From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Vincent Guittot <vincent.guittot@linaro.org>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>, Ben Segall <bsegall@google.com>,
Sasha Levin <sashal@kernel.org>
Subject: [PATCH AUTOSEL 5.4 05/50] sched/fair: Prevent unlimited runtime on throttled group
Date: Sat, 22 Feb 2020 21:21:50 -0500 [thread overview]
Message-ID: <20200223022235.1404-5-sashal@kernel.org> (raw)
In-Reply-To: <20200223022235.1404-1-sashal@kernel.org>
From: Vincent Guittot <vincent.guittot@linaro.org>
[ Upstream commit 2a4b03ffc69f2dedc6388e9a6438b5f4c133a40d ]
When a running task is moved on a throttled task group and there is no
other task enqueued on the CPU, the task can keep running using 100% CPU
whatever the allocated bandwidth for the group and although its cfs rq is
throttled. Furthermore, the group entity of the cfs_rq and its parents are
not enqueued but only set as curr on their respective cfs_rqs.
We have the following sequence:
sched_move_task
-dequeue_task: dequeue task and group_entities.
-put_prev_task: put task and group entities.
-sched_change_group: move task to new group.
-enqueue_task: enqueue only task but not group entities because cfs_rq is
throttled.
-set_next_task : set task and group_entities as current sched_entity of
their cfs_rq.
Another impact is that the root cfs_rq runnable_load_avg at root rq stays
null because the group_entities are not enqueued. This situation will stay
the same until an "external" event triggers a reschedule. Let trigger it
immediately instead.
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Ben Segall <bsegall@google.com>
Link: https://lkml.kernel.org/r/1579011236-31256-1-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
kernel/sched/core.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index a6eeca7021621..be146a1220e33 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -7057,8 +7057,15 @@ void sched_move_task(struct task_struct *tsk)
if (queued)
enqueue_task(rq, tsk, queue_flags);
- if (running)
+ if (running) {
set_next_task(rq, tsk);
+ /*
+ * After changing group, the running task may have joined a
+ * throttled one but it's still the running task. Trigger a
+ * resched to make sure that task can still run.
+ */
+ resched_curr(rq);
+ }
task_rq_unlock(rq, tsk, &rf);
}
--
2.20.1
next prev parent reply other threads:[~2020-02-23 2:22 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-23 2:21 [PATCH AUTOSEL 5.4 01/50] ipmi:ssif: Handle a possible NULL pointer reference Sasha Levin
2020-02-23 2:21 ` [PATCH AUTOSEL 5.4 02/50] drm/msm: Set dma maximum segment size for mdss Sasha Levin
2020-02-23 2:21 ` [PATCH AUTOSEL 5.4 03/50] sched/core: Don't skip remote tick for idle CPUs Sasha Levin
2020-02-23 2:21 ` [PATCH AUTOSEL 5.4 04/50] timers/nohz: Update NOHZ load in remote tick Sasha Levin
2020-02-23 2:21 ` Sasha Levin [this message]
2020-02-23 2:21 ` [PATCH AUTOSEL 5.4 06/50] dax: pass NOWAIT flag to iomap_apply Sasha Levin
2020-02-23 2:21 ` [PATCH AUTOSEL 5.4 07/50] mac80211: consider more elements in parsing CRC Sasha Levin
2020-02-23 2:21 ` [PATCH AUTOSEL 5.4 08/50] cfg80211: check wiphy driver existence for drvinfo report Sasha Levin
2020-02-23 2:21 ` [PATCH AUTOSEL 5.4 09/50] s390/zcrypt: fix card and queue total counter wrap Sasha Levin
2020-02-23 2:21 ` [PATCH AUTOSEL 5.4 10/50] qmi_wwan: re-add DW5821e pre-production variant Sasha Levin
2020-02-23 2:21 ` [PATCH AUTOSEL 5.4 11/50] qmi_wwan: unconditionally reject 2 ep interfaces Sasha Levin
2020-02-23 2:21 ` [PATCH AUTOSEL 5.4 12/50] NFSv4: Fix races between open and dentry revalidation Sasha Levin
2020-02-23 2:21 ` [PATCH AUTOSEL 5.4 13/50] perf/smmuv3: Use platform_get_irq_optional() for wired interrupt Sasha Levin
2020-02-23 2:21 ` [PATCH AUTOSEL 5.4 14/50] arm/ftrace: Fix BE text poking Sasha Levin
2020-02-23 2:22 ` [PATCH AUTOSEL 5.4 15/50] sched/psi: Fix OOB write when writing 0 bytes to PSI files Sasha Levin
