Messages in this thread |  | | Date | Sat, 12 Mar 2022 14:34:45 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH linux-next] cgroup: fix suspicious rcu_dereference_check() usage warning |
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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.
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