On 7/31/24 23:22, Waiman Long wrote:
On 7/31/24 05:21, Chen Ridong wrote:
After commit 737bb142a00d ("cgroup/cpuset: Make cpuset.cpus.exclusive
independent of cpuset.cpus"), cpuset.cpus.exclusive and cpuset.cpus
became independent. However we found that
cpuset.cpus.exclusive.effective
is cleared when cpuset.cpus is clear. To fix this issue, just remove
xcpus
clearing when cpuset.cpus is being cleared.
It can be reproduced as below:
cd /sys/fs/cgroup/
mkdir test
echo +cpuset > cgroup.subtree_control
cd test
echo 3 > cpuset.cpus.exclusive
cat cpuset.cpus.exclusive.effective
3
echo > cpuset.cpus
cat cpuset.cpus.exclusive.effective // was cleared
Signed-off-by: Chen Ridong <chenridong@xxxxxxxxxx>
---
kernel/cgroup/cpuset.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index a9b6d56eeffa..248c39bebbe9 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -2523,10 +2523,9 @@ static int update_cpumask(struct cpuset *cs,
struct cpuset *trialcs,
* that parsing. The validate_change() call ensures that cpusets
* with tasks have cpus.
*/
- if (!*buf) {
+ if (!*buf)
cpumask_clear(trialcs->cpus_allowed);
- cpumask_clear(trialcs->effective_xcpus);
- } else {
+ else {
retval = cpulist_parse(buf, trialcs->cpus_allowed);
if (retval < 0)
return retval;
Yes, that is a corner case bug that has not been properly handled.
Reviewed-by: Waiman Long <longman@xxxxxxxxxx>
With a second thought, I think we should keep the clearing of
effective_xcpus if exclusive_cpus is empty. IOW
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index 6ba8313f1fc3..2023cd68d9bc 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -2516,7 +2516,8 @@ static int update_cpumask(struct cpuset *cs,
struct cpuset *trialcs,
*/
if (!*buf) {
cpumask_clear(trialcs->cpus_allowed);
- cpumask_clear(trialcs->effective_xcpus);
+ if (cpumask_empty(trialcs->exclusive_cpus))
+ cpumask_clear(trialcs->effective_xcpus);
} else {
retval = cpulist_parse(buf, trialcs->cpus_allowed);
if (retval < 0)
Thanks,
Longman
