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Commit 700018e0 authored by Li Zefan's avatar Li Zefan Committed by Ingo Molnar
Browse files

cpuset: fix regression when failed to generate sched domains 



Impact: properly rebuild sched-domains on kmalloc() failure

When cpuset failed to generate sched domains due to kmalloc()
failure, the scheduler should fallback to the single partition
'fallback_doms' and rebuild sched domains, but now it only
destroys but not rebuilds sched domains.

The regression was introduced by:

| commit dfb512ec
| Author: Max Krasnyansky <maxk@qualcomm.com>
| Date:   Fri Aug 29 13:11:41 2008 -0700
|
|    sched: arch_reinit_sched_domains() must destroy domains to force rebuild

After the above commit, partition_sched_domains(0, NULL, NULL) will
only destroy sched domains and partition_sched_domains(1, NULL, NULL)
will create the default sched domain.

Signed-off-by: default avatarLi Zefan <lizf@cn.fujitsu.com>
Cc: Max Krasnyansky <maxk@qualcomm.com>
Cc: <stable@kernel.org>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent ad133ba3

kernel/cpuset.c

+8 −4
Original line number Diff line number Diff line
@@ -587,7 +587,6 @@ static int generate_sched_domains(cpumask_t **domains, 
	int ndoms;		/* number of sched domains in result */

	int nslot;		/* next empty doms[] cpumask_t slot */



	ndoms = 0;

	doms = NULL;

	dattr = NULL;

	csa = NULL;
@@ -674,10 +673,8 @@ restart: 
	 * Convert <csn, csa> to <ndoms, doms> and populate cpu masks.

	 */

	doms = kmalloc(ndoms * sizeof(cpumask_t), GFP_KERNEL);

	if (!doms) {

		ndoms = 0;

	if (!doms)

		goto done;

	}



	/*

	 * The rest of the code, including the scheduler, can deal with
@@ -732,6 +729,13 @@ restart: 
done:

	kfree(csa);



	/*

	 * Fallback to the default domain if kmalloc() failed.

	 * See comments in partition_sched_domains().

	 */

	if (doms == NULL)

		ndoms = 1;



	*domains    = doms;

	*attributes = dattr;

	return ndoms;

kernel/sched.c

+7 −6
Original line number Diff line number Diff line
@@ -7789,13 +7789,14 @@ static int dattrs_equal(struct sched_domain_attr *cur, int idx_cur, 
 *

 * The passed in 'doms_new' should be kmalloc'd. This routine takes

 * ownership of it and will kfree it when done with it. If the caller

 * failed the kmalloc call, then it can pass in doms_new == NULL,

 * and partition_sched_domains() will fallback to the single partition

 * 'fallback_doms', it also forces the domains to be rebuilt.

 * failed the kmalloc call, then it can pass in doms_new == NULL &&

 * ndoms_new == 1, and partition_sched_domains() will fallback to

 * the single partition 'fallback_doms', it also forces the domains

 * to be rebuilt.

 *

 * If doms_new == NULL it will be replaced with cpu_online_map.

 * ndoms_new==0 is a special case for destroying existing domains.

 * It will not create the default domain.

 * ndoms_new == 0 is a special case for destroying existing domains,

 * and it will not create the default domain.

 *

 * Call with hotplug lock held

 */