This is a note to let you know that I've just added the patch titled
sched/deadline: Fix reset_on_fork reporting of DL tasks
to the 5.14-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-deadline-fix-reset_on_fork-reporting-of-dl-tas.patch
and it can be found in the queue-5.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 40e453a354feb2b90cce46de8d665bc62cefd8cc
Author: Quentin Perret <qperret@xxxxxxxxxx>
Date: Tue Jul 27 11:11:01 2021 +0100
sched/deadline: Fix reset_on_fork reporting of DL tasks
[ Upstream commit f95091536f78971b269ec321b057b8d630b0ad8a ]
It is possible for sched_getattr() to incorrectly report the state of
the reset_on_fork flag when called on a deadline task.
Indeed, if the flag was set on a deadline task using sched_setattr()
with flags (SCHED_FLAG_RESET_ON_FORK | SCHED_FLAG_KEEP_PARAMS), then
p->sched_reset_on_fork will be set, but __setscheduler() will bail out
early, which means that the dl_se->flags will not get updated by
__setscheduler_params()->__setparam_dl(). Consequently, if
sched_getattr() is then called on the task, __getparam_dl() will
override kattr.sched_flags with the now out-of-date copy in dl_se->flags
and report the stale value to userspace.
To fix this, make sure to only copy the flags that are relevant to
sched_deadline to and from the dl_se->flags field.
Signed-off-by: Quentin Perret <qperret@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20210727101103.2729607-2-qperret@xxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index aaacd6cfd42f..5cafc642e647 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -2741,7 +2741,7 @@ void __setparam_dl(struct task_struct *p, const struct sched_attr *attr)
dl_se->dl_runtime = attr->sched_runtime;
dl_se->dl_deadline = attr->sched_deadline;
dl_se->dl_period = attr->sched_period ?: dl_se->dl_deadline;
- dl_se->flags = attr->sched_flags;
+ dl_se->flags = attr->sched_flags & SCHED_DL_FLAGS;
dl_se->dl_bw = to_ratio(dl_se->dl_period, dl_se->dl_runtime);
dl_se->dl_density = to_ratio(dl_se->dl_deadline, dl_se->dl_runtime);
}
@@ -2754,7 +2754,8 @@ void __getparam_dl(struct task_struct *p, struct sched_attr *attr)
attr->sched_runtime = dl_se->dl_runtime;
attr->sched_deadline = dl_se->dl_deadline;
attr->sched_period = dl_se->dl_period;
- attr->sched_flags = dl_se->flags;
+ attr->sched_flags &= ~SCHED_DL_FLAGS;
+ attr->sched_flags |= dl_se->flags;
}
/*
@@ -2851,7 +2852,7 @@ bool dl_param_changed(struct task_struct *p, const struct sched_attr *attr)
if (dl_se->dl_runtime != attr->sched_runtime ||
dl_se->dl_deadline != attr->sched_deadline ||
dl_se->dl_period != attr->sched_period ||
- dl_se->flags != attr->sched_flags)
+ dl_se->flags != (attr->sched_flags & SCHED_DL_FLAGS))
return true;
return false;
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index ddefb0419d7a..d53d19770866 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -227,6 +227,8 @@ static inline void update_avg(u64 *avg, u64 sample)
*/
#define SCHED_FLAG_SUGOV 0x10000000
+#define SCHED_DL_FLAGS (SCHED_FLAG_RECLAIM | SCHED_FLAG_DL_OVERRUN | SCHED_FLAG_SUGOV)
+
static inline bool dl_entity_is_special(struct sched_dl_entity *dl_se)
{
#ifdef CONFIG_CPU_FREQ_GOV_SCHEDUTIL
