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Date: Wed, 16 May 2012 14:06:26 +0100
From: "Jan Beulich" <JBeulich@...e.com>
To: <mingo@...e.hu>, <tglx@...utronix.de>, <hpa@...or.com>
Cc: <linux-kernel@...r.kernel.org>
Subject: [PATCH] x86-64: fix accounting in
kernel_physical_mapping_init()
When finding a present and acceptable 2M/1G mapping, the number of
pages mapped this way shouldn't be incremented (as it was already
incremented when the earlier part of the mapping was established).
Instead, last_map_addr needs to be updated in this case.
Further, address increments were wrong in one place each in both
phys_pmd_init() and phys_pud_init() (lacking the aligning down to the
respective page boundary).
As we're now doing the same calculation several times, fold it into
a single instance using a local variable (matching how
kernel_physical_mapping_init() itself does it at the PGD level).
Observed during code inspection, not because of an actual problem.
Signed-off-by: Jan Beulich <jbeulich@...e.com>
---
arch/x86/mm/init_64.c | 23 +++++++++++++----------
1 file changed, 13 insertions(+), 10 deletions(-)
--- 3.4-rc7/arch/x86/mm/init_64.c
+++ 3.4-rc7-x86_64-mm-init-accounting/arch/x86/mm/init_64.c
@@ -407,12 +407,12 @@ static unsigned long __meminit
phys_pmd_init(pmd_t *pmd_page, unsigned long address, unsigned long end,
unsigned long page_size_mask, pgprot_t prot)
{
- unsigned long pages = 0;
+ unsigned long pages = 0, next;
unsigned long last_map_addr = end;
int i = pmd_index(address);
- for (; i < PTRS_PER_PMD; i++, address += PMD_SIZE) {
+ for (; i < PTRS_PER_PMD; i++, address = next) {
unsigned long pte_phys;
pmd_t *pmd = pmd_page + pmd_index(address);
pte_t *pte;
@@ -426,6 +426,8 @@ phys_pmd_init(pmd_t *pmd_page, unsigned
break;
}
+ next = (address & PMD_MASK) + PMD_SIZE;
+
if (pmd_val(*pmd)) {
if (!pmd_large(*pmd)) {
spin_lock(&init_mm.page_table_lock);
@@ -449,7 +451,7 @@ phys_pmd_init(pmd_t *pmd_page, unsigned
* attributes.
*/
if (page_size_mask & (1 << PG_LEVEL_2M)) {
- pages++;
+ last_map_addr = next;
continue;
}
new_prot = pte_pgprot(pte_clrhuge(*(pte_t *)pmd));
@@ -462,7 +464,7 @@ phys_pmd_init(pmd_t *pmd_page, unsigned
pfn_pte(address >> PAGE_SHIFT,
__pgprot(pgprot_val(prot) | _PAGE_PSE)));
spin_unlock(&init_mm.page_table_lock);
- last_map_addr = (address & PMD_MASK) + PMD_SIZE;
+ last_map_addr = next;
continue;
}
@@ -482,11 +484,11 @@ static unsigned long __meminit
phys_pud_init(pud_t *pud_page, unsigned long addr, unsigned long end,
unsigned long page_size_mask)
{
- unsigned long pages = 0;
+ unsigned long pages = 0, next;
unsigned long last_map_addr = end;
int i = pud_index(addr);
- for (; i < PTRS_PER_PUD; i++, addr = (addr & PUD_MASK) + PUD_SIZE) {
+ for (; i < PTRS_PER_PUD; i++, addr = next) {
unsigned long pmd_phys;
pud_t *pud = pud_page + pud_index(addr);
pmd_t *pmd;
@@ -495,8 +497,9 @@ phys_pud_init(pud_t *pud_page, unsigned
if (addr >= end)
break;
- if (!after_bootmem &&
- !e820_any_mapped(addr, addr+PUD_SIZE, 0)) {
+ next = (addr & PUD_MASK) + PUD_SIZE;
+
+ if (!after_bootmem && !e820_any_mapped(addr, next, 0)) {
set_pud(pud, __pud(0));
continue;
}
@@ -523,7 +526,7 @@ phys_pud_init(pud_t *pud_page, unsigned
* attributes.
*/
if (page_size_mask & (1 << PG_LEVEL_1G)) {
- pages++;
+ last_map_addr = next;
continue;
}
prot = pte_pgprot(pte_clrhuge(*(pte_t *)pud));
@@ -535,7 +538,7 @@ phys_pud_init(pud_t *pud_page, unsigned
set_pte((pte_t *)pud,
pfn_pte(addr >> PAGE_SHIFT, PAGE_KERNEL_LARGE));
spin_unlock(&init_mm.page_table_lock);
- last_map_addr = (addr & PUD_MASK) + PUD_SIZE;
+ last_map_addr = next;
continue;
}
--
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