From: "Niklas Söderlund" <niklas.soderlund@ragnatech.se> To: Vincent Guittot <vincent.guittot@linaro.org> Cc: Peter Zijlstra <peterz@infradead.org>, Heiner Kallweit <hkallweit1@gmail.com>, "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>, Ingo Molnar <mingo@redhat.com>, linux-kernel <linux-kernel@vger.kernel.org>, linux-renesas-soc@vger.kernel.org Subject: Re: Potential problem with 31e77c93e432dec7 ("sched/fair: Update blocked load when newly idle") Date: Thu, 26 Apr 2018 17:38:57 +0200 [thread overview] Message-ID: <20180426153857.GG3315@bigcity.dyn.berto.se> (raw) In-Reply-To: <CAKfTPtBpmXieT=0PEmNgTPg=r-zEbvhH-d0_qxC_S2iVUJ7HRw@mail.gmail.com> Hi Vincent, On 2018-04-26 17:27:24 +0200, Vincent Guittot wrote: > Hi Niklas, > > >> Thanks for the trace, I have been able to catch a problem with it. > >> Could you test the patch below to confirm that the problem is solved ? > >> The patch apply on-top of > >> c18bb396d3d261eb ("Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net") > > > > I can confirm that with the patch bellow I can no longer produce the > > problem. Thanks! > > Thanks for testing > Do you mind if I add > Tested-by: Niklas Söderlund <niklas.soderlund@ragnatech.se> Please do. > > Peter, Ingo, > Do you want me to re-send the patch with all tags or you will take > this version ? > > Regards, > Vincent > > > > >> > >> From: Vincent Guittot <vincent.guittot@linaro.org> > >> Date: Thu, 26 Apr 2018 12:19:32 +0200 > >> Subject: [PATCH] sched/fair: fix the update of blocked load when newly idle > >> MIME-Version: 1.0 > >> Content-Type: text/plain; charset=UTF-8 > >> Content-Transfer-Encoding: 8bit > >> > >> With commit 31e77c93e432 ("sched/fair: Update blocked load when newly idle"), > >> we release the rq->lock when updating blocked load of idle CPUs. This open > >> a time window during which another CPU can add a task to this CPU's cfs_rq. > >> The check for newly added task of idle_balance() is not in the common path. > >> Move the out label to include this check. > >> > >> Fixes: 31e77c93e432 ("sched/fair: Update blocked load when newly idle") > >> Reported-by: Heiner Kallweit <hkallweit1@gmail.com> > >> Reported-by: Niklas Söderlund <niklas.soderlund@ragnatech.se> > >> Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> > >> --- > >> kernel/sched/fair.c | 2 +- > >> 1 file changed, 1 insertion(+), 1 deletion(-) > >> > >> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > >> index 0951d1c..15a9f5e 100644 > >> --- a/kernel/sched/fair.c > >> +++ b/kernel/sched/fair.c > >> @@ -9847,6 +9847,7 @@ static int idle_balance(struct rq *this_rq, struct rq_flags *rf) > >> if (curr_cost > this_rq->max_idle_balance_cost) > >> this_rq->max_idle_balance_cost = curr_cost; > >> > >> +out: > >> /* > >> * While browsing the domains, we released the rq lock, a task could > >> * have been enqueued in the meantime. Since we're not going idle, > >> @@ -9855,7 +9856,6 @@ static int idle_balance(struct rq *this_rq, struct rq_flags *rf) > >> if (this_rq->cfs.h_nr_running && !pulled_task) > >> pulled_task = 1; > >> > >> -out: > >> /* Move the next balance forward */ > >> if (time_after(this_rq->next_balance, next_balance)) > >> this_rq->next_balance = next_balance; > >> -- > >> 2.7.4 > >> > >> > >> > >> [snip] > >> > > > > -- > > Regards, > > Niklas Söderlund -- Regards, Niklas Söderlund
WARNING: multiple messages have this Message-ID (diff)
From: "Niklas Söderlund" <niklas.soderlund@ragnatech.se> To: Vincent Guittot <vincent.guittot@linaro.org> Cc: Peter Zijlstra <peterz@infradead.org>, Heiner Kallweit <hkallweit1@gmail.com>, "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>, Ingo Molnar <mingo@redhat.com>, linux-kernel <linux-kernel@vger.kernel.org>, linux-renesas-soc@vger.kernel.org Subject: Re: Potential problem with 31e77c93e432dec7 ("sched/fair: Update blocked load when newly idle") Date: Thu, 26 Apr 2018 17:38:57 +0200 [thread overview] Message-ID: <20180426153857.GG3315@bigcity.dyn.berto.se> (raw) In-Reply-To: <CAKfTPtBpmXieT=0PEmNgTPg=r-zEbvhH-d0_qxC_S2iVUJ7HRw@mail.gmail.com> Hi Vincent, On 2018-04-26 17:27:24 +0200, Vincent Guittot wrote: > Hi Niklas, > > >> Thanks for the trace, I have been able to catch a problem with it. > >> Could you test the