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Message-Id: <20070509120913.B918.Y-GOTO@jp.fujitsu.com>
Date: Wed, 09 May 2007 12:12:17 +0900
From: Yasunori Goto <y-goto@...fujitsu.com>
To: Linux Kernel ML <linux-kernel@...r.kernel.org>,
linux-mm <linux-mm@...ck.org>
Cc: Andrew Morton <akpm@...l.org>,
Christoph Lameter <clameter@....com>,
Mel Gorman <mel@....ul.ie>
Subject: [RFC] memory hotremove patch take 2 [09/10] (direct isolation for remove)
This patch is to isolate source page of migration ASAP in unmap_and_move(),
when memory-hotremove.
In old code, it uses just put_page(),
and we expected that migrated source page is catched in __free_one_page()
as isolated page. But, it is spooled in per_cpu_page and used soon
for next destination page of migration. This was cause of eternal loop in
offline_pages().
Signed-off-by: Yasunori Goto <y-goto@...fujitsu.com>
include/linux/page_isolation.h | 14 ++++++++++++
mm/Kconfig | 1
mm/migrate.c | 46 +++++++++++++++++++++++++++++++++++++++--
3 files changed, 59 insertions(+), 2 deletions(-)
Index: current_test/mm/migrate.c
===================================================================
--- current_test.orig/mm/migrate.c 2007-05-08 15:08:07.000000000 +0900
+++ current_test/mm/migrate.c 2007-05-08 15:08:21.000000000 +0900
@@ -249,6 +249,32 @@ static void remove_migration_ptes(struct
remove_file_migration_ptes(old, new);
}
+
+static int
+is_page_isolated_noinfo(struct page *page)
+{
+ int ret = 0;
+ struct zone *zone;
+ unsigned long flags;
+ struct isolation_info *info;
+
+ if (unlikely(PageReserved(page) && PagePrivate(page) &&
+ page_count(page) == 1)){
+ zone = page_zone(page);
+ spin_lock_irqsave(&zone->isolation_lock, flags);
+ list_for_each_entry(info, &zone->isolation_list, list) {
+ if (PageReserved(page) && PagePrivate(page) &&
+ page_count(page) == 1 &&
+ page->private == (unsigned long)info){
+ ret = 1;
+ break;
+ }
+ }
+ spin_unlock_irqrestore(&zone->isolation_lock, flags);
+
+ }
+ return ret;
+}
/*
* Something used the pte of a page under migration. We need to
* get to the page and wait until migration is finished.
@@ -278,7 +304,14 @@ void migration_entry_wait(struct mm_stru
get_page(page);
pte_unmap_unlock(ptep, ptl);
wait_on_page_locked(page);
- put_page(page);
+
+ /*
+ * The page might be migrated and directly isolated.
+ * If not, then release page.
+ */
+ if (!is_page_isolated_noinfo(page))
+ put_page(page);
+
return;
out:
pte_unmap_unlock(ptep, ptl);
@@ -653,6 +686,15 @@ static int unmap_and_move(new_page_t get
anon_vma_release(page);
}
+ if (rc != -EAGAIN && is_migrate_isolation(flag)) {
+ /* page must be removed sooner. */
+ list_del(&page->lru);
+ page_under_isolation(page_zone(page), page, 0);
+ __put_page(page);
+ unlock_page(page);
+ goto move_newpage;
+ }
+
unlock:
unlock_page(page);
@@ -758,7 +800,7 @@ int migrate_pages_and_remove(struct list
new_page_t get_new_page, unsigned long private)
{
return __migrate_pages(from, get_new_page, private,
- MIGRATE_NOCONTEXT);
+ MIGRATE_NOCONTEXT | MIGRATE_ISOLATION);
}
#endif
Index: current_test/include/linux/page_isolation.h
===================================================================
--- current_test.orig/include/linux/page_isolation.h 2007-05-08 15:08:07.000000000 +0900
+++ current_test/include/linux/page_isolation.h 2007-05-08 15:08:09.000000000 +0900
@@ -33,12 +33,20 @@ is_page_isolated(struct isolation_info *
}
#define MIGRATE_NOCONTEXT 0x1
+#define MIGRATE_ISOLATION 0x2
+
static inline int
is_migrate_nocontext(int flag)
{
return (flag & MIGRATE_NOCONTEXT) == MIGRATE_NOCONTEXT;
}
+static inline int
+is_migrate_isolation(int flag)
+{
+ return (flag & MIGRATE_ISOLATION) == MIGRATE_ISOLATION;
+}
+
extern struct isolation_info *
register_isolation(unsigned long start, unsigned long end);
@@ -64,5 +72,11 @@ is_migrate_nocontext(int flag)
return 0;
}
+static inline int
+is_migrate_isolation(int flag)
+{
+ return 0;
+}
+
#endif
#endif
Index: current_test/mm/Kconfig
===================================================================
--- current_test.orig/mm/Kconfig 2007-05-08 15:08:07.000000000 +0900
+++ current_test/mm/Kconfig 2007-05-08 15:08:09.000000000 +0900
@@ -169,6 +169,7 @@ config MIGRATION_REMOVE
migration target pages. This has a small race condition.
If this config is selected, some workaround for fix them is enabled.
This may be add slight performance influence.
+ In addition, page must be isolated sooner for remove.
config RESOURCES_64BIT
bool "64 bit Memory and IO resources (EXPERIMENTAL)" if (!64BIT && EXPERIMENTAL)
--
Yasunori Goto
-
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