This is a note to let you know that I've just added the patch titled
sched/fair: Update rq clock before changing a task's CPU affinity
to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
sched-fair-update-rq-clock-before-changing-a-task-s-cpu-affinity.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Thu Oct 19 15:04:02 CEST 2017
From: Wanpeng Li <wanpeng.li@xxxxxxxxxxx>
Date: Tue, 21 Feb 2017 23:52:55 -0800
Subject: sched/fair: Update rq clock before changing a task's CPU affinity
From: Wanpeng Li <wanpeng.li@xxxxxxxxxxx>
[ Upstream commit a499c3ead88ccf147fc50689e85a530ad923ce36 ]
This is triggered during boot when CONFIG_SCHED_DEBUG is enabled:
------------[ cut here ]------------
WARNING: CPU: 6 PID: 81 at kernel/sched/sched.h:812 set_next_entity+0x11d/0x380
rq->clock_update_flags < RQCF_ACT_SKIP
CPU: 6 PID: 81 Comm: torture_shuffle Not tainted 4.10.0+ #1
Hardware name: LENOVO ThinkCentre M8500t-N000/SHARKBAY, BIOS FBKTC1AUS 02/16/2016
Call Trace:
dump_stack+0x85/0xc2
__warn+0xcb/0xf0
warn_slowpath_fmt+0x5f/0x80
set_next_entity+0x11d/0x380
set_curr_task_fair+0x2b/0x60
do_set_cpus_allowed+0x139/0x180
__set_cpus_allowed_ptr+0x113/0x260
set_cpus_allowed_ptr+0x10/0x20
torture_shuffle+0xfd/0x180
kthread+0x10f/0x150
? torture_shutdown_init+0x60/0x60
? kthread_create_on_node+0x60/0x60
ret_from_fork+0x31/0x40
---[ end trace dd94d92344cea9c6 ]---
The task is running && !queued, so there is no rq clock update before calling
set_curr_task().
This patch fixes it by updating rq clock after holding rq->lock/pi_lock
just as what other dequeue + put_prev + enqueue + set_curr story does.
Signed-off-by: Wanpeng Li <wanpeng.li@xxxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Reviewed-by: Matt Fleming <matt@xxxxxxxxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Mike Galbraith <efault@xxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/1487749975-5994-1-git-send-email-wanpeng.li@xxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/sched/core.c | 1 +
1 file changed, 1 insertion(+)
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1141,6 +1141,7 @@ static int __set_cpus_allowed_ptr(struct
int ret = 0;
rq = task_rq_lock(p, &rf);
+ update_rq_clock(rq);
if (p->flags & PF_KTHREAD) {
/*
Patches currently in stable-queue which might be from wanpeng.li@xxxxxxxxxxx are
queue-4.9/sched-fair-update-rq-clock-before-changing-a-task-s-cpu-affinity.patch