From: tip-bot for Steven Rostedt <rostedt@goodmis.org>
To: linux-tip-commits@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@redhat.com,
peterz@infradead.org, paulmck@linux.vnet.ibm.com,
rostedt@goodmis.org, habanero@linux.vnet.ibm.com,
tglx@linutronix.de, mingo@elte.hu
Subject: [tip:sched/urgent] sched: Check if lowest_mask is initialized in find_lowest_rq()
Date: Wed, 15 Jun 2011 09:50:50 GMT [thread overview]
Message-ID: <tip-0da938c44921cfb690283d3b0c9c48a10375db2c@git.kernel.org> (raw)
In-Reply-To: <20110614223657.824872966@goodmis.org>
Commit-ID: 0da938c44921cfb690283d3b0c9c48a10375db2c
Gitweb: http://git.kernel.org/tip/0da938c44921cfb690283d3b0c9c48a10375db2c
Author: Steven Rostedt <rostedt@goodmis.org>
AuthorDate: Tue, 14 Jun 2011 18:36:25 -0400
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Wed, 15 Jun 2011 11:44:48 +0200
sched: Check if lowest_mask is initialized in find_lowest_rq()
On system boot up, the lowest_mask is initialized with an
early_initcall(). But RT tasks may wake up on other
early_initcall() callers before the lowest_mask is initialized,
causing a system crash.
Commit "d72bce0e67 rcu: Cure load woes" was the first commit
to wake up RT tasks in early init. Before this commit this bug
should not happen.
Reported-by: Andrew Theurer <habanero@linux.vnet.ibm.com>
Tested-by: Andrew Theurer <habanero@linux.vnet.ibm.com>
Tested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20110614223657.824872966@goodmis.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
kernel/sched_rt.c | 4 ++++
1 files changed, 4 insertions(+), 0 deletions(-)
diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
index 9b8d5dc..10d0182 100644
--- a/kernel/sched_rt.c
+++ b/kernel/sched_rt.c
@@ -1239,6 +1239,10 @@ static int find_lowest_rq(struct task_struct *task)
int this_cpu = smp_processor_id();
int cpu = task_cpu(task);
+ /* Make sure the mask is initialized first */
+ if (unlikely(!lowest_mask))
+ return -1;
+
if (task->rt.nr_cpus_allowed == 1)
return -1; /* No other targets possible */
prev parent reply other threads:[~2011-06-15 9:51 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-06-14 22:36 [PATCH 0/2] [GIT PULL][v3.0] sched: various fixes Steven Rostedt
2011-06-14 22:36 ` [PATCH 1/2] sched: Fix need_resched() when checking peempt Steven Rostedt
2011-06-15 9:50 ` [tip:sched/urgent] " tip-bot for Hillf Danton
2011-06-14 22:36 ` [PATCH 2/2] sched: Check if lowest_mask is initialized in find_lowest_rq Steven Rostedt
2011-06-15 0:40 ` Paul E. McKenney
2011-06-15 8:17 ` Peter Zijlstra
2011-06-15 9:50 ` tip-bot for Steven Rostedt [this message]
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=tip-0da938c44921cfb690283d3b0c9c48a10375db2c@git.kernel.org \
--to=rostedt@goodmis.org \
--cc=habanero@linux.vnet.ibm.com \
--cc=hpa@zytor.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-tip-commits@vger.kernel.org \
--cc=mingo@elte.hu \
--cc=mingo@redhat.com \
--cc=paulmck@linux.vnet.ibm.com \
--cc=peterz@infradead.org \
--cc=tglx@linutronix.de \
/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).