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Date:   Fri, 24 Nov 2017 09:00:46 +1100
From:   Dave Chinner <david@...morbit.com>
To:     Michal Hocko <mhocko@...nel.org>
Cc:     Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
        hch@...radead.org, darrick.wong@...cle.com,
        linux-xfs@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] xfs: handle register_shrinker error

On Thu, Nov 23, 2017 at 05:11:37PM +0100, Michal Hocko wrote:
> On Fri 24-11-17 01:01:10, Tetsuo Handa wrote:
> > Michal Hocko wrote:
> > > On Thu 23-11-17 05:26:33, Christoph Hellwig wrote:
> > > > Looks good,
> > > > 
> > > > Reviewed-by: Christoph Hellwig <hch@....de>
> > > 
> > > Thanks!
> > > 
> > > > I can take a stab at the quota one.
> > > 
> > > That would be really great!
> > > 
> > Again, it does not look good. Since kmem_free() does only kvfree(),
> > nothing will release memory allocated by list_lru_init().
> 
> Hmm, you are right. I have (blindly) followed the current code flow
> which is wrong as well. The following should do the trick. Should I
> split that into two patches?

One is fine by me - if we're need to backport one fix, then we need
to backport both :/

> ---
> diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
> index dd0e18af990c..4c6e86d861fd 100644
> --- a/fs/xfs/xfs_buf.c
> +++ b/fs/xfs/xfs_buf.c
> @@ -1815,25 +1815,27 @@ xfs_alloc_buftarg(
>  	btp->bt_daxdev = dax_dev;
>  
>  	if (xfs_setsize_buftarg_early(btp, bdev))
> -		goto error;
> +		goto error_free;
>  
>  	if (list_lru_init(&btp->bt_lru))
> -		goto error;
> +		goto error_free;
>  
>  	if (percpu_counter_init(&btp->bt_io_count, 0, GFP_KERNEL))
> -		goto error;
> +		goto error_lru;
>  
>  	btp->bt_shrinker.count_objects = xfs_buftarg_shrink_count;
>  	btp->bt_shrinker.scan_objects = xfs_buftarg_shrink_scan;
>  	btp->bt_shrinker.seeks = DEFAULT_SEEKS;
>  	btp->bt_shrinker.flags = SHRINKER_NUMA_AWARE;
> -	if (register_shrinker(&btp->bt_shrinker)) {
> -		percpu_counter_destroy(&btp->bt_io_count);
> -		goto error;
> -	}
> +	if (register_shrinker(&btp->bt_shrinker))
> +		goto error_pcpu;
>  	return btp;
>  
> -error:
> +error_pcpu:
> +	percpu_counter_destroy(&btp->bt_io_count);
> +error_lru:
> +	list_lru_destroy(&btp->bt_lru);
> +error_free:
>  	kmem_free(btp);
>  	return NULL;

That should do the trick.

Acked-by: Dave Chinner <dchinner@...hat.com>

Cheers,

Dave.
-- 
Dave Chinner
david@...morbit.com

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