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authorKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>2007-10-16 01:26:11 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-10-16 09:43:02 -0700
commita5d76b54a3f3a40385d7f76069a2feac9f1bad63 (patch)
treef58c432a4224b3be032bd4a4afa79dfa55d198a6 /mm
parent75884fb1c6388f3713ddcca662f3647b3129aaeb (diff)
downloadop-kernel-dev-a5d76b54a3f3a40385d7f76069a2feac9f1bad63.zip
op-kernel-dev-a5d76b54a3f3a40385d7f76069a2feac9f1bad63.tar.gz
memory unplug: page isolation
Implement generic chunk-of-pages isolation method by using page grouping ops. This patch add MIGRATE_ISOLATE to MIGRATE_TYPES. By this - MIGRATE_TYPES increases. - bitmap for migratetype is enlarged. pages of MIGRATE_ISOLATE migratetype will not be allocated even if it is free. By this, you can isolated *freed* pages from users. How-to-free pages is not a purpose of this patch. You may use reclaim and migrate codes to free pages. If start_isolate_page_range(start,end) is called, - migratetype of the range turns to be MIGRATE_ISOLATE if its type is MIGRATE_MOVABLE. (*) this check can be updated if other memory reclaiming works make progress. - MIGRATE_ISOLATE is not on migratetype fallback list. - All free pages and will-be-freed pages are isolated. To check all pages in the range are isolated or not, use test_pages_isolated(), To cancel isolation, use undo_isolate_page_range(). Changes V6 -> V7 - removed unnecessary #ifdef There are HOLES_IN_ZONE handling codes...I'm glad if we can remove them.. Signed-off-by: Yasunori Goto <y-goto@jp.fujitsu.com> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/Makefile2
-rw-r--r--mm/page_alloc.c44
-rw-r--r--mm/page_isolation.c138
3 files changed, 183 insertions, 1 deletions
diff --git a/mm/Makefile b/mm/Makefile
index d28f63e..5c0b0ea 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -11,7 +11,7 @@ obj-y := bootmem.o filemap.o mempool.o oom_kill.o fadvise.o \
page_alloc.o page-writeback.o pdflush.o \
readahead.o swap.o truncate.o vmscan.o \
prio_tree.o util.o mmzone.o vmstat.o backing-dev.o \
- $(mmu-y)
+ page_isolation.o $(mmu-y)
obj-$(CONFIG_BOUNCE) += bounce.o
obj-$(CONFIG_SWAP) += page_io.o swap_state.o swapfile.o thrash.o
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 71ced51..a44715e 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -41,6 +41,7 @@
#include <linux/pfn.h>
#include <linux/backing-dev.h>
#include <linux/fault-inject.h>
+#include <linux/page-isolation.h>
#include <asm/tlbflush.h>
#include <asm/div64.h>
@@ -4433,3 +4434,46 @@ void set_pageblock_flags_group(struct page *page, unsigned long flags,
else
__clear_bit(bitidx + start_bitidx, bitmap);
}
+
+/*
+ * This is designed as sub function...plz see page_isolation.c also.
+ * set/clear page block's type to be ISOLATE.
+ * page allocater never alloc memory from ISOLATE block.
+ */
+
+int set_migratetype_isolate(struct page *page)
+{
+ struct zone *zone;
+ unsigned long flags;
+ int ret = -EBUSY;
+
+ zone = page_zone(page);
+ spin_lock_irqsave(&zone->lock, flags);
+ /*
+ * In future, more migrate types will be able to be isolation target.
+ */
+ if (get_pageblock_migratetype(page) != MIGRATE_MOVABLE)
+ goto out;
+ set_pageblock_migratetype(page, MIGRATE_ISOLATE);
+ move_freepages_block(zone, page, MIGRATE_ISOLATE);
+ ret = 0;
+out:
+ spin_unlock_irqrestore(&zone->lock, flags);
+ if (!ret)
+ drain_all_local_pages();
+ return ret;
+}
+
+void unset_migratetype_isolate(struct page *page)
+{
+ struct zone *zone;
+ unsigned long flags;
+ zone = page_zone(page);
+ spin_lock_irqsave(&zone->lock, flags);
+ if (get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
+ goto out;
+ set_pageblock_migratetype(page, MIGRATE_MOVABLE);
+ move_freepages_block(zone, page, MIGRATE_MOVABLE);
+out:
+ spin_unlock_irqrestore(&zone->lock, flags);
+}
diff --git a/mm/page_isolation.c b/mm/page_isolation.c
new file mode 100644
index 0000000..8f92a29
--- /dev/null
+++ b/mm/page_isolation.c
@@ -0,0 +1,138 @@
+/*
+ * linux/mm/page_isolation.c
+ */
+
+#include <stddef.h>
+#include <linux/mm.h>
+#include <linux/page-isolation.h>
+#include <linux/pageblock-flags.h>
+#include "internal.h"
+
+static inline struct page *
+__first_valid_page(unsigned long pfn, unsigned long nr_pages)
+{
+ int i;
+ for (i = 0; i < nr_pages; i++)
+ if (pfn_valid_within(pfn + i))
+ break;
+ if (unlikely(i == nr_pages))
+ return NULL;
+ return pfn_to_page(pfn + i);
+}
+
+/*
+ * start_isolate_page_range() -- make page-allocation-type of range of pages
+ * to be MIGRATE_ISOLATE.
