Hi Tang,
On Tue, Aug 27, 2013 at 05:37:47PM +0800, Tang Chen wrote:
>init_mem_mapping() is called before SRAT is parsed. And memblock will allocate
>memory for page tables. To prevent page tables being allocated within hotpluggable
>memory, we will allocate page tables from the end of kernel image to the higher
>memory.
>
>The order of page tables allocation is controled by movablenode boot option.
>Since the default behavior of page tables initialization procedure is allocate
>page tables from top of the memory downwards, if users don't specify movablenode
>boot option, the kernel will behave as before.
>
>Signed-off-by: Tang Chen <tangchen@xxxxxxxxxxxxxx>
>Reviewed-by: Zhang Yanfei <zhangyanfei@xxxxxxxxxxxxxx>
>---
> arch/x86/mm/init.c | 119 +++++++++++++++++++++++++++++++++++++++------------
> 1 files changed, 91 insertions(+), 28 deletions(-)
>
>diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
>index 793204b..f004d8e 100644
>--- a/arch/x86/mm/init.c
>+++ b/arch/x86/mm/init.c
>@@ -407,13 +407,77 @@ static unsigned long __init init_range_memory_mapping(
>
> /* (PUD_SHIFT-PMD_SHIFT)/2 */
> #define STEP_SIZE_SHIFT 5
>-void __init init_mem_mapping(void)
>+
>+#ifdef CONFIG_MOVABLE_NODE
>+/**
>+ * memory_map_from_low - Map [start, end) from low to high
>+ * @start: start address of the target memory range
>+ * @end: end address of the target memory range
>+ *
>+ * This function will setup direct mapping for memory range [start, end) in a
>+ * heuristic way. In the beginning, step_size is small. The more memory we map
>+ * memory in the next loop.
>+ */
>+static void __init memory_map_from_low(unsigned long start, unsigned long end)
>+{
>+ unsigned long next, new_mapped_ram_size;
>+ unsigned long mapped_ram_size = 0;
>+ /* step_size need to be small so pgt_buf from BRK could cover it */
>+ unsigned long step_size = PMD_SIZE;
>+
>+ while (start < end) {
>+ if (end - start > step_size) {
>+ next = round_up(start + 1, step_size);
>+ if (next > end)
>+ next = end;
>+ } else
>+ next = end;
>+
>+ new_mapped_ram_size = init_range_memory_mapping(start, next);
>+ start = next;
>+
>+ if (new_mapped_ram_size > mapped_ram_size)
>+ step_size <<= STEP_SIZE_SHIFT;
>+ mapped_ram_size += new_mapped_ram_size;
>+ }
>+}
>+#endif /* CONFIG_MOVABLE_NODE */
>+
>+/**
>+ * memory_map_from_high - Map [start, end) from high to low
>+ * @start: start address of the target memory range
>+ * @end: end address of the target memory range
>+ *
>+ * This function is similar to memory_map_from_low() except it maps memory
>+ * from high to low.
>+ */
>+static void __init memory_map_from_high(unsigned long start, unsigned long end)
> {
>- unsigned long end, real_end, start, last_start;
>- unsigned long step_size;
>- unsigned long addr;
>+ unsigned long prev, new_mapped_ram_size;
> unsigned long mapped_ram_size = 0;
>- unsigned long new_mapped_ram_size;
>+ /* step_size need to be small so pgt_buf from BRK could cover it */
>+ unsigned long step_size = PMD_SIZE;
>+
>+ while (start < end) {
>+ if (end > step_size) {
>+ prev = round_down(end - 1, step_size);
>+ if (prev < start)
>+ prev = start;
>+ } else
>+ prev = start;
>+
>+ new_mapped_ram_size = init_range_memory_mapping(prev, end);
>+ end = prev;
>+
>+ if (new_mapped_ram_size > mapped_ram_size)
>+ step_size <<= STEP_SIZE_SHIFT;
>+ mapped_ram_size += new_mapped_ram_size;
>+ }
>+}
>+
>+void __init init_mem_mapping(void)
>+{
>+ unsigned long end;
>
> probe_page_size_mask();
>
>@@ -423,44 +487,43 @@ void __init init_mem_mapping(void)
> end = max_low_pfn << PAGE_SHIFT;
> #endif
>
>- /* the ISA range is always mapped regardless of memory holes */
>- init_memory_mapping(0, ISA_END_ADDRESS);
>+ max_pfn_mapped = 0; /* will get exact value next */
>+ min_pfn_mapped = end >> PAGE_SHIFT;
>+
>+#ifdef CONFIG_MOVABLE_NODE
>+ unsigned long kernel_end;
>+
>+ if (movablenode_enable_srat &&
>+ memblock.current_order == MEMBLOCK_ORDER_LOW_TO_HIGH) {
I think memblock.current_order == MEMBLOCK_ORDER_LOW_TO_HIGH is always
true if config MOVABLE_NODE and movablenode_enable_srat == true if PATCH
11/11 is applied.
>+ kernel_end = round_up(__pa_symbol(_end), PMD_SIZE);
>+
>+ memory_map_from_low(kernel_end, end);
>+ memory_map_from_low(ISA_END_ADDRESS, kernel_end);
Why split ISA_END_ADDRESS ~ end?
>+ goto out;
>+ }
>+#endif /* CONFIG_MOVABLE_NODE */
>+
>+ unsigned long addr, real_end;
>
> /* xen has big range in reserved near end of ram, skip it at first.*/
> addr = memblock_find_in_range(ISA_END_ADDRESS, end, PMD_SIZE, PMD_SIZE);
> real_end = addr + PMD_SIZE;
>
>- /* step_size need to be small so pgt_buf from BRK could cover it */
>- step_size = PMD_SIZE;
>- max_pfn_mapped = 0; /* will get exact value next */
>- min_pfn_mapped = real_end >> PAGE_SHIFT;
>- last_start = start = real_end;
>-
> /*
> * We start from the top (end of memory) and go to the bottom.
> * The memblock_find_in_range() gets us a block of RAM from the
> * end of RAM in [min_pfn_mapped, max_pfn_mapped) used as new pages
> * for page table.
> */
>- while (last_start > ISA_END_ADDRESS) {
>- if (last_start > step_size) {
>- start = round_down(last_start - 1, step_size);
>- if (start < ISA_END_ADDRESS)
>- start = ISA_END_ADDRESS;
>- } else
>- start = ISA_END_ADDRESS;
>- new_mapped_ram_size = init_range_memory_mapping(start,
>- last_start);
>- last_start = start;
>- /* only increase step_size after big range get mapped */
>- if (new_mapped_ram_size > mapped_ram_size)
>- step_size <<= STEP_SIZE_SHIFT;
>- mapped_ram_size += new_mapped_ram_size;
>- }
I think the variables sorted by address is:
ISA_END_ADDRESS -> _end -> real_end -> end
>+ memory_map_from_high(ISA_END_ADDRESS, real_end);
If this is overlap with work done between #ifdef CONFIG_MOVABLE_NODE and
#endif?
Regards,
Wanpeng LI
>
> if (real_end < end)
> init_range_memory_mapping(real_end, end);
>
>+out:
>+ /* the ISA range is always mapped regardless of memory holes */
>+ init_memory_mapping(0, ISA_END_ADDRESS);
>+
> #ifdef CONFIG_X86_64
> if (max_pfn > max_low_pfn) {
> /* can we preseve max_low_pfn ?*/
>--
>1.7.1
>
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