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cgroup: fix bogus kernel warnings when cgroup_create() failed

PATCH Applied Li Zefan 2 participants 2 messages Jan 21, 2013 – Jan 23, 2013 cgroup

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Li Zefan

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#0 lore raw

PATCH 1/1 cgroup: fix bogus kernel warnings when cgroup_create() failed

If cgroup_create() failed and cgroup_destroy_locked() is called to do cleanup, we'll see a bunch of warnings:

cgroup_addrm_files: failed to remove 2MB.limit_in_bytes, err=-2
cgroup_addrm_files: failed to remove 2MB.usage_in_bytes, err=-2
cgroup_addrm_files: failed to remove 2MB.max_usage_in_bytes, err=-2
cgroup_addrm_files: failed to remove 2MB.failcnt, err=-2
cgroup_addrm_files: failed to remove prioidx, err=-2
cgroup_addrm_files: failed to remove ifpriomap, err=-2
...

We failed to remove those files, because cgroup_create() has failed before creating those cgroup files.

To fix this, we simply don't warn if cgroup_rm_file() can't find the cft entry.

Signed-off-by Li Zefan <[email protected]>
---
 kernel/cgroup.c | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)
kernel/cgroup.c +12 -9
index 77ab520..1db2438 100644
@@ -928,13 +928,17 @@ static void remove_dir(struct dentry *d)
 	dput(parent);
 }
 
-static int cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft)
+static void cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft)
 {
 	struct cfent *cfe;
 
 	lockdep_assert_held(&cgrp->dentry->d_inode->i_mutex);
 	lockdep_assert_held(&cgroup_mutex);
 
+	/*
+	 * If we're doing cleanup due to failure of cgroup_create(),
+	 * the corresponding @cfe may not exist.
+	 */
 	list_for_each_entry(cfe, &cgrp->files, node) {
 		struct dentry *d = cfe->dentry;
 

@@ -947,9 +951,8 @@ static int cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft)
 		list_del_init(&cfe->node);
 		dput(d);
 
-		return 0;
+		break;
 	}
-	return -ENOENT;
 }
 
 /**

@@ -2765,14 +2768,14 @@ static int cgroup_addrm_files(struct cgroup *cgrp, struct cgroup_subsys *subsys,
 		if ((cft->flags & CFTYPE_ONLY_ON_ROOT) && cgrp->parent)
 			continue;
 
-		if (is_add)
+		if (is_add) {
 			err = cgroup_add_file(cgrp, subsys, cft);
-		else
-			err = cgroup_rm_file(cgrp, cft);
-		if (err) {
-			pr_warning("cgroup_addrm_files: failed to %s %s, err=%d\n",
-				   is_add ? "add" : "remove", cft->name, err);
+			if (err)
+				pr_warn("cgroup_addrm_files: failed to add %s, err=%d\n",
+					cft->name, err);
 			ret = err;
+		} else {
+			cgroup_rm_file(cgrp, cft);
 		}
 	}
 	return ret;
Signature · 1 line
1.8.0.2
maintainer Applied
#1 lore raw
Quoted 11 lines · Li Zefan

If cgroup_create() failed and cgroup_destroy_locked() is called to do cleanup, we'll see a bunch of warnings:

cgroup_addrm_files: failed to remove 2MB.limit_in_bytes, err=-2
cgroup_addrm_files: failed to remove 2MB.usage_in_bytes, err=-2
cgroup_addrm_files: failed to remove 2MB.max_usage_in_bytes, err=-2
cgroup_addrm_files: failed to remove 2MB.failcnt, err=-2
cgroup_addrm_files: failed to remove prioidx, err=-2
cgroup_addrm_files: failed to remove ifpriomap, err=-2
...

Quoted 7 lines

We failed to remove those files, because cgroup_create() has failed before creating those cgroup files.

To fix this, we simply don't warn if cgroup_rm_file() can't find the cft entry.

Signed-off-by Li Zefan <[email protected]>

Applied to cgroup/for-3.9. Thanks!

Signature · 1 line
tejun