From: Ingo Molnar <mingo@kernel.org>
To: Xunlei Pang <xlpang@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
linux-kernel@vger.kernel.org, Ingo Molnar <mingo@redhat.com>,
Steven Rostedt <rostedt@goodmis.org>,
Rusty Russell <rusty@rustcorp.com.au>
Subject: Re: [PATCH] sched/core: Clear the root_domain cpumasks in init_rootdomain()
Date: Fri, 4 Dec 2015 09:09:01 +0100 [thread overview]
Message-ID: <20151204080901.GA26934@gmail.com> (raw)
In-Reply-To: <56602D19.5080308@redhat.com>
* Xunlei Pang <xlpang@redhat.com> wrote:
> > Hm, is the alloc_cpumask_var() done in alloc_sched_domains() safe?
>
> Until now, I haven't found any other similar issues, but I will check further.
>
> >
> > At least the usage pattern in init_sched_domains() looks unsafe:
> >
> > doms_cur = alloc_sched_domains(ndoms_cur);
> > if (!doms_cur)
> > doms_cur = &fallback_doms;
> > cpumask_andnot(doms_cur[0], cpu_map, cpu_isolated_map);
So is this pattern in init_sched_domains() correct, for OFFSTACK=y?
It looks wrong to me, as alloc_sched_domains() allocates an uninitialized cpumask
via alloc_cpumask_var() and returns it:
cpumask_var_t *alloc_sched_domains(unsigned int ndoms)
{
int i;
cpumask_var_t *doms;
doms = kmalloc(sizeof(*doms) * ndoms, GFP_KERNEL);
if (!doms)
return NULL;
for (i = 0; i < ndoms; i++) {
if (!alloc_cpumask_var(&doms[i], GFP_KERNEL)) {
free_sched_domains(doms, i);
return NULL;
}
}
return doms;
}
and then this code:
> > cpumask_andnot(doms_cur[0], cpu_map, cpu_isolated_map);
uses it without first clearing it.
So is this another such bug, or am I missing something?
Thanks,
Ingo
next prev parent reply other threads:[~2015-12-04 8:09 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-02 11:52 [PATCH] sched/core: Clear the root_domain cpumasks in init_rootdomain() Xunlei Pang
2015-12-02 12:34 ` Peter Zijlstra
2015-12-02 13:12 ` Xunlei Pang
2015-12-02 16:25 ` Peter Zijlstra
2015-12-03 2:44 ` Xunlei Pang
2015-12-03 8:28 ` Ingo Molnar
2015-12-03 11:52 ` Xunlei Pang
2015-12-04 8:09 ` Ingo Molnar [this message]
2015-12-04 8:27 ` Peter Zijlstra
2015-12-04 8:30 ` Ingo Molnar
2015-12-04 8:28 ` Xunlei Pang
2015-12-04 8:30 ` Ingo Molnar
2015-12-03 9:35 ` Peter Zijlstra
2015-12-04 11:52 ` [tip:locking/core] " tip-bot for Xunlei Pang
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