git.ipfire.org Git - thirdparty/kernel/stable-queue.git/blob

   1 From 311a1bdc44a8e06024df4fd3392be0dfc8298655 Mon Sep 17 00:00:00 2001
   2 From: Waiman Long <longman@redhat.com>
   3 Date: Sun, 4 Aug 2024 21:30:16 -0400
   4 Subject: cgroup/cpuset: Clear effective_xcpus on cpus_allowed clearing only if cpus.exclusive not set
   5
   6 From: Waiman Long <longman@redhat.com>
   7
   8 commit 311a1bdc44a8e06024df4fd3392be0dfc8298655 upstream.
   9
  10 Commit e2ffe502ba45 ("cgroup/cpuset: Add cpuset.cpus.exclusive for
  11 v2") adds a user writable cpuset.cpus.exclusive file for setting
  12 exclusive CPUs to be used for the creation of partitions. Since then
  13 effective_xcpus depends on both the cpuset.cpus and cpuset.cpus.exclusive
  14 setting. If cpuset.cpus.exclusive is set, effective_xcpus will depend
  15 only on cpuset.cpus.exclusive.  When it is not set, effective_xcpus
  16 will be set according to the cpuset.cpus value when the cpuset becomes
  17 a valid partition root.
  18
  19 When cpuset.cpus is being cleared by the user, effective_xcpus should
  20 only be cleared when cpuset.cpus.exclusive is not set. However, that
  21 is not currently the case.
  22
  23   # cd /sys/fs/cgroup/
  24   # mkdir test
  25   # echo +cpuset > cgroup.subtree_control
  26   # cd test
  27   # echo 3 > cpuset.cpus.exclusive
  28   # cat cpuset.cpus.exclusive.effective
  29   3
  30   # echo > cpuset.cpus
  31   # cat cpuset.cpus.exclusive.effective // was cleared
  32
  33 Fix it by clearing effective_xcpus only if cpuset.cpus.exclusive is
  34 not set.
  35
  36 Fixes: e2ffe502ba45 ("cgroup/cpuset: Add cpuset.cpus.exclusive for v2")
  37 Cc: stable@vger.kernel.org # v6.7+
  38 Reported-by: Chen Ridong <chenridong@huawei.com>
  39 Signed-off-by: Waiman Long <longman@redhat.com>
  40 Signed-off-by: Tejun Heo <tj@kernel.org>
  41 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  42 ---
  43  kernel/cgroup/cpuset.c |    3 ++-
  44  1 file changed, 2 insertions(+), 1 deletion(-)
  45
  46 --- a/kernel/cgroup/cpuset.c
  47 +++ b/kernel/cgroup/cpuset.c
  48 @@ -2474,7 +2474,8 @@ static int update_cpumask(struct cpuset
  49          */
  50         if (!*buf) {
  51                 cpumask_clear(trialcs->cpus_allowed);
  52 -               cpumask_clear(trialcs->effective_xcpus);
  53 +               if (cpumask_empty(trialcs->exclusive_cpus))
  54 +                       cpumask_clear(trialcs->effective_xcpus);
  55         } else {
  56                 retval = cpulist_parse(buf, trialcs->cpus_allowed);
  57                 if (retval < 0)