blk-cgroup: remove redundant __GFP_NOWARN

Commit 16f5dfb ("gfp: include __GFP_NOWARN in GFP_NOWAIT") made
GFP_NOWAIT implicitly include __GFP_NOWARN.

Therefore, explicit __GFP_NOWARN combined with GFP_NOWAIT (e.g.,
`GFP_NOWAIT | __GFP_NOWARN`) is now redundant.  Let's clean up these
redundant flags across subsystems.

Signed-off-by: Qianfeng Rong <rongqianfeng@vivo.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20250809141358.168781-1-rongqianfeng@vivo.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: qianfengrong

block/blk-cgroup.c

@@ -394,7 +394,7 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg, struct gendisk *disk,
 
 	/* allocate */
 	if (!new_blkg) {
-		new_blkg = blkg_alloc(blkcg, disk, GFP_NOWAIT | __GFP_NOWARN);
+		new_blkg = blkg_alloc(blkcg, disk, GFP_NOWAIT);
 		if (unlikely(!new_blkg)) {
 			ret = -ENOMEM;
 			goto err_put_css;
@@ -1467,7 +1467,7 @@ blkcg_css_alloc(struct cgroup_subsys_state *parent_css)
 
 	spin_lock_init(&blkcg->lock);
 	refcount_set(&blkcg->online_pin, 1);
-	INIT_RADIX_TREE(&blkcg->blkg_tree, GFP_NOWAIT | __GFP_NOWARN);
+	INIT_RADIX_TREE(&blkcg->blkg_tree, GFP_NOWAIT);
 	INIT_HLIST_HEAD(&blkcg->blkg_list);
 #ifdef CONFIG_CGROUP_WRITEBACK
 	INIT_LIST_HEAD(&blkcg->cgwb_list);
@@ -1630,7 +1630,7 @@ int blkcg_activate_policy(struct gendisk *disk, const struct blkcg_policy *pol)
 			pd_prealloc = NULL;
 		} else {
 			pd = pol->pd_alloc_fn(disk, blkg->blkcg,
-					      GFP_NOWAIT | __GFP_NOWARN);
+					      GFP_NOWAIT);
 		}
 
 		if (!pd) {