* [PATCH linux-next] cgroup: fix suspicious rcu_dereference_check() usage warning
@ 2022-03-05 3:41 Chengming Zhou
[not found] ` <CGME20220309071027eucas1p1f066b42f49e524404d898929b60b344f@eucas1p1.samsung.com>
` (3 more replies)
0 siblings, 4 replies; 7+ messages in thread
From: Chengming Zhou @ 2022-03-05 3:41 UTC (permalink / raw)
To: tj, lizefan.x, hannes, peterz
Cc: cgroups, linux-kernel, songmuchun, Chengming Zhou,
Linux Kernel Functional Testing, syzbot+16e3f2c77e7c5a0113f9,
Zhouyi Zhou
task_css_set_check() will use rcu_dereference_check() to check for
rcu_read_lock_held() on the read-side, which is not true after commit
dc6e0818bc9a ("sched/cpuacct: Optimize away RCU read lock"). This
commit drop explicit rcu_read_lock(), change to RCU-sched read-side
critical section. So fix the RCU warning by adding check for
rcu_read_lock_sched_held().
Fixes: dc6e0818bc9a ("sched/cpuacct: Optimize away RCU read lock")
Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
Reported-by: syzbot+16e3f2c77e7c5a0113f9@syzkaller.appspotmail.com
Tested-by: Zhouyi Zhou <zhouzhouyi@gmail.com>
Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
---
include/linux/cgroup.h | 1 +
1 file changed, 1 insertion(+)
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 1e356c222756..0d1ada8968d7 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -450,6 +450,7 @@ extern struct mutex cgroup_mutex;
extern spinlock_t css_set_lock;
#define task_css_set_check(task, __c) \
rcu_dereference_check((task)->cgroups, \
+ rcu_read_lock_sched_held() || \
lockdep_is_held(&cgroup_mutex) || \
lockdep_is_held(&css_set_lock) || \
((task)->flags & PF_EXITING) || (__c))
--
2.20.1
^ permalink raw reply related [flat|nested] 7+ messages in thread[parent not found: <CGME20220309071027eucas1p1f066b42f49e524404d898929b60b344f@eucas1p1.samsung.com>]
* Re: [PATCH linux-next] cgroup: fix suspicious rcu_dereference_check() usage warning
[not found] ` <CGME20220309071027eucas1p1f066b42f49e524404d898929b60b344f@eucas1p1.samsung.com>
@ 2022-03-09 7:10 ` Marek Szyprowski
0 siblings, 0 replies; 7+ messages in thread
From: Marek Szyprowski @ 2022-03-09 7:10 UTC (permalink / raw)
To: Chengming Zhou, tj, lizefan.x, hannes, peterz
Cc: cgroups, linux-kernel, songmuchun,
Linux Kernel Functional Testing, syzbot+16e3f2c77e7c5a0113f9,
Zhouyi Zhou
On 05.03.2022 04:41, Chengming Zhou wrote:
> task_css_set_check() will use rcu_dereference_check() to check for
> rcu_read_lock_held() on the read-side, which is not true after commit
> dc6e0818bc9a ("sched/cpuacct: Optimize away RCU read lock"). This
> commit drop explicit rcu_read_lock(), change to RCU-sched read-side
> critical section. So fix the RCU warning by adding check for
> rcu_read_lock_sched_held().
