Messages in this thread Patch in this message | | | Date | Wed, 3 Dec 2008 11:48:28 -0800 | From | Greg KH <> | Subject | [patch 007/104] cpuset: fix regression when failed to generate sched domains |
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2.6.27-stable review patch. If anyone has any objections, please let us know.
------------------ From: Li Zefan <lizf@cn.fujitsu.com>
commit 700018e0a77b4113172257fcdaa1c58e27a5074f upstream.
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 dfb512ec4834116124da61d6c1ee10fd0aa32bd6 | 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> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- kernel/cpuset.c | 12 ++++++++---- kernel/sched.c | 13 +++++++------ 2 files changed, 15 insertions(+), 10 deletions(-)
--- a/kernel/cpuset.c +++ b/kernel/cpuset.c @@ -587,7 +587,6 @@ static int generate_sched_domains(cpumas 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; --- a/kernel/sched.c +++ b/kernel/sched.c @@ -7692,13 +7692,14 @@ static int dattrs_equal(struct sched_dom * * 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 */
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