[PATCH] [24/31] CPA: Only unmap kernel init pages in text mapping when CONFIG_DEBUG_RODATA is set

Andi Kleen
2008-01-14T22:25:36Z

Otherwise the kernel will likely always run with 4K pages instead of 2MB pages,
which is costly in terms of TLBs.

Also optimize it a little bit by using only a single change_page_attr() calls.
This is particularly useful if debugging is enabled inside it because it spams
the logs much less.

Signed-off-by: Andi Kleen <ak@suse.de>

---
arch/x86/mm/init_64.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)

Index: linux/arch/x86/mm/init_64.c
===================================================================
--- linux.orig/arch/x86/mm/init_64.c
+++ linux/arch/x86/mm/init_64.c
@@ -553,13 +553,16 @@ void free_init_pages(char *what, unsigne
init_page_count(virt_to_page(addr));
memset((void *)(addr & ~(PAGE_SIZE-1)),
POISON_FREE_INITMEM, PAGE_SIZE);
- if (addr >= __START_KERNEL_map)
- change_page_attr_addr(addr, 1, __pgprot(0));
free_page(addr);
totalram_pages++;
}
- if (addr > __START_KERNEL_map)
+#ifdef CONFIG_DEBUG_RODATA
+ if (begin >= __START_KERNEL_map) {
+ change_page_attr_addr(begin, (end - begin)/PAGE_SIZE,
+ __pgprot(0));
global_flush_tlb();
+ }
+#endif
}

void free_initmem(void)