>
> Fixes: dc6e0818bc9a ("sched/cpuacct: Optimize away RCU read lock")
> Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
> Reported-by: syzbot+16e3f2c77e7c5a0113f9@syzkaller.appspotmail.com
> Tested-by: Zhouyi Zhou <zhouzhouyi@gmail.com>
> Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
Right, this fixes the issue I've reported here:
https://lore.kernel.org/all/f4bc652b-115f-35b5-91db-bad3b30fed9b@samsung.com/
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
> ---
> include/linux/cgroup.h | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
> index 1e356c222756..0d1ada8968d7 100644
> --- a/include/linux/cgroup.h
> +++ b/include/linux/cgroup.h
> @@ -450,6 +450,7 @@ extern struct mutex cgroup_mutex;
> extern spinlock_t css_set_lock;
> #define task_css_set_check(task, __c) \
> rcu_dereference_check((task)->cgroups, \
> + rcu_read_lock_sched_held() || \
> lockdep_is_held(&cgroup_mutex) || \
> lockdep_is_held(&css_set_lock) || \
> ((task)->flags & PF_EXITING) || (__c))
Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH linux-next] cgroup: fix suspicious rcu_dereference_check() usage warning
2022-03-05 3:41 [PATCH linux-next] cgroup: fix suspicious rcu_dereference_check() usage warning Chengming Zhou
[not found] ` <CGME20220309071027eucas1p1f066b42f49e524404d898929b60b344f@eucas1p1.samsung.com>
@ 2022-03-09 18:10 ` Tejun Heo
2022-03-12 12:19 ` Peter Zijlstra
2022-03-12 12:37 ` [tip: sched/core] cgroup: Fix " tip-bot2 for Chengming Zhou
3 siblings, 0 replies; 7+ messages in thread
From: Tejun Heo @ 2022-03-09 18:10 UTC (permalink / raw)
To: Chengming Zhou
Cc: lizefan.x, hannes, peterz, cgroups, linux-kernel, songmuchun,
Linux Kernel Functional Testing, syzbot+16e3f2c77e7c5a0113f9,
Zhouyi Zhou
On Sat, Mar 05, 2022 at 11:41:03AM +0800, Chengming Zhou wrote:
> task_css_set_check() will use rcu_dereference_check() to check for
> rcu_read_lock_held() on the read-side, which is not true after commit
> dc6e0818bc9a ("sched/cpuacct: Optimize away RCU read lock"). This
> commit drop explicit rcu_read_lock(), change to RCU-sched read-side
> critical section. So fix the RCU warning by adding check for
> rcu_read_lock_sched_held().
>
> Fixes: dc6e0818bc9a ("sched/cpuacct: Optimize away RCU read lock")
> Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
> Reported-by: syzbot+16e3f2c77e7c5a0113f9@syzkaller.appspotmail.com
> Tested-by: Zhouyi Zhou <zhouzhouyi@gmail.com>
> Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
> ---
> include/linux/cgroup.h | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
> index 1e356c222756..0d1ada8968d7 100644
> --- a/include/linux/cgroup.h
> +++ b/include/linux/cgroup.h
> @@ -450,6 +450,7 @@ extern struct mutex cgroup_mutex;
> extern spinlock_t css_set_lock;
> #define task_css_set_check(task, __c) \
> rcu_dereference_check((task)->cgroups, \
> + rcu_read_lock_sched_held() || \
> lockdep_is_held(&cgroup_mutex) || \
> lockdep_is_held(&css_set_lock) || \
> ((task)->flags & PF_EXITING) || (__c))
Acked-by: Tejun Heo <tj@kernel.org>
Thanks.
--
tejun
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [PATCH linux-next] cgroup: fix suspicious rcu_dereference_check() usage warning
2022-03-05 3:41 [PATCH linux-next] cgroup: fix suspicious rcu_dereference_check() usage warning Chengming Zhou
[not found] ` <CGME20220309071027eucas1p1f066b42f49e524404d898929b60b344f@eucas1p1.samsung.com>
2022-03-09 18:10 ` Tejun Heo
@ 2022-03-12 12:19 ` Peter Zijlstra
2022-03-12 13:34 ` Peter Zijlstra
2022-03-12 12:37 ` [tip: sched/core] cgroup: Fix " tip-bot2 for Chengming Zhou
3 siblings, 1 reply; 7+ messages in thread
From: Peter Zijlstra @ 2022-03-12 12:19 UTC (permalink / raw)
To: Chengming Zhou
Cc: tj, lizefan.x, hannes, cgroups, linux-kernel, songmuchun,
Linux Kernel Functional Testing, syzbot+16e3f2c77e7c5a0113f9,
Zhouyi Zhou
On Sat, Mar 05, 2022 at 11:41:03AM +0800, Chengming Zhou wrote:
> task_css_set_check() will use rcu_dereference_check() to check for
> rcu_read_lock_held() on the read-side, which is not true after commit
> dc6e0818bc9a ("sched/cpuacct: Optimize away RCU read lock"). This
> commit drop explicit rcu_read_lock(), change to RCU-sched read-side
> critical section. So fix the RCU warning by adding check for
> rcu_read_lock_sched_held().
