x86, mm: Add alloc_low_pages(num)

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.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Link: http://lkml.kernel.org/r/1353123563-3103-28-git-send-email-yinghai@kernel.org
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
index 21173fc..02cea14 100644 (file)
--- 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 (file)
--- 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 */