ARM: mm: Split memory banks that span multiple sections when sparsemem is enabled

This fixes a crash in mem_init which assumes all pages in a memory bank
are part of the same page array.

Signed-off-by: Arve Hjønnevåg <arve@android.com>

diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index d11e7b569e37165b049a68121feb4742f187a767..cc9c66694f342bea481a56d7ee5803799e6c4fc6 100644 (file)
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -1017,6 +1017,28 @@ void __init sanity_check_meminfo(void)
                struct membank *bank = &meminfo.bank[j];
                *bank = meminfo.bank[i];
 
+#ifdef CONFIG_SPARSEMEM
+               if (pfn_to_section_nr(bank_pfn_start(bank)) !=
+                   pfn_to_section_nr(bank_pfn_end(bank) - 1)) {
+                       phys_addr_t sz;
+                       unsigned long start_pfn = bank_pfn_start(bank);
+                       unsigned long end_pfn = SECTION_ALIGN_UP(start_pfn + 1);
+                       sz = ((phys_addr_t)(end_pfn - start_pfn) << PAGE_SHIFT);
+
+                       if (meminfo.nr_banks >= NR_BANKS) {
+                               pr_crit("NR_BANKS too low, ignoring %lld bytes of memory\n",
+                                       (unsigned long long)(bank->size - sz));
+                       } else {
+                               memmove(bank + 1, bank,
+                                       (meminfo.nr_banks - i) * sizeof(*bank));
+                               meminfo.nr_banks++;
+                               bank[1].size -= sz;
+                               bank[1].start = __pfn_to_phys(end_pfn);
+                       }
+                       bank->size = sz;
+               }
+#endif
+
                if (bank->start > ULONG_MAX)
                        highmem = 1;