[ Upstream commit f718faf3940e95d5d34af9041f279f598396ab7d ]
Before commit:
f5d39b020809 ("freezer,sched: Rewrite core freezer logic")
the frozen task stat was reported as 'D' in cgroup v1.
However, after rewriting the core freezer logic, the frozen task stat is
reported as 'R'. This is confusing, especially when a task with stat of
'S' is frozen.
This bug can be reproduced with these steps:
$ cd /sys/fs/cgroup/freezer/
$ mkdir test
$ sleep 1000 &
[1] 739 // task whose stat is 'S'
$ echo 739 > test/cgroup.procs
$ echo FROZEN > test/freezer.state
$ ps -aux | grep 739
root 739 0.1 0.0 8376 1812 pts/0 R 10:56 0:00 sleep 1000
As shown above, a task whose stat is 'S' was changed to 'R' when it was
frozen.
To solve this regression, simply maintain the same reported state as
before the rewrite.
[ mingo: Enhanced the changelog and comments ]
Fixes: f5d39b020809 ("freezer,sched: Rewrite core freezer logic")
Signed-off-by: Chen Ridong <chenridong@huawei.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Michal Koutný <mkoutny@suse.com>
Link: https://lore.kernel.org/r/20241217004818.3200515-1-chenridong@huaweicloud.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 5d69eca542ee17c618f9a55da52191d5e28b435f ]
All classes use sched_entity::exec_start to track runtime and have
copies of the exact same code around to compute runtime.
Collapse all that.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Phil Auld <pauld@redhat.com>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Link: https://lkml.kernel.org/r/54d148a144f26d9559698c4dd82d8859038a7380.1699095159.git.bristot@kernel.org
Stable-dep-of: 0664e2c311b9 ("sched/deadline: Fix warning in migrate_enable for boosted tasks")
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit d844fe65f0957024c3e1b0bf2a0615246184d9bc ]
Both glibc and musl define 'struct sched_param' in sched.h, while kernel
has it in uapi/linux/sched/types.h, making it cumbersome to use
sched_getattr(2) or sched_setattr(2) from userspace.
For example, something like this:
#include <sched.h>
#include <linux/sched/types.h>
struct sched_attr sa;
will result in "error: redefinition of ‘struct sched_param’" (note the
code doesn't need sched_param at all -- it needs struct sched_attr
plus some stuff from sched.h).
The situation is, glibc is not going to provide a wrapper for
sched_{get,set}attr, thus the need to include linux/sched_types.h
directly, which leads to the above problem.
Thus, the userspace is left with a few sub-par choices when it wants to
use e.g. sched_setattr(2), such as maintaining a copy of struct
sched_attr definition, or using some other ugly tricks.
OTOH, 'struct sched_param' is well known, defined in POSIX, and it won't
be ever changed (as that would break backward compatibility).
So, while 'struct sched_param' is indeed part of the kernel uapi,
exposing it the way it's done now creates an issue, and hiding it
(like this patch does) fixes that issue, hopefully without creating
another one: common userspace software rely on libc headers, and as
for "special" software (like libc), it looks like glibc and musl
do not rely on kernel headers for 'struct sched_param' definition
(but let's Cc their mailing lists in case it's otherwise).
The alternative to this patch would be to move struct sched_attr to,
say, linux/sched.h, or linux/sched/attr.h (the new file).
Oh, and here is the previous attempt to fix the issue:
https://lore.kernel.org/all/20200528135552.GA87103@google.com/
While I support Linus arguments, the issue is still here
and needs to be fixed.
[ mingo: Linus is right, this shouldn't be needed - but on the other
hand I agree that this header is not really helpful to
user-space as-is. So let's pretend that
<uapi/linux/sched/types.h> is only about sched_attr, and
call this commit a workaround for user-space breakage
that it in reality is ... Also, remove the Fixes tag. ]
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230808030357.1213829-1-kolyshkin@gmail.com
Stable-dep-of: 0664e2c311b9 ("sched/deadline: Fix warning in migrate_enable for boosted tasks")
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit bfe93930ea1ea3c6c115a7d44af6e4fea609067e ]
Holding a mutex across synchronize_rcu_tasks() and acquiring
that same mutex in code called from do_exit() after its call to
exit_tasks_rcu_start() but before its call to exit_tasks_rcu_stop()
results in deadlock. This is by design, because tasks that are far
enough into do_exit() are no longer present on the tasks list, making
it a bit difficult for RCU Tasks to find them, let alone wait on them
to do a voluntary context switch. However, such deadlocks are becoming
more frequent. In addition, lockdep currently does not detect such
deadlocks and they can be difficult to reproduce.
