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| author | KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> | 2007-08-30 23:56:21 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-08-31 01:42:22 -0700 |
| commit | 989f89c57e6361e7d16fbd9572b5da7d313b073d (patch) | |
| tree | cd5f655709e1515568c1e1f309f169723ce3b084 | |
| parent | d1254b12c93e1e586137a2ffef71fd33cf273f35 (diff) | |
| download | lwn-989f89c57e6361e7d16fbd9572b5da7d313b073d.tar.gz lwn-989f89c57e6361e7d16fbd9572b5da7d313b073d.zip | |
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>
| -rw-r--r-- | mm/migrate.c | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/mm/migrate.c b/mm/migrate.c index 37c73b902008..e2fdbce1874b 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: |