[SPARC64]: Document and fix calculation of pages_avail.
It should be set to the total number of pages that the
system will really have available after things like
initmem, the bootmem map, and initrd are freed up.
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/arch/sparc64/mm/init.c b/arch/sparc64/mm/init.c
index 4027618..cafadcb 100644
--- a/arch/sparc64/mm/init.c
+++ b/arch/sparc64/mm/init.c
@@ -938,6 +938,20 @@
}
}
+/* About pages_avail, this is the value we will use to calculate
+ * the zholes_size[] argument given to free_area_init_node(). The
+ * page allocator uses this to calculate nr_kernel_pages,
+ * nr_all_pages and zone->present_pages. On NUMA it is used
+ * to calculate zone->min_unmapped_pages and zone->min_slab_pages.
+ *
+ * So this number should really be set to what the page allocator
+ * actually ends up with. This means:
+ * 1) It should include bootmem map pages, we'll release those.
+ * 2) It should not include the kernel image, except for the
+ * __init sections which we will also release.
+ * 3) It should include the initrd image, since we'll release
+ * that too.
+ */
static unsigned long __init bootmem_init(unsigned long *pages_avail,
unsigned long phys_base)
{
@@ -1024,7 +1038,6 @@
initrd_start, initrd_end);
#endif
reserve_bootmem(initrd_start, size);
- *pages_avail -= PAGE_ALIGN(size) >> PAGE_SHIFT;
initrd_start += PAGE_OFFSET;
initrd_end += PAGE_OFFSET;
@@ -1037,6 +1050,11 @@
reserve_bootmem(kern_base, kern_size);
*pages_avail -= PAGE_ALIGN(kern_size) >> PAGE_SHIFT;
+ /* Add back in the initmem pages. */
+ size = ((unsigned long)(__init_end) & PAGE_MASK) -
+ PAGE_ALIGN((unsigned long)__init_begin);
+ *pages_avail += size >> PAGE_SHIFT;
+
/* Reserve the bootmem map. We do not account for it
* in pages_avail because we will release that memory
* in free_all_bootmem.
@@ -1047,7 +1065,6 @@
(bootmap_pfn << PAGE_SHIFT), size);
#endif
reserve_bootmem((bootmap_pfn << PAGE_SHIFT), size);
- *pages_avail -= PAGE_ALIGN(size) >> PAGE_SHIFT;
for (i = 0; i < pavail_ents; i++) {
unsigned long start_pfn, end_pfn;
@@ -1539,6 +1556,10 @@
#ifdef CONFIG_DEBUG_BOOTMEM
prom_printf("mem_init: Calling free_all_bootmem().\n");
#endif
+
+ /* We subtract one to account for the mem_map_zero page
+ * allocated below.
+ */
totalram_pages = num_physpages = free_all_bootmem() - 1;
/*