>
> Fixes: dc6e0818bc9a ("sched/cpuacct: Optimize away RCU read lock")
> Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
> Reported-by: syzbot+16e3f2c77e7c5a0113f9@syzkaller.appspotmail.com
> Tested-by: Zhouyi Zhou <zhouzhouyi@gmail.com>
> Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
Thanks, I'll go stick this in sched/core so it's in the same branch that
caused the problem.
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [PATCH linux-next] cgroup: fix suspicious rcu_dereference_check() usage warning
2022-03-12 12:19 ` Peter Zijlstra
@ 2022-03-12 13:34 ` Peter Zijlstra
2022-03-12 15:54 ` [External] " Chengming Zhou
0 siblings, 1 reply; 7+ messages in thread
From: Peter Zijlstra @ 2022-03-12 13:34 UTC (permalink / raw)
To: Chengming Zhou
Cc: tj, lizefan.x, hannes, cgroups, linux-kernel, songmuchun,
Linux Kernel Functional Testing, syzbot+16e3f2c77e7c5a0113f9,
Zhouyi Zhou
On Sat, Mar 12, 2022 at 01:19:13PM +0100, Peter Zijlstra wrote:
> On Sat, Mar 05, 2022 at 11:41:03AM +0800, Chengming Zhou wrote:
> > task_css_set_check() will use rcu_dereference_check() to check for
> > rcu_read_lock_held() on the read-side, which is not true after commit
> > dc6e0818bc9a ("sched/cpuacct: Optimize away RCU read lock"). This
> > commit drop explicit rcu_read_lock(), change to RCU-sched read-side
> > critical section. So fix the RCU warning by adding check for
> > rcu_read_lock_sched_held().
> >
> > Fixes: dc6e0818bc9a ("sched/cpuacct: Optimize away RCU read lock")
> > Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
> > Reported-by: syzbot+16e3f2c77e7c5a0113f9@syzkaller.appspotmail.com
> > Tested-by: Zhouyi Zhou <zhouzhouyi@gmail.com>
> > Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
>
> Thanks, I'll go stick this in sched/core so it's in the same branch that
> caused the problem.
FWIW I never saw this patch because it doesn't instantly look like a
patch I should be interested in. It's classified as 'for-next' and I
don't run -next, sfr does that. Then it's tagged as cgroup, which I also
don't do.
Nowhere does that look like a patch that wants to go in sched/core and
fixes a cpuacct issue.
On top of that, I still don't agree with this, I really think
rcu_dereference_check() itself should be changed.
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [External] Re: [PATCH linux-next] cgroup: fix suspicious rcu_dereference_check() usage warning
2022-03-12 13:34 ` Peter Zijlstra
@ 2022-03-12 15:54 ` Chengming Zhou
0 siblings, 0 replies; 7+ messages in thread
From: Chengming Zhou @ 2022-03-12 15:54 UTC (permalink / raw)
To: Peter Zijlstra
Cc: tj, lizefan.x, hannes, cgroups, linux-kernel, songmuchun,
Linux Kernel Functional Testing, syzbot+16e3f2c77e7c5a0113f9,
Zhouyi Zhou
On 2022/3/12 9:34 下午, Peter Zijlstra wrote:
> On Sat, Mar 12, 2022 at 01:19:13PM +0100, Peter Zijlstra wrote:
>> On Sat, Mar 05, 2022 at 11:41:03AM +0800, Chengming Zhou wrote:
>>> task_css_set_check() will use rcu_dereference_check() to check for
>>> rcu_read_lock_held() on the read-side, which is not true after commit
>>> dc6e0818bc9a ("sched/cpuacct: Optimize away RCU read lock"). This
>>> commit drop explicit rcu_read_lock(), change to RCU-sched read-side
>>> critical section. So fix the RCU warning by adding check for
>>> rcu_read_lock_sched_held().
>>>
>>> Fixes: dc6e0818bc9a ("sched/cpuacct: Optimize away RCU read lock")
>>> Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
>>> Reported-by: syzbot+16e3f2c77e7c5a0113f9@syzkaller.appspotmail.com
>>> Tested-by: Zhouyi Zhou <zhouzhouyi@gmail.com>
>>> Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
>>
>> Thanks, I'll go stick this in sched/core so it's in the same branch that
>> caused the problem.
>
> FWIW I never saw this patch because it doesn't instantly look like a
> patch I should be interested in. It's classified as 'for-next' and I
> don't run -next, sfr does that. Then it's tagged as cgroup, which I also
> don't do.