2020-02-23 2:22 ` [PATCH AUTOSEL 5.4 16/50] perf/x86/intel: Add Elkhart Lake support Sasha Levin
2020-02-23 2:22 ` [PATCH AUTOSEL 5.4 17/50] perf/x86/cstate: Add Tremont support Sasha Levin
2020-02-23 2:22 ` [PATCH AUTOSEL 5.4 18/50] perf/x86/msr: " Sasha Levin
2020-02-23 2:22 ` [PATCH AUTOSEL 5.4 19/50] ceph: do not execute direct write in parallel if O_APPEND is specified Sasha Levin
2020-02-23 2:22 ` [PATCH AUTOSEL 5.4 20/50] ARM: dts: sti: fixup sound frame-inversion for stihxxx-b2120.dtsi Sasha Levin
2020-02-23 2:22 ` [PATCH AUTOSEL 5.4 21/50] drm/amd/display: Do not set optimized_require to false after plane disable Sasha Levin
2020-02-23 2:22 ` [PATCH AUTOSEL 5.4 22/50] RDMA/siw: Remove unwanted WARN_ON in siw_cm_llp_data_ready() Sasha Levin
2020-02-23 2:22 ` [PATCH AUTOSEL 5.4 23/50] drm/amd/display: Check engine is not NULL before acquiring Sasha Levin
2020-02-23 2:22 ` [PATCH AUTOSEL 5.4 24/50] drm/amd/display: Limit minimum DPPCLK to 100MHz Sasha Levin
2020-02-23 2:22 ` [PATCH AUTOSEL 5.4 25/50] drm/amd/display: Add initialitions for PLL2 clock source Sasha Levin
2020-02-23 2:22 ` [PATCH AUTOSEL 5.4 26/50] amdgpu: Prevent build errors regarding soft/hard-float FP ABI tags Sasha Levin
2020-02-23 2:22 ` [PATCH AUTOSEL 5.4 27/50] soc/tegra: fuse: Fix build with Tegra194 configuration Sasha Levin
2020-02-23 2:22 ` [PATCH AUTOSEL 5.4 28/50] i40e: Fix the conditional for i40e_vc_validate_vqs_bitmaps Sasha Levin
2020-02-23 2:22 ` [PATCH AUTOSEL 5.4 29/50] net: ena: fix potential crash when rxfh key is NULL Sasha Levin
2020-02-23 2:22 ` [PATCH AUTOSEL 5.4 30/50] net: ena: fix uses of round_jiffies() Sasha Levin
2020-02-23 2:22 ` [PATCH AUTOSEL 5.4 31/50] net: ena: add missing ethtool TX timestamping indication Sasha Levin
2020-02-23 2:22 ` [PATCH AUTOSEL 5.4 32/50] net: ena: fix incorrect default RSS key Sasha Levin
2020-02-23 2:22 ` [PATCH AUTOSEL 5.4 33/50] net: ena: rss: do not allocate key when not supported Sasha Levin
2020-02-23 2:22 ` [PATCH AUTOSEL 5.4 34/50] net: ena: rss: fix failure to get indirection table Sasha Levin
2020-02-23 2:22 ` [PATCH AUTOSEL 5.4 35/50] net: ena: rss: store hash function as values and not bits Sasha Levin
2020-02-23 2:22 ` [PATCH AUTOSEL 5.4 36/50] net: ena: fix incorrectly saving queue numbers when setting RSS indirection table Sasha Levin
2020-02-23 2:22 ` [PATCH AUTOSEL 5.4 37/50] net: ena: fix corruption of dev_idx_to_host_tbl Sasha Levin
2020-02-23 2:22 ` [PATCH AUTOSEL 5.4 38/50] net: ena: ethtool: use correct value for crc32 hash Sasha Levin
2020-02-23 2:22 ` [PATCH AUTOSEL 5.4 39/50] net: ena: ena-com.c: prevent NULL pointer dereference Sasha Levin
2020-02-23 2:22 ` [PATCH AUTOSEL 5.4 40/50] enic: prevent waking up stopped tx queues over watchdog reset Sasha Levin
2020-02-23 2:22 ` [PATCH AUTOSEL 5.4 41/50] ice: update Unit Load Status bitmask to check after reset Sasha Levin
2020-02-23 2:22 ` [PATCH AUTOSEL 5.4 42/50] cifs: Fix mode output in debugging statements Sasha Levin
2020-02-23 2:22 ` [PATCH AUTOSEL 5.4 43/50] bcache: ignore pending signals when creating gc and allocator thread Sasha Levin
2020-02-23 2:22 ` [PATCH AUTOSEL 5.4 44/50] cfg80211: add missing policy for NL80211_ATTR_STATUS_CODE Sasha Levin
2020-02-23 2:22 ` [PATCH AUTOSEL 5.4 45/50] mac80211: fix wrong 160/80+80 MHz setting Sasha Levin
2020-02-23 2:22 ` [PATCH AUTOSEL 5.4 46/50] net: hns3: add management table after IMP reset Sasha Levin
2020-02-23 2:22 ` [PATCH AUTOSEL 5.4 47/50] net: hns3: fix a copying IPv6 address error in hclge_fd_get_flow_tuples() Sasha Levin
2020-02-23 2:22 ` [PATCH AUTOSEL 5.4 48/50] nvme/tcp: fix bug on double requeue when send fails Sasha Levin
2020-02-23 2:22 ` [PATCH AUTOSEL 5.4 49/50] nvme: prevent warning triggered by nvme_stop_keep_alive Sasha Levin
2020-02-23 2:22 ` [PATCH AUTOSEL 5.4 50/50] nvme/pci: move cqe check after device shutdown Sasha Levin
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