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authorKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>2007-08-30 23:56:21 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-08-31 01:42:22 -0700
commit989f89c57e6361e7d16fbd9572b5da7d313b073d (patch)
treecd5f655709e1515568c1e1f309f169723ce3b084 /mm
parentd1254b12c93e1e586137a2ffef71fd33cf273f35 (diff)
downloadlinux-linaro-989f89c57e6361e7d16fbd9572b5da7d313b073d.tar.gz
fix rcu_read_lock() in page migraton
In migration fallback path, write_page() or lock_page() will be called. This causes sleep with holding rcu_read_lock(). For avoding that, just do rcu_lock if the page is Anon.(this is enough.) Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Christoph Lameter <clameter@sgi.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/migrate.c11
1 files changed, 9 insertions, 2 deletions
diff --git a/mm/migrate.c b/mm/migrate.c
index 37c73b90200..e2fdbce1874 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -611,6 +611,7 @@ static int unmap_and_move(new_page_t get_new_page, unsigned long private,
int rc = 0;
int *result = NULL;
struct page *newpage = get_new_page(page, private, &result);
+ int rcu_locked = 0;
if (!newpage)
return -ENOMEM;
@@ -636,8 +637,13 @@ static int unmap_and_move(new_page_t get_new_page, unsigned long private,
* we cannot notice that anon_vma is freed while we migrates a page.
* This rcu_read_lock() delays freeing anon_vma pointer until the end
* of migration. File cache pages are no problem because of page_lock()
+ * File Caches may use write_page() or lock_page() in migration, then,
+ * just care Anon page here.
*/
- rcu_read_lock();
+ if (PageAnon(page)) {
+ rcu_read_lock();
+ rcu_locked = 1;
+ }
/*
* This is a corner case handling.
* When a new swap-cache is read into, it is linked to LRU
@@ -656,7 +662,8 @@ static int unmap_and_move(new_page_t get_new_page, unsigned long private,
if (rc)
remove_migration_ptes(page, page);
rcu_unlock:
- rcu_read_unlock();
+ if (rcu_locked)
+ rcu_read_unlock();
unlock: