Messages in this thread | | | Date | Fri, 4 Dec 2015 09:09:01 +0100 | From | Ingo Molnar <> | Subject | Re: [PATCH] sched/core: Clear the root_domain cpumasks in init_rootdomain() |
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* 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
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