From: Steven Rostedt <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org,
linux-rt-users <linux-rt-users@vger.kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Carsten Emde <C.Emde@osadl.org>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
John Kacur <jkacur@redhat.com>, Daniel Wagner <wagi@monom.org>,
Tom Zanussi <zanussi@kernel.org>,
"Srivatsa S. Bhat" <srivatsa@csail.mit.edu>,
stable@kernel.org,
"Peter Zijlstra (Intel)" <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>,
Valentin Schneider <valentin.schneider@arm.com>,
Paul Gortmaker <paul.gortmaker@windriver.com>
Subject: [PATCH RT 5/8] sched: Fix affine_move_task() self-concurrency
Date: Fri, 09 Jul 2021 17:59:58 -0400 [thread overview]
Message-ID: <20210709220018.003428207@goodmis.org> (raw)
In-Reply-To: 20210709215953.122804544@goodmis.org
5.10.47-rt46-rc1 stable review patch.
If anyone has any objections, please let me know.
------------------
From: Peter Zijlstra <peterz@infradead.org>
commit 9e81889c7648d48dd5fe13f41cbc99f3c362484a upstream.
Consider:
sched_setaffinity(p, X); sched_setaffinity(p, Y);
Then the first will install p->migration_pending = &my_pending; and
issue stop_one_cpu_nowait(pending); and the second one will read
p->migration_pending and _also_ issue: stop_one_cpu_nowait(pending),
the _SAME_ @pending.
This causes stopper list corruption.
Add set_affinity_pending::stop_pending, to indicate if a stopper is in
progress.
Fixes: 6d337eab041d ("sched: Fix migrate_disable() vs set_cpus_allowed_ptr()")
Cc: stable@kernel.org
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Link: https://lkml.kernel.org/r/20210224131355.649146419@infradead.org
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
kernel/sched/core.c | 15 ++++++++++++---
1 file changed, 12 insertions(+), 3 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 9cbe12d8c5bd..20588a59300d 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1900,6 +1900,7 @@ struct migration_arg {
struct set_affinity_pending {
refcount_t refs;
+ unsigned int stop_pending;
struct completion done;
struct cpu_stop_work stop_work;
struct migration_arg arg;
@@ -2018,12 +2019,15 @@ static int migration_cpu_stop(void *data)
* determine is_migration_disabled() and so have to chase after
* it.
*/
+ WARN_ON_ONCE(!pending->stop_pending);
task_rq_unlock(rq, p, &rf);
stop_one_cpu_nowait(task_cpu(p), migration_cpu_stop,
&pending->arg, &pending->stop_work);
return 0;
}
out:
+ if (pending)
+ pending->stop_pending = false;
task_rq_unlock(rq, p, &rf);
if (complete)
@@ -2219,7 +2223,7 @@ static int affine_move_task(struct rq *rq, struct task_struct *p, struct rq_flag
int dest_cpu, unsigned int flags)
{
struct set_affinity_pending my_pending = { }, *pending = NULL;
- bool complete = false;
+ bool stop_pending, complete = false;
/* Can the task run on the task's current CPU? If so, we're done */
if (cpumask_test_cpu(task_cpu(p), &p->cpus_mask)) {
@@ -2292,14 +2296,19 @@ static int affine_move_task(struct rq *rq, struct task_struct *p, struct rq_flag
* anything else we cannot do is_migration_disabled(), punt
* and have the stopper function handle it all race-free.
*/
+ stop_pending = pending->stop_pending;
+ if (!stop_pending)
+ pending->stop_pending = true;
refcount_inc(&pending->refs); /* pending->{arg,stop_work} */
if (flags & SCA_MIGRATE_ENABLE)
p->migration_flags &= ~MDF_PUSH;
task_rq_unlock(rq, p, rf);
- stop_one_cpu_nowait(cpu_of(rq), migration_cpu_stop,
- &pending->arg, &pending->stop_work);
+ if (!stop_pending) {
+ stop_one_cpu_nowait(cpu_of(rq), migration_cpu_stop,
+ &pending->arg, &pending->stop_work);
+ }
if (flags & SCA_MIGRATE_ENABLE)
return 0;
--
2.30.2
next prev parent reply other threads:[~2021-07-09 22:00 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-09 21:59 [PATCH RT 0/8] Linux 5.10.47-rt46-rc1 Steven Rostedt
2021-07-09 21:59 ` [PATCH RT 1/8] sched: Fix migration_cpu_stop() requeueing Steven Rostedt
2021-07-09 21:59 ` [PATCH RT 2/8] sched: Simplify migration_cpu_stop() Steven Rostedt
2021-07-09 21:59 ` [PATCH RT 3/8] sched: Collate affine_move_task() stoppers Steven Rostedt
2021-07-09 21:59 ` [PATCH RT 4/8] sched: Optimize migration_cpu_stop() Steven Rostedt
2021-07-09 21:59 ` Steven Rostedt [this message]
2021-07-25 5:03 ` [PATCH RT 5/8] sched: Fix affine_move_task() self-concurrency Pavel Machek
2021-07-26 13:39 ` Valentin Schneider
2021-07-26 16:07 ` Paul Gortmaker
2021-07-09 21:59 ` [PATCH RT 6/8] sched: Simplify set_affinity_pending refcounts Steven Rostedt
2021-07-09 22:00 ` [PATCH RT 7/8] sched: Dont defer CPU pick to migration_cpu_stop() Steven Rostedt
2021-07-09 22:00 ` [PATCH RT 8/8] Linux 5.10.47-rt46-rc1 Steven Rostedt
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210709220018.003428207@goodmis.org \
--to=rostedt@goodmis.org \
--cc=C.Emde@osadl.org \
--cc=bigeasy@linutronix.de \
--cc=jkacur@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-rt-users@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=paul.gortmaker@windriver.com \
--cc=peterz@infradead.org \
--cc=srivatsa@csail.mit.edu \
--cc=stable@kernel.org \
--cc=tglx@linutronix.de \
--cc=valentin.schneider@arm.com \
--cc=wagi@monom.org \
--cc=zanussi@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).