target: Fall back to vzalloc upon ->sess_cmd_map kzalloc failure

This patch changes transport_alloc_session_tags() to fall back to
use vzalloc when kzalloc fails for big tag_num that end up generating
larger order allocations.

Also use is_vmalloc_addr() in transport_alloc_session_tags() failure
path, and normal transport_free_session() path to determine when
vfree() needs to be called instead of kfree().

v2 changes:
  - Use  __GFP_NOWARN | __GFP_REPEAT for sess_cmd_map kzalloc (mst)

Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Asias He <asias@redhat.com>
Cc: Kent Overstreet <kmo@daterainc.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

1 files changed, 15 insertions, 5 deletions

diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 84747cc1aac0..81e945eefbbd 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -236,17 +236,24 @@ int transport_alloc_session_tags(struct se_session *se_sess,
 {
         int rc;
 
-        se_sess->sess_cmd_map = kzalloc(tag_num * tag_size, GFP_KERNEL);
+        se_sess->sess_cmd_map = kzalloc(tag_num * tag_size,
+                                        GFP_KERNEL | __GFP_NOWARN | __GFP_REPEAT);
         if (!se_sess->sess_cmd_map) {
-                pr_err("Unable to allocate se_sess->sess_cmd_map\n");
-                return -ENOMEM;
+                se_sess->sess_cmd_map = vzalloc(tag_num * tag_size);
+                if (!se_sess->sess_cmd_map) {
+                        pr_err("Unable to allocate se_sess->sess_cmd_map\n");
+                        return -ENOMEM;
+                }
         }
 
         rc = percpu_ida_init(&se_sess->sess_tag_pool, tag_num);
         if (rc < 0) {
                 pr_err("Unable to init se_sess->sess_tag_pool,"
                         " tag_num: %u\n", tag_num);
-                kfree(se_sess->sess_cmd_map);
+                if (is_vmalloc_addr(se_sess->sess_cmd_map))
+                        vfree(se_sess->sess_cmd_map);
+                else
+                        kfree(se_sess->sess_cmd_map);
                 se_sess->sess_cmd_map = NULL;
                 return -ENOMEM;
         }
@@ -412,7 +419,10 @@ void transport_free_session(struct se_session *se_sess)
 {
         if (se_sess->sess_cmd_map) {
                 percpu_ida_destroy(&se_sess->sess_tag_pool);
-                kfree(se_sess->sess_cmd_map);
+                if (is_vmalloc_addr(se_sess->sess_cmd_map))
+                        vfree(se_sess->sess_cmd_map);
+                else
+                        kfree(se_sess->sess_cmd_map);
         }
         kmem_cache_free(se_sess_cache, se_sess);
 }