2022-10-08 03:22:45

by Lin Shengwang

[permalink] [raw]
Subject: [PATCH -next] sched/core: Fix the bug that traversal in sched_group_cookie_match is wrong

In commit 97886d9dcd86 ("sched: Migration changes for core scheduling"),
sched_group_cookie_match() was added to help finding cookie matched
group, but was inconsistent with the actual purpose.

Using cpu_rq(cpu) instead of rq to fix the bug.

Fixes: 97886d9dcd86 ("sched: Migration changes for core scheduling")
Signed-off-by: Lin Shengwang <[email protected]>
---
kernel/sched/sched.h | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 23c6f9f42ba1..1ba602139840 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1182,6 +1182,14 @@ static inline bool is_migration_disabled(struct task_struct *p)
#endif
}

+DECLARE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
+
+#define cpu_rq(cpu) (&per_cpu(runqueues, (cpu)))
+#define this_rq() this_cpu_ptr(&runqueues)
+#define task_rq(p) cpu_rq(task_cpu(p))
+#define cpu_curr(cpu) (cpu_rq(cpu)->curr)
+#define raw_rq() raw_cpu_ptr(&runqueues)
+
struct sched_group;
#ifdef CONFIG_SCHED_CORE
static inline struct cpumask *sched_group_span(struct sched_group *sg);
@@ -1269,7 +1277,7 @@ static inline bool sched_group_cookie_match(struct rq *rq,
return true;

for_each_cpu_and(cpu, sched_group_span(group), p->cpus_ptr) {
- if (sched_core_cookie_match(rq, p))
+ if (sched_core_cookie_match(cpu_rq(cpu), p))
return true;
}
return false;
@@ -1384,14 +1392,6 @@ static inline void update_idle_core(struct rq *rq)
static inline void update_idle_core(struct rq *rq) { }
#endif

-DECLARE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
-
-#define cpu_rq(cpu) (&per_cpu(runqueues, (cpu)))
-#define this_rq() this_cpu_ptr(&runqueues)
-#define task_rq(p) cpu_rq(task_cpu(p))
-#define cpu_curr(cpu) (cpu_rq(cpu)->curr)
-#define raw_rq() raw_cpu_ptr(&runqueues)
-
#ifdef CONFIG_FAIR_GROUP_SCHED
static inline struct task_struct *task_of(struct sched_entity *se)
{
--
2.17.1


2022-10-10 01:39:12

by Li, Aubrey

[permalink] [raw]
Subject: Re: [PATCH -next] sched/core: Fix the bug that traversal in sched_group_cookie_match is wrong

On 10/8/22 10:27, Lin Shengwang wrote:
> In commit 97886d9dcd86 ("sched: Migration changes for core scheduling"),
> sched_group_cookie_match() was added to help finding cookie matched
> group, but was inconsistent with the actual purpose.
>
> Using cpu_rq(cpu) instead of rq to fix the bug.
>
> Fixes: 97886d9dcd86 ("sched: Migration changes for core scheduling")
> Signed-off-by: Lin Shengwang <[email protected]>
> ---
> kernel/sched/sched.h | 18 +++++++++---------
> 1 file changed, 9 insertions(+), 9 deletions(-)
>
> diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
> index 23c6f9f42ba1..1ba602139840 100644
> --- a/kernel/sched/sched.h
> +++ b/kernel/sched/sched.h
> @@ -1182,6 +1182,14 @@ static inline bool is_migration_disabled(struct task_struct *p)
> #endif
> }
>
> +DECLARE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
> +
> +#define cpu_rq(cpu) (&per_cpu(runqueues, (cpu)))
> +#define this_rq() this_cpu_ptr(&runqueues)
> +#define task_rq(p) cpu_rq(task_cpu(p))
> +#define cpu_curr(cpu) (cpu_rq(cpu)->curr)
> +#define raw_rq() raw_cpu_ptr(&runqueues)
> +
> struct sched_group;
> #ifdef CONFIG_SCHED_CORE
> static inline struct cpumask *sched_group_span(struct sched_group *sg);
> @@ -1269,7 +1277,7 @@ static inline bool sched_group_cookie_match(struct rq *rq,
> return true;
>
> for_each_cpu_and(cpu, sched_group_span(group), p->cpus_ptr) {
> - if (sched_core_cookie_match(rq, p))
> + if (sched_core_cookie_match(cpu_rq(cpu), p))> return true;
> }
> return false;
This looks a proper fix to me. Thanks!

