[lustre-devel] [PATCH 20/28] lustre: lov: use GFP_NOFS to allocate lo_entries.

[NeilBrown]

lo_type_guard is taken during memory reclaim:

               -> #0 (&lov->lo_type_guard){++++}:
[  576.552501]        down_read+0x27/0x7c
[  576.553072]        lov_object_delete+0xd5/0x1bb
[  576.553836]        lu_object_free+0x5f/0x111
[  576.554524]        lu_object_put+0x313/0x337
[  576.555267]        cl_inode_fini+0x158/0x1ac
[  576.555898]        ll_delete_inode+0xcc/0xd5
[  576.556572]        evict+0xb4/0x166
[  576.557162]        dispose_list+0x30/0x34
[  576.557834]        prune_icache_sb+0x55/0x73
[  576.558465]        super_cache_scan+0x122/0x16d
[  576.559138]        shrink_slab.part.22.constprop.37+0x27b/0x414
[  576.560059]        shrink_node+0x8d/0x1b3

and lov_init_composite is called while lo_type_guard is held:

[  576.540707]        lov_init_composite+0xff/0xc5f
[  576.541496]        lov_conf_set+0x4cf/0x658
[  576.542179]        cl_conf_set+0x49/0x58
[  576.542790]        cl_file_inode_init+0x21a/0x2b8
[  576.543564]        ll_update_inode+0x4e/0xea5
[  576.544277]        ll_iget+0x112/0x1bf
[  576.544871]        ll_prep_inode+0x242/0x43d
[  576.545541]        ll_lookup_it_finish+0xcf/0x51d
[  576.546308]        ll_lookup_it+0x52e/0x5fc
[  576.546976]        ll_atomic_open+0x1ce/0x74f
[  576.547666]        lookup_open+0x298/0x526
[  576.548325]        path_openat+0x29a/0x7d3
[  576.548917]        do_filp_open+0x57/0xc1
[  576.549539]        do_sys_open+0x137/0x1e7

so it is not safe to use GFP_KERNEL in lov_init_composite().

Use GFP_NOFS instead.

Signed-off-by: NeilBrown <neilb at suse.com>
---
 drivers/staging/lustre/lustre/lov/lov_object.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/staging/lustre/lustre/lov/lov_object.c b/drivers/staging/lustre/lustre/lov/lov_object.c
index 2058275d1cdc..eee89ce97703 100644
--- a/drivers/staging/lustre/lustre/lov/lov_object.c
+++ b/drivers/staging/lustre/lustre/lov/lov_object.c
@@ -302,7 +302,7 @@ static int lov_init_composite(const struct lu_env *env, struct lov_device *dev,
 	comp->lo_entry_count = entry_count;
 
 	comp->lo_entries = kcalloc(entry_count, sizeof(*comp->lo_entries),
-				   GFP_KERNEL);
+				   GFP_NOFS);
 	if (!comp->lo_entries)
 		return -ENOMEM;