Messages in this thread Patch in this message | | | From | Cheng Yu <> | Subject | [PATCH] sched/core: fix incorrect parameter burst in cpu_max_write() | Date | Wed, 24 Apr 2024 21:24:38 +0800 |
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In the cgroup v2 cpu subsystem, assuming we have a cgroup named test, we set cpu.max and cpu.max.burst: # echo 1000000 > /sys/fs/cgroup/test/cpu.max # echo 1000000 > /sys/fs/cgroup/test/cpu.max.burst then we check cpu.max and cpu.max.burst: # cat /sys/fs/cgroup/test/cpu.max 1000000 100000 # cat /sys/fs/cgroup/test/cpu.max.burst 1000000
Next we set cpu.max again and check cpu.max and cpu.max.burst: # echo 2000000 > /sys/fs/cgroup/test/cpu.max # cat /sys/fs/cgroup/test/cpu.max 2000000 100000 # cat /sys/fs/cgroup/test/cpu.max.burst 1000 we found that the cpu.max.burst value changed unexpectedly.
In cpu_max_write(), the unit of the burst value returned by tg_get_cfs_burst() is microseconds, while in cpu_max_write(), the burst unit used for calculation should be nanoseconds, which leads to the bug.
To fix it, we get the burst value directly from tg->cfs_bandwidth.burst.
Reported-by: Qixin Liao <liaoqixin@huawei.com> Fixes: f4183717b370 ("sched/fair: Introduce the burstable CFS controller") Signed-off-by: Cheng Yu <serein.chengyu@huawei.com> Signed-off-by: Zhang Qiao <zhangqiao22@huawei.com> --- kernel/sched/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 7019a40457a6..d211d40a2edc 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -11402,7 +11402,7 @@ static ssize_t cpu_max_write(struct kernfs_open_file *of, { struct task_group *tg = css_tg(of_css(of)); u64 period = tg_get_cfs_period(tg); - u64 burst = tg_get_cfs_burst(tg); + u64 burst = tg->cfs_bandwidth.burst; u64 quota; int ret; -- 2.25.1
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