blkcg: use blkg_free() in blkcg_init_queue() failure path

htejun · axboe · commit 994b78327458 · 2015-08-18T15:49:16.000-07:00
When blkcg_init_queue() fails midway after creating a new blkg, it
performs kfree() directly; however, this doesn't free the policy data
areas.  Make it use blkg_free() instead.  In turn, blkg_free() is
updated to handle root request_list special case.

While this fixes a possible memory leak, it's on an unlikely failure
path of an already cold path and the size leaked per occurrence is
miniscule too.  I don't think it needs to be tagged for -stable.

Signed-off-by: Tejun Heo &lt;tj@kernel.org&gt;
Cc: Vivek Goyal &lt;vgoyal@redhat.com&gt;
Signed-off-by: Jens Axboe &lt;axboe@fb.com&gt;
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
@@ -70,7 +70,8 @@ static void blkg_free(struct blkcg_gq *blkg)
 	for (i = 0; i < BLKCG_MAX_POLS; i++)
 		kfree(blkg->pd[i]);
 
-	blk_exit_rl(&blkg->rl);
+	if (blkg->blkcg != &blkcg_root)
+		blk_exit_rl(&blkg->rl);
 	kfree(blkg);
 }
 
@@ -938,7 +939,7 @@ int blkcg_init_queue(struct request_queue *q)
 		radix_tree_preload_end();
 
 	if (IS_ERR(blkg)) {
-		kfree(new_blkg);
+		blkg_free(new_blkg);
 		return PTR_ERR(blkg);
 	}
 

Original file line number	Diff line number	Diff line change
`@@ -70,7 +70,8 @@ static void blkg_free(struct blkcg_gq *blkg)`
`70`	`70`	`for (i = 0; i < BLKCG_MAX_POLS; i++)`
`71`	`71`	`kfree(blkg->pd[i]);`
`72`	`72`
`73`		`- blk_exit_rl(&blkg->rl);`
	`73`	`+ if (blkg->blkcg != &blkcg_root)`
	`74`	`+ blk_exit_rl(&blkg->rl);`
`74`	`75`	`kfree(blkg);`
`75`	`76`	`}`
`76`	`77`
`@@ -938,7 +939,7 @@ int blkcg_init_queue(struct request_queue *q)`
`938`	`939`	`radix_tree_preload_end();`
`939`	`940`
`940`	`941`	`if (IS_ERR(blkg)) {`
`941`		`- kfree(new_blkg);`
	`942`	`+ blkg_free(new_blkg);`
`942`	`943`	`return PTR_ERR(blkg);`
`943`	`944`	`}`
`944`	`945`