Hi Wu,
I met some problems when I was digging into the code. It's very
kind of you if you could help me with that. :)
If I misunderstood your code, please tell me.
Please see below. :)
On 12/03/2012 10:23 AM, Jianguo Wu wrote:
Signed-off-by: Jianguo Wu<wujianguo@xxxxxxxxxx>
Signed-off-by: Jiang Liu<jiang.liu@xxxxxxxxxx>
---
include/linux/mm.h | 1 +
mm/sparse-vmemmap.c | 231 +++++++++++++++++++++++++++++++++++++++++++++++++++
mm/sparse.c | 3 +-
3 files changed, 234 insertions(+), 1 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 5657670..1f26af5 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1642,6 +1642,7 @@ int vmemmap_populate(struct page *start_page, unsigned long pages, int node);
void vmemmap_populate_print_last(void);
void register_page_bootmem_memmap(unsigned long section_nr, struct page *map,
unsigned long size);
+void vmemmap_free(struct page *memmap, unsigned long nr_pages);
enum mf_flags {
MF_COUNT_INCREASED = 1<< 0,
diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c
index 1b7e22a..748732d 100644
--- a/mm/sparse-vmemmap.c
+++ b/mm/sparse-vmemmap.c
@@ -29,6 +29,10 @@
#include<asm/pgalloc.h>
#include<asm/pgtable.h>
+#ifdef CONFIG_MEMORY_HOTREMOVE
+#include<asm/tlbflush.h>
+#endif
+
/*
* Allocate a block of memory to be used to back the virtual memory map
* or to back the page tables that are used to create the mapping.
@@ -224,3 +228,230 @@ void __init sparse_mem_maps_populate_node(struct page **map_map,
vmemmap_buf_end = NULL;
}
}
+
+#ifdef CONFIG_MEMORY_HOTREMOVE
+
+#define PAGE_INUSE 0xFD
+
+static void vmemmap_free_pages(struct page *page, int order)
+{
+ struct zone *zone;
+ unsigned long magic;
+
+ magic = (unsigned long) page->lru.next;
+ if (magic == SECTION_INFO || magic == MIX_SECTION_INFO) {
+ put_page_bootmem(page);
+
+ zone = page_zone(page);
+ zone_span_writelock(zone);
+ zone->present_pages++;
+ zone_span_writeunlock(zone);
+ totalram_pages++;
+ } else
+ free_pages((unsigned long)page_address(page), order);
Here, I think SECTION_INFO and MIX_SECTION_INFO pages are all allocated
by bootmem, so I put this function this way.
I'm not sure if parameter order is necessary here. It will always be 0
in your code. Is this OK to you ?
static void free_pagetable(struct page *page)
{
struct zone *zone;
bool bootmem = false;
unsigned long magic;
/* bootmem page has reserved flag */
if (PageReserved(page)) {
__ClearPageReserved(page);
bootmem = true;
}
magic = (unsigned long) page->lru.next;
if (magic == SECTION_INFO || magic == MIX_SECTION_INFO)
put_page_bootmem(page);
else
__free_page(page);
/*
* SECTION_INFO pages and MIX_SECTION_INFO pages
* are all allocated by bootmem.
*/
if (bootmem) {
zone = page_zone(page);
zone_span_writelock(zone);
zone->present_pages++;
zone_span_writeunlock(zone);
totalram_pages++;
}
}
(snip)
+
+static void vmemmap_pte_remove(pmd_t *pmd, unsigned long addr, unsigned long end)
+{
+ pte_t *pte;
+ unsigned long next;
+ void *page_addr;
+
+ pte = pte_offset_kernel(pmd, addr);
+ for (; addr< end; pte++, addr += PAGE_SIZE) {
+ next = (addr + PAGE_SIZE)& PAGE_MASK;
+ if (next> end)
+ next = end;
+
+ if (pte_none(*pte))
Here, you checked xxx_none() in your vmemmap_xxx_remove(), but you used
!xxx_present() in your x86_64 patches. Is it OK if I only check
!xxx_present() ?
+ continue;
+ if (IS_ALIGNED(addr, PAGE_SIZE)&&
+ IS_ALIGNED(next, PAGE_SIZE)) {
+ vmemmap_free_pages(pte_page(*pte), 0);
+ spin_lock(&init_mm.page_table_lock);
+ pte_clear(&init_mm, addr, pte);
+ spin_unlock(&init_mm.page_table_lock);
+ } else {
+ /*
+ * Removed page structs are filled with 0xFD.
+ */
+ memset((void *)addr, PAGE_INUSE, next - addr);
+ page_addr = page_address(pte_page(*pte));
+
+ if (!memchr_inv(page_addr, PAGE_INUSE, PAGE_SIZE)) {
+ spin_lock(&init_mm.page_table_lock);
+ pte_clear(&init_mm, addr, pte);
+ spin_unlock(&init_mm.page_table_lock);
Here, since we clear pte, we should also free the page, right ?
+ }
+ }
+ }
+
+ free_pte_table(pmd);
+ __flush_tlb_all();
+}
+
+static void vmemmap_pmd_remove(pud_t *pud, unsigned long addr, unsigned long end)
+{
+ unsigned long next;
+ pmd_t *pmd;
+
+ pmd = pmd_offset(pud, addr);
+ for (; addr< end; addr = next, pmd++) {
+ next = (addr, end);
And by the way, there isn't pte_addr_end() in kernel, why ?
I saw you calculated it like this:
next = (addr + PAGE_SIZE) & PAGE_MASK;
if (next > end)
next = end;
This logic is very similar to {pmd|pud|pgd}_addr_end(). Shall we add a
pte_addr_end() or something ? :)
Since there is no such code in kernel for a long time, I think there
must be some reasons.
I merged free_xxx_table() and remove_xxx_table() as common interfaces.
And again, thanks for your patient and nice explanation. :)
(snip)
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