patch below to confirm that the problem is solved ? > >> The patch apply on-top of > >> c18bb396d3d261eb ("Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net") > > > > I can confirm that with the patch bellow I can no longer produce the > > problem. Thanks! > > Thanks for testing > Do you mind if I add > Tested-by: Niklas S�derlund <niklas.soderlund@ragnatech.se> Please do. > > Peter, Ingo, > Do you want me to re-send the patch with all tags or you will take > this version ? > > Regards, > Vincent > > > > >> > >> From: Vincent Guittot <vincent.guittot@linaro.org> > >> Date: Thu, 26 Apr 2018 12:19:32 +0200 > >> Subject: [PATCH] sched/fair: fix the update of blocked load when newly idle > >> MIME-Version: 1.0 > >> Content-Type: text/plain; charset=UTF-8 > >> Content-Transfer-Encoding: 8bit > >> > >> With commit 31e77c93e432 ("sched/fair: Update blocked load when newly idle"), > >> we release the rq->lock when updating blocked load of idle CPUs. This open > >> a time window during which another CPU can add a task to this CPU's cfs_rq. > >> The check for newly added task of idle_balance() is not in the common path. > >> Move the out label to include this check. > >> > >> Fixes: 31e77c93e432 ("sched/fair: Update blocked load when newly idle") > >> Reported-by: Heiner Kallweit <hkallweit1@gmail.com> > >> Reported-by: Niklas S�derlund <niklas.soderlund@ragnatech.se> > >> Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> > >> --- > >> kernel/sched/fair.c | 2 +- > >> 1 file changed, 1 insertion(+), 1 deletion(-) > >> > >> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > >> index 0951d1c..15a9f5e 100644 > >> --- a/kernel/sched/fair.c > >> +++ b/kernel/sched/fair.c > >> @@ -9847,6 +9847,7 @@ static int idle_balance(struct rq *this_rq, struct rq_flags *rf) > >> if (curr_cost > this_rq->max_idle_balance_cost) > >> this_rq->max_idle_balance_cost = curr_cost; > >> > >> +out: > >> /* > >> * While browsing the domains, we released the rq lock, a task could > >> * have been enqueued in the meantime. Since we're not going idle, > >> @@ -9855,7 +9856,6 @@ static int idle_balance(struct rq *this_rq, struct rq_flags *rf) > >> if (this_rq->cfs.h_nr_running && !pulled_task) > >> pulled_task = 1; > >> > >> -out: > >> /* Move the next balance forward */ > >> if (time_after(this_rq->next_balance, next_balance)) > >> this_rq->next_balance = next_balance; > >> -- > >> 2.7.4 > >> > >> > >> > >> [snip] > >> > > > > -- > > Regards, > > Niklas S�derlund -- Regards, Niklas S�derlund
next prev parent reply other threads:[~2018-04-26 15:39 UTC|newest] Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-04-12 9:18 Potential problem with 31e77c93e432dec7 ("sched/fair: Update blocked load when newly idle") Niklas Söderlund 2018-04-12 9:18 ` Niklas Söderlund 2018-04-12 10:33 ` Vincent Guittot 2018-04-12 11:15 ` Niklas Söderlund 2018-04-12 11:15 ` Niklas Söderlund [not found] ` <20180412133031.GA551@linaro.org> 2018-04-12 19:43 ` Heiner Kallweit 2018-04-14 11:21 ` Vincent Guittot 2018-04-12 22:39 ` Niklas Söderlund 2018-04-12 22:39 ` Niklas Söderlund 2018-04-14 11:24 ` Vincent Guittot 2018-04-20 16:00 ` Vincent Guittot 2018-04-20 16:00 ` Vincent Guittot 2018-04-20 16:30 ` Joel Fernandes 2018-04-22 22:18 ` Niklas Söderlund 2018-04-22 22:18 ` Niklas Söderlund 2018-04-23 9:54 ` Vincent Guittot 2018-04-23 9:54 ` Vincent Guittot [not found] ` <20180425225603.GA26177@bigcity.dyn.berto.se> 2018-04-26 10:31 ` Vincent Guittot 2018-04-26 10:31 ` Vincent Guittot 2018-04-26 11:48 ` Peter Zijlstra 2018-04-26 11:48 ` Peter Zijlstra 2018-04-26 14:41 ` Niklas Söderlund 2018-04-26 14:41 ` Niklas Söderlund 2018-04-26 15:27 ` Vincent Guittot 2018-04-26 15:38 ` Niklas Söderlund [this message] 2018-04-26 15:38 ` Niklas Söderlund 2018-05-02 13:40 ` Geert Uytterhoeven 2018-05-03 9:25 ` [tip:sched/urgent] sched/fair: Fix the update of blocked load when newly idle tip-bot for Vincent Guittot 2018-04-13 20:38 ` Potential problem with 31e77c93e432dec7 ("sched/fair: Update blocked load when newly idle") Niklas Söderlund 2018-04-13 20:38 ` Niklas Söderlund 2018-04-14 11:26 ` Vincent Guittot 2018-04-12 22:06 ` Niklas Söderlund 2018-04-12 22:06 ` Niklas Söderlund
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