigned long __init node_memmap_size_bytes(int nid, unsigned long start_pfn,
        unsigned long pfn;
        unsigned long nr_pages = 0;
 
+       mminit_validate_memmodel_limits(&start_pfn, &end_pfn);
        for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
                if (nid != early_pfn_to_nid(pfn))
                        continue;