[PATCH v2] xfs: handle register_shrinker error

[Michal Hocko]

On Fri 24-11-17 09:00:46, Dave Chinner wrote:
> 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@xxxxxx>
> > > > 
> > > > 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 :/

OK

> > ---
> > 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@xxxxxxxxxx>

Thanks. Updated patch below
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