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Message-ID: <171593317007.10875.3075272533719435489.tip-bot2@tip-bot2>
Date: Fri, 17 May 2024 08:06:10 -0000
From: "tip-bot2 for Cheng Yu" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Qixin Liao <liaoqixin@...wei.com>, Cheng Yu <serein.chengyu@...wei.com>,
Zhang Qiao <zhangqiao22@...wei.com>, Ingo Molnar <mingo@...nel.org>,
Vincent Guittot <vincent.guittot@...aro.org>, x86@...nel.org,
linux-kernel@...r.kernel.org
Subject: [tip: sched/urgent] sched/core: Fix incorrect initialization of the
'burst' parameter in cpu_max_write()
The following commit has been merged into the sched/urgent branch of tip:
Commit-ID: 49217ea147df7647cb89161b805c797487783fc0
Gitweb: https://git.kernel.org/tip/49217ea147df7647cb89161b805c797487783fc0
Author: Cheng Yu <serein.chengyu@...wei.com>
AuthorDate: Wed, 24 Apr 2024 21:24:38 +08:00
Committer: Ingo Molnar <mingo@...nel.org>
CommitterDate: Fri, 17 May 2024 09:53:54 +02:00
sched/core: Fix incorrect initialization of the 'burst' parameter in cpu_max_write()
In the cgroup v2 CPU subsystem, assuming we have a
cgroup named 'test', and 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 find 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, get the burst value directly from tg->cfs_bandwidth.burst.
Fixes: f4183717b370 ("sched/fair: Introduce the burstable CFS controller")
Reported-by: Qixin Liao <liaoqixin@...wei.com>
Signed-off-by: Cheng Yu <serein.chengyu@...wei.com>
Signed-off-by: Zhang Qiao <zhangqiao22@...wei.com>
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Reviewed-by: Vincent Guittot <vincent.guittot@...aro.org>
Tested-by: Vincent Guittot <vincent.guittot@...aro.org>
Link: https://lore.kernel.org/r/20240424132438.514720-1-serein.chengyu@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 1a91438..f88f505 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;
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