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Subject[PATCH] [225/275] x86: Cleanup highmap after brk is concluded
Date
2.6.35-longterm review patch.  If anyone has any objections, please let me know.

------------------
From: Yinghai Lu <yinghai@kernel.org>

commit e5f15b45ddf3afa2bbbb10c7ea34fb32b6de0a0e upstream.

Now cleanup_highmap actually is in two steps: one is early in head64.c
and only clears above _end; a second one is in init_memory_mapping() and
tries to clean from _brk_end to _end.
It should check if those boundaries are PMD_SIZE aligned but currently
does not.
Also init_memory_mapping() is called several times for numa or memory
hotplug, so we really should not handle initial kernel mappings there.

This patch moves cleanup_highmap() down after _brk_end is settled so
we can do everything in one step.
Also we honor max_pfn_mapped in the implementation of cleanup_highmap.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
LKML-Reference: <alpine.DEB.2.00.1103171739050.3382@kaball-desktop>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
arch/x86/kernel/head64.c | 3 ---
arch/x86/kernel/setup.c | 5 +++++
arch/x86/mm/init.c | 19 -------------------
arch/x86/mm/init_64.c | 11 ++++++-----
4 files changed, 11 insertions(+), 27 deletions(-)

Index: linux-2.6.35.y/arch/x86/kernel/head64.c
===================================================================
--- linux-2.6.35.y.orig/arch/x86/kernel/head64.c 2011-03-29 22:50:26.228587294 -0700
+++ linux-2.6.35.y/arch/x86/kernel/head64.c 2011-03-29 23:03:02.918225501 -0700
@@ -76,9 +76,6 @@
/* Make NULL pointers segfault */
zap_identity_mappings();

- /* Cleanup the over mapped high alias */
- cleanup_highmap();
-
for (i = 0; i < NUM_EXCEPTION_VECTORS; i++) {
#ifdef CONFIG_EARLY_PRINTK
set_intr_gate(i, &early_idt_handlers[i]);
Index: linux-2.6.35.y/arch/x86/kernel/setup.c
===================================================================
--- linux-2.6.35.y.orig/arch/x86/kernel/setup.c 2011-03-29 22:50:26.228587294 -0700
+++ linux-2.6.35.y/arch/x86/kernel/setup.c 2011-03-29 23:03:02.918225501 -0700
@@ -296,6 +296,9 @@
static inline void init_gbpages(void)
{
}
+static void __init cleanup_highmap(void)
+{
+}
#endif

static void __init reserve_brk(void)
@@ -926,6 +929,8 @@

reserve_brk();

+ cleanup_highmap();
+
/*
* Find and reserve possible boot-time SMP configuration:
*/
Index: linux-2.6.35.y/arch/x86/mm/init.c
===================================================================
--- linux-2.6.35.y.orig/arch/x86/mm/init.c 2011-03-29 22:50:26.228587294 -0700
+++ linux-2.6.35.y/arch/x86/mm/init.c 2011-03-29 23:03:02.920225449 -0700
@@ -277,25 +277,6 @@
load_cr3(swapper_pg_dir);
#endif

-#ifdef CONFIG_X86_64
- if (!after_bootmem && !start) {
- pud_t *pud;
- pmd_t *pmd;
-
- mmu_cr4_features = read_cr4();
-
- /*
- * _brk_end cannot change anymore, but it and _end may be
- * located on different 2M pages. cleanup_highmap(), however,
- * can only consider _end when it runs, so destroy any
- * mappings beyond _brk_end here.
- */
- pud = pud_offset(pgd_offset_k(_brk_end), _brk_end);
- pmd = pmd_offset(pud, _brk_end - 1);
- while (++pmd <= pmd_offset(pud, (unsigned long)_end - 1))
- pmd_clear(pmd);
- }
-#endif
__flush_tlb_all();

if (!after_bootmem && e820_table_end > e820_table_start)
Index: linux-2.6.35.y/arch/x86/mm/init_64.c
===================================================================
--- linux-2.6.35.y.orig/arch/x86/mm/init_64.c 2011-03-29 22:50:26.228587294 -0700
+++ linux-2.6.35.y/arch/x86/mm/init_64.c 2011-03-29 23:03:02.921225423 -0700
@@ -50,6 +50,7 @@
#include <asm/numa.h>
#include <asm/cacheflush.h>
#include <asm/init.h>
+#include <asm/setup.h>
#include <linux/bootmem.h>

static unsigned long dma_reserve __initdata;
@@ -258,18 +259,18 @@
* to the compile time generated pmds. This results in invalid pmds up
* to the point where we hit the physaddr 0 mapping.
*
- * We limit the mappings to the region from _text to _end. _end is
- * rounded up to the 2MB boundary. This catches the invalid pmds as
+ * We limit the mappings to the region from _text to _brk_end. _brk_end
+ * is rounded up to the 2MB boundary. This catches the invalid pmds as
* well, as they are located before _text:
*/
void __init cleanup_highmap(void)
{
unsigned long vaddr = __START_KERNEL_map;
- unsigned long end = roundup((unsigned long)_end, PMD_SIZE) - 1;
+ unsigned long vaddr_end = __START_KERNEL_map + (max_pfn_mapped << PAGE_SHIFT);
+ unsigned long end = roundup((unsigned long)_brk_end, PMD_SIZE) - 1;
pmd_t *pmd = level2_kernel_pgt;
- pmd_t *last_pmd = pmd + PTRS_PER_PMD;

- for (; pmd < last_pmd; pmd++, vaddr += PMD_SIZE) {
+ for (; vaddr + PMD_SIZE - 1 < vaddr_end; pmd++, vaddr += PMD_SIZE) {
if (pmd_none(*pmd))
continue;
if (vaddr < (unsigned long) _text || vaddr > end)

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