+ * @start_pfn: The lower PFN of the range to be isolated.
+ * @end_pfn: The upper PFN of the range to be isolated.
+ *
+ * Making page-allocation-type to be MIGRATE_ISOLATE means free pages in
+ * the range will never be allocated. Any free pages and pages freed in the
+ * future will not be allocated again.
+ *
+ * start_pfn/end_pfn must be aligned to pageblock_order.
+ * Returns 0 on success and -EBUSY if any part of range cannot be isolated.
+ */
+int
+start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn)
+{
+ unsigned long pfn;
+ unsigned long undo_pfn;
+ struct page *page;
+
+ BUG_ON((start_pfn) & (pageblock_nr_pages - 1));
+ BUG_ON((end_pfn) & (pageblock_nr_pages - 1));
+
+ for (pfn = start_pfn;
+ pfn < end_pfn;
+ pfn += pageblock_nr_pages) {
+ page = __first_valid_page(pfn, pageblock_nr_pages);
+ if (page && set_migratetype_isolate(page)) {
+ undo_pfn = pfn;
+ goto undo;
+ }
+ }
+ return 0;
+undo:
+ for (pfn = start_pfn;
+ pfn <= undo_pfn;
+ pfn += pageblock_nr_pages)
+ unset_migratetype_isolate(pfn_to_page(pfn));
+
+ return -EBUSY;
+}
+
+/*
+ * Make isolated pages available again.
+ */
+int
+undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn)
+{
+ unsigned long pfn;
+ struct page *page;
+ BUG_ON((start_pfn) & (pageblock_nr_pages - 1));
+ BUG_ON((end_pfn) & (pageblock_nr_pages - 1));
+ for (pfn = start_pfn;
+ pfn < end_pfn;
+ pfn += pageblock_nr_pages) {
+ page = __first_valid_page(pfn, pageblock_nr_pages);
+ if (!page || get_pageblock_flags(page) != MIGRATE_ISOLATE)
+ continue;
+ unset_migratetype_isolate(page);
+ }
+ return 0;
+}
+/*
+ * Test all pages in the range is free(means isolated) or not.
+ * all pages in [start_pfn...end_pfn) must be in the same zone.
+ * zone->lock must be held before call this.
+ *
+ * Returns 0 if all pages in the range is isolated.
+ */
+static int
+__test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn)
+{
+ struct page *page;
+
+ while (pfn < end_pfn) {
+ if (!pfn_valid_within(pfn)) {
+ pfn++;
+ continue;
+ }
+ page = pfn_to_page(pfn);
+ if (PageBuddy(page))
+ pfn += 1 << page_order(page);
+ else if (page_count(page) == 0 &&
+ page_private(page) == MIGRATE_ISOLATE)
+ pfn += 1;
+ else
+ break;
+ }
+ if (pfn < end_pfn)
+ return 0;
+ return 1;
+}
+
+int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn)
+{
+ unsigned long pfn;
+ struct page *page;
+
+ pfn = start_pfn;
+ /*
+ * Note: pageblock_nr_page != MAX_ORDER. Then, chunks of free page
+ * is not aligned to pageblock_nr_pages.
+ * Then we just check pagetype fist.
+ */
+ for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
+ page = __first_valid_page(pfn, pageblock_nr_pages);
+ if (page && get_pageblock_flags(page) != MIGRATE_ISOLATE)
+ break;
+ }
+ if (pfn < end_pfn)
+ return -EBUSY;
+ /* Check all pages are free or Marked as ISOLATED */
+ if (__test_page_isolated_in_pageblock(start_pfn, end_pfn))
+ return 0;
+ return -EBUSY;
+}
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