[8/8] inode: don't softlockup when evicting inodes

Commit Message

Josef Bacik June 11, 2015, 7:41 p.m. UTC

On a box with a lot of ram (148gb) I can make the box softlockup after running
an fs_mark job that creates hundreds of millions of empty files.  This is
because we never generate enough memory pressure to keep the number of inodes on
our unused list low, so when we go to unmount we have to evict ~100 million
inodes.  This makes one processor a very unhappy person, so add a cond_resched()
in dispose_list() and if we need a resched when processing the s_inodes list do
that and run dispose_list() on what we've currently culled.  Thanks,

Signed-off-by: Josef Bacik <[e-mail]>
---
 fs/inode.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

Comments

Jan Kara June 15, 2015, 2:16 p.m. UTC | #1

On Thu 11-06-15 15:41:13, Josef Bacik wrote:
> On a box with a lot of ram (148gb) I can make the box softlockup after running
> an fs_mark job that creates hundreds of millions of empty files.  This is
> because we never generate enough memory pressure to keep the number of inodes on
> our unused list low, so when we go to unmount we have to evict ~100 million
> inodes.  This makes one processor a very unhappy person, so add a cond_resched()
> in dispose_list() and if we need a resched when processing the s_inodes list do
> that and run dispose_list() on what we've currently culled.  Thanks,
> 
> Signed-off-by: Josef Bacik <[e-mail]>
  Looks good. You can add:
Reviewed-by: Jan Kara <[e-mail]>

								Honza
> ---
>  fs/inode.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/fs/inode.c b/fs/inode.c
> index d1e6598..53a1224 100644
> --- a/fs/inode.c
> +++ b/fs/inode.c
> @@ -574,6 +574,7 @@ static void dispose_list(struct list_head *head)
>  		list_del_init(&inode->i_lru);
>  
>  		evict(inode);
> +		cond_resched();
>  	}
>  }
>  
> @@ -591,6 +592,7 @@ void evict_inodes(struct super_block *sb)
>  	struct inode *inode, *next;
>  	LIST_HEAD(dispose);
>  
> +again:
>  	spin_lock(&sb->s_inode_list_lock);
>  	list_for_each_entry_safe(inode, next, &sb->s_inodes, i_sb_list) {
>  		if (atomic_read(&inode->i_count))
> @@ -606,6 +608,18 @@ void evict_inodes(struct super_block *sb)
>  		inode_lru_list_del(inode);
>  		spin_unlock(&inode->i_lock);
>  		list_add(&inode->i_lru, &dispose);
> +
> +		/*
> +		 * We can have a ton of inodes to evict at unmount time given
> +		 * enough memory, check to see if we need to go to sleep for a
> +		 * bit so we don't livelock.
> +		 */
> +		if (need_resched()) {
> +			spin_unlock(&sb->s_inode_list_lock);
> +			cond_resched();
> +			dispose_list(&dispose);
> +			goto again;
> +		}
>  	}
>  	spin_unlock(&sb->s_inode_list_lock);
>  
> -- 
> 2.1.0
>

Patch

diff --git a/fs/inode.c b/fs/inode.c
index d1e6598..53a1224 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -574,6 +574,7 @@  static void dispose_list(struct list_head *head)
 		list_del_init(&inode->i_lru);
 
 		evict(inode);
+		cond_resched();
 	}
 }
 
@@ -591,6 +592,7 @@  void evict_inodes(struct super_block *sb)
 	struct inode *inode, *next;
 	LIST_HEAD(dispose);
 
+again:
 	spin_lock(&sb->s_inode_list_lock);
 	list_for_each_entry_safe(inode, next, &sb->s_inodes, i_sb_list) {
 		if (atomic_read(&inode->i_count))
@@ -606,6 +608,18 @@  void evict_inodes(struct super_block *sb)
 		inode_lru_list_del(inode);
 		spin_unlock(&inode->i_lock);
 		list_add(&inode->i_lru, &dispose);
+
+		/*
+		 * We can have a ton of inodes to evict at unmount time given
+		 * enough memory, check to see if we need to go to sleep for a
+		 * bit so we don't livelock.
+		 */
+		if (need_resched()) {
+			spin_unlock(&sb->s_inode_list_lock);
+			cond_resched();
+			dispose_list(&dispose);
+			goto again;
+		}
 	}
 	spin_unlock(&sb->s_inode_list_lock);