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Subject[PATCH 1/3] x86: calculate precisely the memory needed by init_memory_mapping
Date
From: Stefano Stabellini <stefano.stabellini@eu.citrix.com>

- take into account the size of the initial pagetable;

- remove the extra PMD_SIZE added when use_pse, because the previously
allocated PMDs are always 2M aligned;

- remove the extra page added on x86_32 for the fixmap because is not
needed: the PMD entry is already allocated and contiguous for the whole
range (a PMD page covers 4G of virtual addresses) and the pte entry is
already allocated by early_ioremap_init.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
arch/x86/mm/init.c | 62 ++++++++++++++++++++++++++++++++++++++-------------
1 files changed, 46 insertions(+), 16 deletions(-)
diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
index 3032644..0cfe8d4 100644
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -28,22 +28,52 @@ int direct_gbpages
#endif
;

-static void __init find_early_table_space(unsigned long end, int use_pse,
- int use_gbpages)
+static void __init find_early_table_space(unsigned long start,
+ unsigned long end, int use_pse, int use_gbpages)
{
- unsigned long puds, pmds, ptes, tables, start = 0, good_end = end;
+ unsigned long pmds = 0, ptes = 0, tables = 0, good_end = end,
+ pud_mapped = 0, pmd_mapped = 0, size = end - start;
phys_addr_t base;

- puds = (end + PUD_SIZE - 1) >> PUD_SHIFT;
- tables = roundup(puds * sizeof(pud_t), PAGE_SIZE);
+ pud_mapped = DIV_ROUND_UP(PFN_PHYS(max_pfn_mapped),
+ (PUD_SIZE * PTRS_PER_PUD));
+ pud_mapped *= (PUD_SIZE * PTRS_PER_PUD);
+ pmd_mapped = DIV_ROUND_UP(PFN_PHYS(max_pfn_mapped),
+ (PMD_SIZE * PTRS_PER_PMD));
+ pmd_mapped *= (PMD_SIZE * PTRS_PER_PMD);
+
+ if (start < PFN_PHYS(max_pfn_mapped)) {
+ if (PFN_PHYS(max_pfn_mapped) < end)
+ size -= PFN_PHYS(max_pfn_mapped) - start;
+ else
+ size = 0;
+ }
+
+#ifndef __PAGETABLE_PUD_FOLDED
+ if (end > pud_mapped) {
+ unsigned long puds;
+ if (start < pud_mapped)
+ puds = (end - pud_mapped + PUD_SIZE - 1) >> PUD_SHIFT;
+ else
+ puds = (end - start + PUD_SIZE - 1) >> PUD_SHIFT;
+ tables += roundup(puds * sizeof(pud_t), PAGE_SIZE);
+ }
+#endif

if (use_gbpages) {
unsigned long extra;

extra = end - ((end>>PUD_SHIFT) << PUD_SHIFT);
pmds = (extra + PMD_SIZE - 1) >> PMD_SHIFT;
- } else
- pmds = (end + PMD_SIZE - 1) >> PMD_SHIFT;
+ }
+#ifndef __PAGETABLE_PMD_FOLDED
+ else if (end > pmd_mapped) {
+ if (start < pmd_mapped)
+ pmds = (end - pmd_mapped + PMD_SIZE - 1) >> PMD_SHIFT;
+ else
+ pmds = (end - start + PMD_SIZE - 1) >> PMD_SHIFT;
+ }
+#endif

tables += roundup(pmds * sizeof(pmd_t), PAGE_SIZE);

@@ -51,23 +81,20 @@ static void __init find_early_table_space(unsigned long end, int use_pse,
unsigned long extra;

extra = end - ((end>>PMD_SHIFT) << PMD_SHIFT);
-#ifdef CONFIG_X86_32
- extra += PMD_SIZE;
-#endif
ptes = (extra + PAGE_SIZE - 1) >> PAGE_SHIFT;
} else
- ptes = (end + PAGE_SIZE - 1) >> PAGE_SHIFT;
+ ptes = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;

tables += roundup(ptes * sizeof(pte_t), PAGE_SIZE);

-#ifdef CONFIG_X86_32
- /* for fixmap */
- tables += roundup(__end_of_fixed_addresses * sizeof(pte_t), PAGE_SIZE);
+ if (!tables)
+ return;

+#ifdef CONFIG_X86_32
good_end = max_pfn_mapped << PAGE_SHIFT;
#endif

- base = memblock_find_in_range(start, good_end, tables, PAGE_SIZE);
+ base = memblock_find_in_range(0x00, good_end, tables, PAGE_SIZE);
if (base == MEMBLOCK_ERROR)
panic("Cannot find space for the kernel page tables");

@@ -261,7 +288,7 @@ unsigned long __init_refok init_memory_mapping(unsigned long start,
* nodes are discovered.
*/
if (!after_bootmem)
- find_early_table_space(end, use_pse, use_gbpages);
+ find_early_table_space(start, end, use_pse, use_gbpages);

for (i = 0; i < nr_range; i++)
ret = kernel_physical_mapping_init(mr[i].start, mr[i].end,
@@ -275,6 +302,9 @@ unsigned long __init_refok init_memory_mapping(unsigned long start,

__flush_tlb_all();

+ if (pgt_buf_end != pgt_buf_top)
+ printk(KERN_DEBUG "initial kernel pagetable allocation wasted %lx"
+ " pages\n", pgt_buf_top - pgt_buf_end);
/*
* Reserve the kernel pagetable pages we used (pgt_buf_start -
* pgt_buf_end) and free the other ones (pgt_buf_end - pgt_buf_top)
--
1.7.2.3


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