Re: [PATCH] sched: Use RCU read lock on all calls to dl_bw_of()

2014-10-02 Thread Peter Zijlstra
On Tue, Sep 30, 2014 at 12:23:37PM +0400, Kirill Tkhai wrote: > [PATCH]sched: Use dl_bw_of() under preempt_disable() > > rq->rd is freed using call_rcu_sched(), so rcu_read_lock() to access it > is not enough. We should use either rcu_read_lock_sched() or > preempt_disable(). > > We choose preem

Re: [PATCH] sched: Use RCU read lock on all calls to dl_bw_of()

2014-09-30 Thread Kirill Tkhai
В Пн, 29/09/2014 в 19:00 +0200, Peter Zijlstra пишет: > On Mon, Sep 29, 2014 at 06:54:18PM +0200, Peter Zijlstra wrote: > > On Mon, Sep 29, 2014 at 08:43:47PM +0400, Kirill Tkhai wrote: > > > Thanks for your report. It looks like your fix is not enough, because > > > we check for rcu_read_lock_sche

Re: [PATCH] sched: Use RCU read lock on all calls to dl_bw_of()

2014-09-29 Thread Peter Zijlstra
On Mon, Sep 29, 2014 at 06:54:18PM +0200, Peter Zijlstra wrote: > On Mon, Sep 29, 2014 at 08:43:47PM +0400, Kirill Tkhai wrote: > > Thanks for your report. It looks like your fix is not enough, because > > we check for rcu_read_lock_sched_held() in dl_bw_of(). It still warns > > even if rcu_read_lo

Re: [PATCH] sched: Use RCU read lock on all calls to dl_bw_of()

2014-09-29 Thread Peter Zijlstra
On Mon, Sep 29, 2014 at 08:43:47PM +0400, Kirill Tkhai wrote: > Thanks for your report. It looks like your fix is not enough, because > we check for rcu_read_lock_sched_held() in dl_bw_of(). It still warns > even if rcu_read_lock() is held. > > I used rcu_read_lock_sched_held() because we free roo

Re: [PATCH] sched: Use RCU read lock on all calls to dl_bw_of()

2014-09-29 Thread Kirill Tkhai
Hi, Sasha, В Пн, 29/09/2014 в 11:19 -0400, Sasha Levin пишет: > Commit "sched: Use dl_bw_of() under RCU read lock" has missed a call > to dl_bw_of(), which has now started showing warnings: > > [ 820.960972] === > [ 820.961663] [ INFO: suspicious RCU usage. ] > [ 82