cgroup: fix idr_preload usage

It does not make much sense to call idr_preload with the same gfp mask
as the following idr_alloc, but this is what we do in cgroup_idr_alloc.
This patch fixes the idr_preload usage by making cgroup_idr_alloc call
idr_alloc w/o __GFP_WAIT. Since it is now safe to call cgroup_idr_alloc
with GFP_KERNEL, the patch also fixes all its callers appropriately.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index a59dd1a6b74a80db6b1568951c66434ec46e66e0..97e2da0d3b2788961cb4d56194ce260d4ac60367 100644 (file)
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -210,7 +210,7 @@ static int cgroup_idr_alloc(struct idr *idr, void *ptr, int start, int end,
 
        idr_preload(gfp_mask);
        spin_lock_bh(&cgroup_idr_lock);
-       ret = idr_alloc(idr, ptr, start, end, gfp_mask);
+       ret = idr_alloc(idr, ptr, start, end, gfp_mask & ~__GFP_WAIT);
        spin_unlock_bh(&cgroup_idr_lock);
        idr_preload_end();
        return ret;
@@ -1669,7 +1669,7 @@ static int cgroup_setup_root(struct cgroup_root *root, unsigned long ss_mask)
 
        lockdep_assert_held(&cgroup_mutex);
 
-       ret = cgroup_idr_alloc(&root->cgroup_idr, root_cgrp, 1, 2, GFP_NOWAIT);
+       ret = cgroup_idr_alloc(&root->cgroup_idr, root_cgrp, 1, 2, GFP_KERNEL);
        if (ret < 0)
                goto out;
        root_cgrp->id = ret;
@@ -4582,7 +4582,7 @@ static int create_css(struct cgroup *cgrp, struct cgroup_subsys *ss,
        if (err)
                goto err_free_css;
 
-       err = cgroup_idr_alloc(&ss->css_idr, NULL, 2, 0, GFP_NOWAIT);
+       err = cgroup_idr_alloc(&ss->css_idr, NULL, 2, 0, GFP_KERNEL);
        if (err < 0)
                goto err_free_percpu_ref;
        css->id = err;
@@ -4659,7 +4659,7 @@ static int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name,
         * Temporarily set the pointer to NULL, so idr_find() won't return
         * a half-baked cgroup.
         */
-       cgrp->id = cgroup_idr_alloc(&root->cgroup_idr, NULL, 2, 0, GFP_NOWAIT);
+       cgrp->id = cgroup_idr_alloc(&root->cgroup_idr, NULL, 2, 0, GFP_KERNEL);
        if (cgrp->id < 0) {
                ret = -ENOMEM;
                goto out_cancel_ref;