From: "Paul E. McKenney" <paulmck@kernel.org>
To: rcu@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com,
rostedt@goodmis.org, Zqiang <qiang1.zhang@intel.com>,
"Paul E . McKenney" <paulmck@kernel.org>
Subject: [PATCH rcu 07/12] rcu/rcuscale: Fix smp_processor_id()-in-preemptible warnings
Date: Mon, 20 Jun 2022 15:58:12 -0700 [thread overview]
Message-ID: <20220620225817.3843106-7-paulmck@kernel.org> (raw)
In-Reply-To: <20220620225814.GA3842995@paulmck-ThinkPad-P17-Gen-1>
From: Zqiang <qiang1.zhang@intel.com>
Systems built with CONFIG_DEBUG_PREEMPT=y can trigger the following
BUG while running the rcuscale performance test:
BUG: using smp_processor_id() in preemptible [00000000] code: rcu_scale_write/69
CPU: 0 PID: 66 Comm: rcu_scale_write Not tainted 5.18.0-rc7-next-20220517-yoctodev-standard+
caller is debug_smp_processor_id+0x17/0x20
Call Trace:
<TASK>
dump_stack_lvl+0x49/0x5e
dump_stack+0x10/0x12
check_preemption_disabled+0xdf/0xf0
debug_smp_processor_id+0x17/0x20
rcu_scale_writer+0x2b5/0x580
kthread+0x177/0x1b0
ret_from_fork+0x22/0x30
</TASK>
Reproduction method:
runqemu kvm slirp nographic qemuparams="-m 4096 -smp 8" bootparams="isolcpus=2,3
nohz_full=2,3 rcu_nocbs=2,3 rcutree.dump_tree=1 rcuscale.shutdown=false
rcuscale.gp_async=true" -d
The problem is that the rcu_scale_writer() kthreads fail to set the
PF_NO_SETAFFINITY flags, which causes is_percpu_thread() to assume
that the kthread's affinity might change at any time, thus the BUG
noted above.
This commit therefore causes rcu_scale_writer() to set PF_NO_SETAFFINITY
in its kthread's ->flags field, thus preventing this BUG.
Signed-off-by: Zqiang <qiang1.zhang@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
kernel/rcu/rcuscale.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/kernel/rcu/rcuscale.c b/kernel/rcu/rcuscale.c
index 277a5bfb37d48..3ef02d4a81085 100644
--- a/kernel/rcu/rcuscale.c
+++ b/kernel/rcu/rcuscale.c
@@ -419,6 +419,7 @@ rcu_scale_writer(void *arg)
VERBOSE_SCALEOUT_STRING("rcu_scale_writer task started");
WARN_ON(!wdpp);
set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids));
+ current->flags |= PF_NO_SETAFFINITY;
sched_set_fifo_low(current);
if (holdoff)
--
2.31.1.189.g2e36527f23
next prev parent reply other threads:[~2022-06-20 23:00 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-20 22:58 [PATCH rcu 0/12] Torture-test updates for v5.20 Paul E. McKenney
2022-06-20 22:58 ` [PATCH rcu 01/12] torture: Make kvm-remote.sh announce which system is being waited on Paul E. McKenney
2022-06-20 22:58 ` [PATCH rcu 02/12] rcu/torture: Change order of warning and trace dump Paul E. McKenney
2022-06-20 22:58 ` [PATCH rcu 03/12] rcutorture: Simplify rcu_torture_read_exit_child() loop Paul E. McKenney
2022-06-20 22:58 ` [PATCH rcu 04/12] rcutorture: Fix memory leak in rcu_test_debug_objects() Paul E. McKenney
2022-06-20 22:58 ` [PATCH rcu 05/12] torture: Adjust to again produce debugging information Paul E. McKenney
2022-06-20 22:58 ` [PATCH rcu 06/12] rcutorture: Make failure indication note reader-batch overflow Paul E. McKenney
2022-06-20 22:58 ` Paul E. McKenney [this message]
2022-06-20 22:58 ` [PATCH rcu 08/12] torture: Create kvm-check-branches.sh output in proper location Paul E. McKenney
2022-06-20 22:58 ` [PATCH rcu 09/12] rcutorture: Fix ksoftirqd boosting timing and iteration Paul E. McKenney
2022-06-20 22:58 ` [PATCH rcu 10/12] rcutorture: Handle failure of memory allocation functions Paul E. McKenney
2022-06-20 22:58 ` [PATCH rcu 11/12] torture: Flush printk() buffers before powering off Paul E. McKenney
2022-06-20 23:23 ` John Ogness
2022-06-20 23:28 ` Paul E. McKenney
2022-06-21 8:09 ` John Ogness
2022-06-21 18:13 ` Paul E. McKenney
2022-06-21 20:52 ` John Ogness
2022-06-21 21:01 ` Paul E. McKenney
2022-06-20 22:58 ` [PATCH rcu 12/12] refscale: Convert test_lock spinlock to raw_spinlock Paul E. McKenney
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=20220620225817.3843106-7-paulmck@kernel.org \
--to=paulmck@kernel.org \
--cc=kernel-team@fb.com \
--cc=linux-kernel@vger.kernel.org \
--cc=qiang1.zhang@intel.com \
--cc=rcu@vger.kernel.org \
--cc=rostedt@goodmis.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