1 files changed, 38 insertions, 5 deletions

diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index 4f56617a2392..b3fdb63783e3 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -989,6 +989,7 @@ phys_addr_t arm_lowmem_limit __initdata = 0;
 
 void __init sanity_check_meminfo(void)
 {
+        phys_addr_t memblock_limit = 0;
         int i, j, highmem = 0;
         phys_addr_t vmalloc_limit = __pa(vmalloc_min - 1) + 1;
 
@@ -1052,9 +1053,32 @@ void __init sanity_check_meminfo(void)
                         bank->size = size_limit;
                 }
 #endif
-                if (!bank->highmem && bank->start + bank->size > arm_lowmem_limit)
-                        arm_lowmem_limit = bank->start + bank->size;
+                if (!bank->highmem) {
+                        phys_addr_t bank_end = bank->start + bank->size;
 
+                        if (bank_end > arm_lowmem_limit)
+                                arm_lowmem_limit = bank_end;
+
+                        /*
+                         * Find the first non-section-aligned page, and point
+                         * memblock_limit at it. This relies on rounding the
+                         * limit down to be section-aligned, which happens at
+                         * the end of this function.
+                         *
+                         * With this algorithm, the start or end of almost any
+                         * bank can be non-section-aligned. The only exception
+                         * is that the start of the bank 0 must be section-
+                         * aligned, since otherwise memory would need to be
+                         * allocated when mapping the start of bank 0, which
+                         * occurs before any free memory is mapped.
+                         */
+                        if (!memblock_limit) {
+                                if (!IS_ALIGNED(bank->start, SECTION_SIZE))
+                                        memblock_limit = bank->start;
+                                else if (!IS_ALIGNED(bank_end, SECTION_SIZE))
+                                        memblock_limit = bank_end;
+                        }
+                }
                 j++;
         }
 #ifdef CONFIG_HIGHMEM
@@ -1079,7 +1103,18 @@ void __init sanity_check_meminfo(void)
 #endif
         meminfo.nr_banks = j;
         high_memory = __va(arm_lowmem_limit - 1) + 1;
-        memblock_set_current_limit(arm_lowmem_limit);
+
+        /*
+         * Round the memblock limit down to a section size.  This
+         * helps to ensure that we will allocate memory from the
+         * last full section, which should be mapped.
+         */
+        if (memblock_limit)
+                memblock_limit = round_down(memblock_limit, SECTION_SIZE);
+        if (!memblock_limit)
+                memblock_limit = arm_lowmem_limit;
+
+        memblock_set_current_limit(memblock_limit);
 }
 
 static inline void prepare_page_table(void)
@@ -1276,8 +1311,6 @@ void __init paging_init(struct machine_desc *mdesc)
 {
         void *zero_page;
 
-        memblock_set_current_limit(arm_lowmem_limit);
-
         build_mem_type_table();
         prepare_page_table();
         map_lowmem();