[PATCH] cpuset : Handling improper memory allocation.

[PATCH] cpuset : Handling improper memory allocation.

[Rakib Mullick]

This patch makes sure that , if kmalloc fails in
"rebuild_sched_domains", then we've a place to go. If anything else,
please let me know.

Thanks.

Signed-off-by: Md.Rakib H. Mullick (rakib.mullick@gmail.com)

--- linux-2.6.27-rc2.orig/kernel/cpuset.c	2008-08-06 16:23:26.000000000 +0600
+++ linux-2.6.27-rc2/kernel/cpuset.c	2008-08-06 23:07:59.504441992 +0600
@@ -615,7 +615,8 @@ void rebuild_sched_domains(void)
 		if (dattr) {
 			*dattr = SD_ATTR_INIT;
 			update_domain_attr_tree(dattr, &top_cpuset);
-		}
+		} else
+			goto rebuild;
 		*doms = top_cpuset.cpus_allowed;
 		goto rebuild;
 	}
@@ -685,6 +686,8 @@ restart:
 	if (!doms)
 		goto rebuild;
 	dattr = kmalloc(ndoms * sizeof(struct sched_domain_attr), GFP_KERNEL);
+	if (!dattr)
+		goto rebuild;

 	for (nslot = 0, i = 0; i < csn; i++) {
 		struct cpuset *a = csa[i];

Re: [PATCH] cpuset : Handling improper memory allocation.

[Max Krasnyansky]

Rakib Mullick wrote:
> This patch makes sure that , if kmalloc fails in
> "rebuild_sched_domains", then we've a place to go. If anything else,
> please let me know.
> 

partition_sched_domains() can deal with attrs==NULL case. So we do not
have to abort domain building.

Max


> Thanks.
> 
> Signed-off-by: Md.Rakib H. Mullick (rakib.mullick@gmail.com)
> 
> --- linux-2.6.27-rc2.orig/kernel/cpuset.c	2008-08-06 16:23:26.000000000 +0600
> +++ linux-2.6.27-rc2/kernel/cpuset.c	2008-08-06 23:07:59.504441992 +0600
> @@ -615,7 +615,8 @@ void rebuild_sched_domains(void)
>  		if (dattr) {
>  			*dattr = SD_ATTR_INIT;
>  			update_domain_attr_tree(dattr, &top_cpuset);
> -		}
> +		} else
> +			goto rebuild;
>  		*doms = top_cpuset.cpus_allowed;
>  		goto rebuild;
>  	}
> @@ -685,6 +686,8 @@ restart:
>  	if (!doms)
>  		goto rebuild;
>  	dattr = kmalloc(ndoms * sizeof(struct sched_domain_attr), GFP_KERNEL);
> +	if (!dattr)
> +		goto rebuild;
> 
>  	for (nslot = 0, i = 0; i < csn; i++) {
>  		struct cpuset *a = csa[i];
> --
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Re: [PATCH] cpuset : Handling improper memory allocation.

[Paul Jackson]

Max wrote:
> partition_sched_domains() can deal with attrs==NULL case. So we do not
> have to abort domain building.

This might be a good place for a comment, since unchecked kmalloc()
calls look dangerous:

	/* Convert <csn, csa> to <ndoms, doms> */
	doms = kmalloc(ndoms * sizeof(cpumask_t), GFP_KERNEL);
	if (!doms)
		goto rebuild;
	dattr = kmalloc(ndoms * sizeof(struct sched_domain_attr), GFP_KERNEL);
	/* dattr == NULL is ok; partition_sched_domains() can cope with it. */

-- 
                  I won't rest till it's the best ...
                  Programmer, Linux Scalability
                  Paul Jackson <pj@sgi.com> 1.940.382.4214

Re: [PATCH] cpuset : Handling improper memory allocation.

[Max Krasnyansky]

Paul Jackson wrote:
> Max wrote:
>> partition_sched_domains() can deal with attrs==NULL case. So we do not
>> have to abort domain building.
> 
> This might be a good place for a comment, since unchecked kmalloc()
> calls look dangerous:
> 
> 	/* Convert <csn, csa> to <ndoms, doms> */
> 	doms = kmalloc(ndoms * sizeof(cpumask_t), GFP_KERNEL);
> 	if (!doms)
> 		goto rebuild;
> 	dattr = kmalloc(ndoms * sizeof(struct sched_domain_attr), GFP_KERNEL);
> 	/* dattr == NULL is ok; partition_sched_domains() can cope with it. */

Makes sense. I'll add it, since I'm touching that area anyway.

Max