[PATCH 0/2] fixes for list_lru

[PATCH 0/2] fixes for list_lru

[Glauber Costa]

Hi Andrew,

I can't find those fixes - or replies to it - anywehere.
Maybe I just forgot to hit send ? If that is the case, sorry
about that.

I am resending just in case. They are supposed to be
folded to their respective patches:
- inode-convert-inode-lru-list-to-generic-lru-list-code.patch
- list_lru-dynamically-adjust-node-arrays.patch

Thanks


Glauber Costa (2):
  inode: move inode to a different list inside lock
  super: fix for destroy lrus

 fs/inode.c       | 2 +-
 fs/super.c       | 3 +++
 fs/xfs/xfs_buf.c | 2 +-
 fs/xfs/xfs_qm.c  | 2 +-
 4 files changed, 6 insertions(+), 3 deletions(-)

-- 
1.8.2.1

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[PATCH 1/2] inode: move inode to a different list inside lock

[Glauber Costa]

When removing an element from the lru, this will be done today after the lock
is released. This is a clear mistake, although we are not sure if the bugs we
are seeing are related to this. All list manipulations are done inside the
lock, and so should this one.

Signed-off-by: Glauber Costa <glommer@openvz.org>
---
 fs/inode.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/inode.c b/fs/inode.c
index a2b49c8..e315c0a 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -735,9 +735,9 @@ inode_lru_isolate(struct list_head *item, spinlock_t *lru_lock, void *arg)
 
 	WARN_ON(inode->i_state & I_NEW);
 	inode->i_state |= I_FREEING;
+	list_move(&inode->i_lru, freeable);
 	spin_unlock(&inode->i_lock);
 
-	list_move(&inode->i_lru, freeable);
 	this_cpu_dec(nr_unused);
 	return LRU_REMOVED;
 }
-- 
1.8.2.1

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[PATCH 2/2] super: fix for destroy lrus

[Glauber Costa]

This patch adds the missing call to list_lru_destroy (spotted by Li Zhong)
and moves the deletion to after the shrinker is unregistered, as correctly
spotted by Dave

Signed-off-by: Glauber Costa <glommer@openvz.org>
---
 fs/super.c       | 3 +++
 fs/xfs/xfs_buf.c | 2 +-
 fs/xfs/xfs_qm.c  | 2 +-
 3 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/fs/super.c b/fs/super.c
index b79e732..09da975 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -328,6 +328,9 @@ void deactivate_locked_super(struct super_block *s)
 
 		/* caches are now gone, we can safely kill the shrinker now */
 		unregister_shrinker(&s->s_shrink);
+		list_lru_destroy(&s->s_dentry_lru);
+		list_lru_destroy(&s->s_inode_lru);
+
 		put_filesystem(fs);
 		put_super(s);
 	} else {
diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index 6c77431..8b2c5aa 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -1591,8 +1591,8 @@ xfs_free_buftarg(
 	struct xfs_mount	*mp,
 	struct xfs_buftarg	*btp)
 {
-	list_lru_destroy(&btp->bt_lru);
 	unregister_shrinker(&btp->bt_shrinker);
+	list_lru_destroy(&btp->bt_lru);
 
 	if (mp->m_flags & XFS_MOUNT_BARRIER)
 		xfs_blkdev_issue_flush(btp);
diff --git a/fs/xfs/xfs_qm.c b/fs/xfs/xfs_qm.c
index c88cb68..1e3d4ed 100644
--- a/fs/xfs/xfs_qm.c
+++ b/fs/xfs/xfs_qm.c
@@ -889,8 +889,8 @@ xfs_qm_destroy_quotainfo(
 	qi = mp->m_quotainfo;
 	ASSERT(qi != NULL);
 
-	list_lru_destroy(&qi->qi_lru);
 	unregister_shrinker(&qi->qi_shrinker);
+	list_lru_destroy(&qi->qi_lru);
 
 	if (qi->qi_uquotaip) {
 		IRELE(qi->qi_uquotaip);
-- 
1.8.2.1

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Re: [PATCH 1/2] inode: move inode to a different list inside lock

[Michal Hocko]

On Wed 26-06-13 02:29:40, Glauber Costa wrote:
> When removing an element from the lru, this will be done today after the lock
> is released. This is a clear mistake, although we are not sure if the bugs we
> are seeing are related to this. All list manipulations are done inside the
> lock, and so should this one.
> 
> Signed-off-by: Glauber Costa <glommer@openvz.org>

Yes this fixed BUG_ONs triggered during my testing (e.g. BUG at mm/list_lru.c:92)
Tested-by: Michal Hocko <mhocko@suse.cz>

> ---
>  fs/inode.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/inode.c b/fs/inode.c
> index a2b49c8..e315c0a 100644
> --- a/fs/inode.c
> +++ b/fs/inode.c
> @@ -735,9 +735,9 @@ inode_lru_isolate(struct list_head *item, spinlock_t *lru_lock, void *arg)
>  
>  	WARN_ON(inode->i_state & I_NEW);
>  	inode->i_state |= I_FREEING;
> +	list_move(&inode->i_lru, freeable);
>  	spin_unlock(&inode->i_lock);
>  
> -	list_move(&inode->i_lru, freeable);
>  	this_cpu_dec(nr_unused);
>  	return LRU_REMOVED;
>  }
> -- 
> 1.8.2.1
> 

-- 
Michal Hocko
SUSE Labs

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