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| author |   Peter Zijlstra <peterz@infradead.org> | 2015-02-09 11:53:18 +0100 |
|---|---|---|
| committer |   Ingo Molnar <mingo@kernel.org> | 2015-02-18 16:17:20 +0100 |
| commit | 1fe89e1b6d270aa0d3452c60d38461ea589594e3 (patch) | |
| tree | ed9a44ec4e104281dd17e0be30e7b4525d9b0b51 /kernel/sched/core.c | |
| parent | sched/dl: Do update_rq_clock() in yield_task_dl() (diff) | |
| download | linux-dev-1fe89e1b6d270aa0d3452c60d38461ea589594e3.tar.xz linux-dev-1fe89e1b6d270aa0d3452c60d38461ea589594e3.zip | |
sched/autogroup: Fix failure to set cpu.rt_runtime_us
Because task_group() uses a cache of autogroup_task_group(), whose
output depends on sched_class, switching classes can generate
problems.
In particular, when started as fair, the cache points to the
autogroup, so when switching to RT the tg_rt_schedulable() test fails
for every cpu.rt_{runtime,period}_us change because now the autogroup
has tasks and no runtime.
Furthermore, going back to the previous semantics of varying
task_group() with sched_class has the down-side that the sched_debug
output varies as well, even though the task really is in the
autogroup.
Therefore add an autogroup exception to tg_has_rt_tasks() -- such that
both (all) task_group() usages in sched/core now have one. And remove
all the remnants of the variable task_group() output.
Reported-by: Zefan Li <lizefan@huawei.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <umgwanakikbuti@gmail.com>
Cc: Stefan Bader <stefan.bader@canonical.com>
Fixes: 8323f26ce342 ("sched: Fix race in task_group()")
Link: http://lkml.kernel.org/r/20150209112237.GR5029@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched/core.c')
| -rw-r--r-- | kernel/sched/core.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index daaea922f482..03a67f09404c 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -7577,6 +7577,12 @@ static inline int tg_has_rt_tasks(struct task_group *tg) { struct task_struct *g, *p; + /* + * Autogroups do not have RT tasks; see autogroup_create(). + */ + if (task_group_is_autogroup(tg)) + return 0; + for_each_process_thread(g, p) { if (rt_task(p) && task_group(p) == tg) return 1; |