In addition, if a task voluntarily context switches during that time
(for example, if it blocks acquiring a mutex), then this task is in an
RCU Tasks quiescent state. And with some adjustments, RCU Tasks could
just as well take advantage of that fact.
This commit therefore adds the data structures that will be needed
to rely on these quiescent states and to eliminate these deadlocks.
Link: https://lore.kernel.org/all/20240118021842.290665-1-chenzhongjin@huawei.com/
Reported-by: Chen Zhongjin <chenzhongjin@huawei.com>
Reported-by: Yang Jihong <yangjihong1@huawei.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Tested-by: Yang Jihong <yangjihong1@huawei.com>
Tested-by: Chen Zhongjin <chenzhongjin@huawei.com>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Stable-dep-of: fd70e9f1d85f ("rcu-tasks: Fix access non-existent percpu rtpcp variable in rcu_tasks_need_gpcb()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
task_state_index() ignores uninteresting state flags (such as TASK_FREEZABLE) for most states, but for TASK_IDLE and TASK_RTLOCK_WAIT it does not. So if a task is waiting TASK_IDLE|TASK_FREEZABLE it gets incorrectly reported as TASK_UNINTERRUPTIBLE or "D". (it is planned for nfsd to change to use this state). Fix this by only testing the interesting bits and not the irrelevant bits in __task_state_index() Signed-off-by: NeilBrown <neilb@suse.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/169335025927.5133.4781141800413736103@noble.neil.brown.name
This is an exported symbol, so it should have kernel-doc. Add a note to very similar function do_set_cpus_allowed() to avoid confusion and misuse. Signed-off-by: Costa Shulyupin <costa.shul@redhat.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20230829082551.2661290-1-costa.shul@redhat.com
Where CFS is currently a WFQ based scheduler with only a single knob, the weight. The addition of a second, latency oriented parameter, makes something like WF2Q or EEVDF based a much better fit. Specifically, EEVDF does EDF like scheduling in the left half of the tree -- those entities that are owed service. Except because this is a virtual time scheduler, the deadlines are in virtual time as well, which is what allows over-subscription. EEVDF has two parameters: - weight, or time-slope: which is mapped to nice just as before - request size, or slice length: which is used to compute the virtual deadline as: vd_i = ve_i + r_i/w_i Basically, by setting a smaller slice, the deadline will be earlier and the task will be more eligible and ran earlier. Tick driven preemption is driven by request/slice completion; while wakeup preemption is driven by the deadline. Because the tree is now effectively an interval tree, and the selection is no longer 'leftmost', over-scheduling is less of a problem. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20230531124603.931005524@infradead.org
With the introduction of avg_vruntime, it is possible to approximate lag (the entire purpose of introducing it in fact). Use this to do lag based placement over sleep+wake. Specifically, the FAIR_SLEEPERS thing places things too far to the left and messes up the deadline aspect of EEVDF. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20230531124603.794929315@infradead.org
The rename in 2f064a59a11f ("sched: Change task_struct::state") missed the
comments.
[ mingo: Improved the changelog. ]
Signed-off-by: Chin Yik Ming <yikming2222@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Link: https://lore.kernel.org/r/20230717064952.2804-1-yikming2222@gmail.com
As core scheduling introduced, a new state of idle is defined as force idle, running idle task but nr_running greater than zero. If a cpu is in force idle state, idle_cpu() will return zero. This result makes sense in some scenarios, e.g., load balance, showacpu when dumping, and judge the RCU boost kthread is starving. But this will cause error in other scenarios, e.g., tick_irq_exit(): When force idle, rq->curr == rq->idle but rq->nr_running > 0, results that idle_cpu() returns 0. In function tick_irq_exit(), if idle_cpu() is 0, tick_nohz_irq_exit() will not be called, and ts->idle_active will not become 1, which became 0 in tick_nohz_irq_enter(). ts->idle_sleeptime won't update in function update_ts_time_stats(), if ts->idle_active is 0, which should be 1. And this bug will result that ts->idle_sleeptime is less than the actual value, and finally will result that the idle time in /proc/stat is less than the actual value. To solve this problem, we introduce sched_core_idle_cpu(), which returns 1 when force idle. We audit all users of idle_cpu(), and change idle_cpu() into sched_core_idle_cpu() in function tick_irq_exit(). v2-->v3: Only replace idle_cpu() with sched_core_idle_cpu() in function tick_irq_exit(). And modify the corresponding commit log. Signed-off-by: Cruz Zhao <CruzZhao@linux.alibaba.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Peter Zijlstra <peterz@infradead.org> Reviewed-by: Frederic Weisbecker <frederic@kernel.org> Reviewed-by: Joel Fernandes <joel@joelfernandes.org> Link: https://lore.kernel.org/r/1688011324-42406-1-git-send-email-CruzZhao@linux.alibaba.com