Patch "cgroup: set css->id to -1 during init" has been added to the 4.6-stable tree

Patch "cgroup: set css->id to -1 during init" has been added to the 4.6-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    cgroup: set css->id to -1 during init

to the 4.6-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     cgroup-set-css-id-to-1-during-init.patch
and it can be found in the queue-4.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 8fa3b8d689a54d6d04ff7803c724fb7aca6ce98e Mon Sep 17 00:00:00 2001
From: Tejun Heo <tj@kernel.org>
Date: Thu, 26 May 2016 15:42:13 -0400
Subject: cgroup: set css->id to -1 during init

From: Tejun Heo <tj@kernel.org>

commit 8fa3b8d689a54d6d04ff7803c724fb7aca6ce98e upstream.

If percpu_ref initialization fails during css_create(), the free path
can end up trying to free css->id of zero.  As ID 0 is unused, it
doesn't cause a critical breakage but it does trigger a warning
message.  Fix it by setting css->id to -1 from init_and_link_css().

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Wenwei Tao <ww.tao0320@gmail.com>
Fixes: 01e586598b22 ("cgroup: release css->id after css_free")
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 kernel/cgroup.c |    1 +
 1 file changed, 1 insertion(+)

--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -5063,6 +5063,7 @@ static void init_and_link_css(struct cgr
 	memset(css, 0, sizeof(*css));
 	css->cgroup = cgrp;
 	css->ss = ss;
+	css->id = -1;
 	INIT_LIST_HEAD(&css->sibling);
 	INIT_LIST_HEAD(&css->children);
 	css->serial_nr = css_serial_nr_next++;


Patches currently in stable-queue which might be from tj@kernel.org are

queue-4.6/memcg-css_alloc-should-return-an-err_ptr-value-on-error.patch
queue-4.6/memcg-mem_cgroup_migrate-may-be-called-with-irq-disabled.patch
queue-4.6/cgroup-disable-irqs-while-holding-css_set_lock.patch
queue-4.6/cgroup-set-css-id-to-1-during-init.patch
queue-4.6/cgroup-remove-redundant-cleanup-in-css_create.patch
queue-4.6/mm-memcontrol-fix-cgroup-creation-failure-after-many-small-jobs.patch