-Aubrey

2022-10-10 07:58:10

by Peter Zijlstra

[permalink] [raw]
Subject: Re: [PATCH -next] sched/core: Fix the bug that traversal in sched_group_cookie_match is wrong

On Sat, Oct 08, 2022 at 10:27:09AM +0800, Lin Shengwang wrote:
> In commit 97886d9dcd86 ("sched: Migration changes for core scheduling"),
> sched_group_cookie_match() was added to help finding cookie matched
> group, but was inconsistent with the actual purpose.
>
> Using cpu_rq(cpu) instead of rq to fix the bug.
>
> Fixes: 97886d9dcd86 ("sched: Migration changes for core scheduling")
> Signed-off-by: Lin Shengwang <[email protected]>
> ---
> kernel/sched/sched.h | 18 +++++++++---------
> 1 file changed, 9 insertions(+), 9 deletions(-)
>
> diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
> index 23c6f9f42ba1..1ba602139840 100644
> --- a/kernel/sched/sched.h
> +++ b/kernel/sched/sched.h

> @@ -1269,7 +1277,7 @@ static inline bool sched_group_cookie_match(struct rq *rq,
> return true;
>
> for_each_cpu_and(cpu, sched_group_span(group), p->cpus_ptr) {
> - if (sched_core_cookie_match(rq, p))
> + if (sched_core_cookie_match(cpu_rq(cpu), p))
> return true;

Urgh.. Thanks!

Subject: [tip: sched/urgent] sched/core: Fix comparison in sched_group_cookie_match()

The following commit has been merged into the sched/urgent branch of tip:

Commit-ID: e705968dd687574b6ca3ebe772683d5642759132
Gitweb: https://git.kernel.org/tip/e705968dd687574b6ca3ebe772683d5642759132
Author: Lin Shengwang <[email protected]>
AuthorDate: Sat, 08 Oct 2022 10:27:09 +08:00
Committer: Peter Zijlstra <[email protected]>
CommitterDate: Mon, 17 Oct 2022 16:41:24 +02:00

sched/core: Fix comparison in sched_group_cookie_match()

In commit 97886d9dcd86 ("sched: Migration changes for core scheduling"),
sched_group_cookie_match() was added to help determine if a cookie
matches the core state.

However, while it iterates the SMT group, it fails to actually use the
RQ for each of the CPUs iterated, use cpu_rq(cpu) instead of rq to fix
things.

Fixes: 97886d9dcd86 ("sched: Migration changes for core scheduling")
Signed-off-by: Lin Shengwang <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]
---
kernel/sched/sched.h | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 1644242..0d08511 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1182,6 +1182,14 @@ static inline bool is_migration_disabled(struct task_struct *p)
#endif
}

+DECLARE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
+
+#define cpu_rq(cpu) (&per_cpu(runqueues, (cpu)))
+#define this_rq() this_cpu_ptr(&runqueues)
+#define task_rq(p) cpu_rq(task_cpu(p))
+#define cpu_curr(cpu) (cpu_rq(cpu)->curr)
+#define raw_rq() raw_cpu_ptr(&runqueues)
+
struct sched_group;
#ifdef CONFIG_SCHED_CORE
static inline struct cpumask *sched_group_span(struct sched_group *sg);
@@ -1269,7 +1277,7 @@ static inline bool sched_group_cookie_match(struct rq *rq,
return true;

for_each_cpu_and(cpu, sched_group_span(group), p->cpus_ptr) {
- if (sched_core_cookie_match(rq, p))
+ if (sched_core_cookie_match(cpu_rq(cpu), p))
return true;
}
return false;
@@ -1384,14 +1392,6 @@ static inline void update_idle_core(struct rq *rq)
static inline void update_idle_core(struct rq *rq) { }
#endif

-DECLARE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
-
-#define cpu_rq(cpu) (&per_cpu(runqueues, (cpu)))
-#define this_rq() this_cpu_ptr(&runqueues)
-#define task_rq(p) cpu_rq(task_cpu(p))
-#define cpu_curr(cpu) (cpu_rq(cpu)->curr)
-#define raw_rq() raw_cpu_ptr(&runqueues)
-
#ifdef CONFIG_FAIR_GROUP_SCHED
static inline struct task_struct *task_of(struct sched_entity *se)
{