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Subject[PATCH 27/46] x86, mm: Add alloc_low_pages(num)
Date
32bit kmap mapping needs pages to be used for low to high.
At this point those pages are still from pgt_buf_* from BRK, so it is
ok now.
But we want to move early_ioremap_page_table_range_init() out of
init_memory_mapping() and only call it one time later, that will
make page_table_range_init/page_table_kmap_check/alloc_low_page to
use memblock to get page.

memblock allocation for pages are from high to low.
So will get panic from page_table_kmap_check() that has BUG_ON to do
ordering checking.

This patch add alloc_low_pages to make it possible to allocate serveral
pages at first, and hand out pages one by one from low to high.

-v2: add one line comment about xen requirements.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
---
arch/x86/mm/init.c | 33 +++++++++++++++++++++------------
arch/x86/mm/mm_internal.h | 6 +++++-
2 files changed, 26 insertions(+), 13 deletions(-)

diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
index 9d51af72..f5e0120 100644
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -25,36 +25,45 @@ unsigned long __meminitdata pgt_buf_top;

static unsigned long min_pfn_mapped;

-__ref void *alloc_low_page(void)
+__ref void *alloc_low_pages(unsigned int num)
{
unsigned long pfn;
- void *adr;
+ int i;

#ifdef CONFIG_X86_64
if (after_bootmem) {
- adr = (void *)get_zeroed_page(GFP_ATOMIC | __GFP_NOTRACK);
+ unsigned int order;

- return adr;
+ order = get_order((unsigned long)num << PAGE_SHIFT);
+ return (void *)__get_free_pages(GFP_ATOMIC | __GFP_NOTRACK |
+ __GFP_ZERO, order);
}
#endif

- if ((pgt_buf_end + 1) >= pgt_buf_top) {
+ if ((pgt_buf_end + num) >= pgt_buf_top) {
unsigned long ret;
if (min_pfn_mapped >= max_pfn_mapped)
panic("alloc_low_page: ran out of memory");
ret = memblock_find_in_range(min_pfn_mapped << PAGE_SHIFT,
max_pfn_mapped << PAGE_SHIFT,
- PAGE_SIZE, PAGE_SIZE);
+ PAGE_SIZE * num , PAGE_SIZE);
if (!ret)
panic("alloc_low_page: can not alloc memory");
- memblock_reserve(ret, PAGE_SIZE);
+ memblock_reserve(ret, PAGE_SIZE * num);
pfn = ret >> PAGE_SHIFT;
- } else
- pfn = pgt_buf_end++;
+ } else {
+ pfn = pgt_buf_end;
+ pgt_buf_end += num;
+ }
+
+ for (i = 0; i < num; i++) {
+ void *adr;
+
+ adr = __va((pfn + i) << PAGE_SHIFT);
+ clear_page(adr);
+ }

- adr = __va(pfn * PAGE_SIZE);
- clear_page(adr);
- return adr;
+ return __va(pfn << PAGE_SHIFT);
}

/* need 4 4k for initial PMD_SIZE, 4k for 0-ISA_END_ADDRESS */
diff --git a/arch/x86/mm/mm_internal.h b/arch/x86/mm/mm_internal.h
index b3f993a..7e3b88e 100644
--- a/arch/x86/mm/mm_internal.h
+++ b/arch/x86/mm/mm_internal.h
@@ -1,6 +1,10 @@
#ifndef __X86_MM_INTERNAL_H
#define __X86_MM_INTERNAL_H

-void *alloc_low_page(void);
+void *alloc_low_pages(unsigned int num);
+static inline void *alloc_low_page(void)
+{
+ return alloc_low_pages(1);
+}

#endif /* __X86_MM_INTERNAL_H */
--
1.7.7


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