Oh, sorry for this.. I should've add "cpuacct" in the subject. The
"linux-next" prefix was added because I thought any patch based on
the linux-next branch should add this prefix.
>
> Nowhere does that look like a patch that wants to go in sched/core and
> fixes a cpuacct issue.
>
> On top of that, I still don't agree with this, I really think
> rcu_dereference_check() itself should be changed.
Yes, I think so too. This patch is workaround to fix the warning to
follow the usage in RCU Documentation.
Maybe changes should be made in RCU code to make rcu_dereference_check()
more flexible as you expressed in the conversation with Paul.
Thanks.
^ permalink raw reply [flat|nested] 7+ messages in thread
* [tip: sched/core] cgroup: Fix suspicious rcu_dereference_check() usage warning
2022-03-05 3:41 [PATCH linux-next] cgroup: fix suspicious rcu_dereference_check() usage warning Chengming Zhou
` (2 preceding siblings ...)
2022-03-12 12:19 ` Peter Zijlstra
@ 2022-03-12 12:37 ` tip-bot2 for Chengming Zhou
3 siblings, 0 replies; 7+ messages in thread
From: tip-bot2 for Chengming Zhou @ 2022-03-12 12:37 UTC (permalink / raw)
To: linux-tip-commits
Cc: Linux Kernel Functional Testing, syzbot+16e3f2c77e7c5a0113f9,
Chengming Zhou, Peter Zijlstra (Intel),
Tejun Heo, Zhouyi Zhou, Marek Szyprowski, x86, linux-kernel
The following commit has been merged into the sched/core branch of tip:
Commit-ID: f2aa197e4794bf4c2c0c9570684f86e6fa103e8b
Gitweb: https://git.kernel.org/tip/f2aa197e4794bf4c2c0c9570684f86e6fa103e8b
Author: Chengming Zhou <zhouchengming@bytedance.com>
AuthorDate: Sat, 05 Mar 2022 11:41:03 +08:00
Committer: Peter Zijlstra <peterz@infradead.org>
CommitterDate: Sat, 12 Mar 2022 13:22:11 +01:00
cgroup: Fix suspicious rcu_dereference_check() usage warning
task_css_set_check() will use rcu_dereference_check() to check for
rcu_read_lock_held() on the read-side, which is not true after commit
dc6e0818bc9a ("sched/cpuacct: Optimize away RCU read lock"). This
commit drop explicit rcu_read_lock(), change to RCU-sched read-side
critical section. So fix the RCU warning by adding check for
rcu_read_lock_sched_held().
Fixes: dc6e0818bc9a ("sched/cpuacct: Optimize away RCU read lock")
Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
Reported-by: syzbot+16e3f2c77e7c5a0113f9@syzkaller.appspotmail.com
Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Tejun Heo <tj@kernel.org>
Tested-by: Zhouyi Zhou <zhouzhouyi@gmail.com>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20220305034103.57123-1-zhouchengming@bytedance.com
---
include/linux/cgroup.h | 1 +
1 file changed, 1 insertion(+)
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 1e356c2..0d1ada8 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -450,6 +450,7 @@ extern struct mutex cgroup_mutex;
extern spinlock_t css_set_lock;
#define task_css_set_check(task, __c) \
rcu_dereference_check((task)->cgroups, \
+ rcu_read_lock_sched_held() || \
lockdep_is_held(&cgroup_mutex) || \
lockdep_is_held(&css_set_lock) || \
((task)->flags & PF_EXITING) || (__c))
^ permalink raw reply related [flat|nested] 7+ messages in thread
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2022-03-05 3:41 [PATCH linux-next] cgroup: fix suspicious rcu_dereference_check() usage warning Chengming Zhou
[not found] ` <CGME20220309071027eucas1p1f066b42f49e524404d898929b60b344f@eucas1p1.samsung.com>
2022-03-09 7:10 ` Marek Szyprowski
2022-03-09 18:10 ` Tejun Heo
2022-03-12 12:19 ` Peter Zijlstra
2022-03-12 13:34 ` Peter Zijlstra
2022-03-12 15:54 ` [External] " Chengming Zhou
2022-03-12 12:37 ` [tip: sched/core] cgroup: Fix " tip-bot2 for Chengming Zhou
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