Re: [PATCH] xfs: handle register_shrinker error

Michal Hocko
2017-11-23T16:11:41Z

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@lst.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?
---
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;
}

--
Michal Hocko
SUSE Labs