diff options
authorJan Kara <jack@suse.cz>2012-11-26 16:29:51 -0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2012-12-03 11:38:01 -0800
commit9c782bac5764db62c6e23f3d13faec003fc973f5 (patch)
parentdc541b2ba0e0aa83831ca99ba1e5a574e41d3c5b (diff)
writeback: put unused inodes to LRU after writeback completion
commit 4eff96dd5283a102e0c1cac95247090be74a38ed upstream. Commit 169ebd90131b ("writeback: Avoid iput() from flusher thread") removed iget-iput pair from inode writeback. As a side effect, inodes that are dirty during iput_final() call won't be ever added to inode LRU (iput_final() doesn't add dirty inodes to LRU and later when the inode is cleaned there's noone to add the inode there). Thus inodes are effectively unreclaimable until someone looks them up again. The practical effect of this bug is limited by the fact that inodes are pinned by a dentry for long enough that the inode gets cleaned. But still the bug can have nasty consequences leading up to OOM conditions under certain circumstances. Following can easily reproduce the problem: for (( i = 0; i < 1000; i++ )); do mkdir $i for (( j = 0; j < 1000; j++ )); do touch $i/$j echo 2 > /proc/sys/vm/drop_caches done done then one needs to run 'sync; ls -lR' to make inodes reclaimable again. We fix the issue by inserting unused clean inodes into the LRU after writeback finishes in inode_sync_complete(). Signed-off-by: Jan Kara <jack@suse.cz> Reported-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Dave Chinner <david@fromorbit.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
3 files changed, 17 insertions, 2 deletions
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 5602d73d4ec7..af321a6f71ff 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -228,6 +228,8 @@ static void requeue_io(struct inode *inode, struct bdi_writeback *wb)
static void inode_sync_complete(struct inode *inode)
inode->i_state &= ~I_SYNC;
+ /* If inode is clean an unused, put it into LRU now... */
+ inode_add_lru(inode);
/* Waiters must see I_SYNC cleared before being woken up */
wake_up_bit(&inode->i_state, __I_SYNC);
diff --git a/fs/inode.c b/fs/inode.c
index ac8d904b3f16..7c14897f9a9f 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -408,6 +408,19 @@ static void inode_lru_list_add(struct inode *inode)
+ * Add inode to LRU if needed (inode is unused and clean).
+ *
+ * Needs inode->i_lock held.
+ */
+void inode_add_lru(struct inode *inode)
+ if (!(inode->i_state & (I_DIRTY | I_SYNC | I_FREEING | I_WILL_FREE)) &&
+ !atomic_read(&inode->i_count) && inode->i_sb->s_flags & MS_ACTIVE)
+ inode_lru_list_add(inode);
static void inode_lru_list_del(struct inode *inode)
@@ -1390,8 +1403,7 @@ static void iput_final(struct inode *inode)
if (!drop && (sb->s_flags & MS_ACTIVE)) {
inode->i_state |= I_REFERENCED;
- if (!(inode->i_state & (I_DIRTY|I_SYNC)))
- inode_lru_list_add(inode);
+ inode_add_lru(inode);
diff --git a/fs/internal.h b/fs/internal.h
index 371bcc4b1697..52813bd2a229 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -110,6 +110,7 @@ extern int open_check_o_direct(struct file *f);
* inode.c
extern spinlock_t inode_sb_list_lock;
+extern void inode_add_lru(struct inode *inode);
* fs-writeback.c