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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 dfb512ec48
| 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: Li Zefan <lizf@cn.fujitsu.com>
Cc: Max Krasnyansky <maxk@qualcomm.com>
Cc: <stable@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Li Zefan 2008-11-18 14:02:03 +08:00 committed by Ingo Molnar
parent ad133ba3dc
commit 700018e0a7
2 changed files with 15 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
kernel/cpuset.c
View File

@ -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;

13
kernel/sched.c
View File

@ -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.
* If doms_new == NULL it will be replaced with cpu_online_map.
* ndoms_new == 0 is a special case for destroying existing domains,
* and it will not create the default domain.
*
* Call with hotplug lock held
*/