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authorLi Zefan <lizefan@huawei.com>2013-04-27 06:52:43 -0700
committerTejun Heo <tj@kernel.org>2013-04-27 06:52:43 -0700
commit5b16c2a493fe1e439c4e7ad51f58153968ca6cf3 (patch)
tree82ed118dcd768f713b96ca055200c341ee02baeb /kernel/cpuset.c
parente0e80a02e5701c8790bd348ab59edb154fbda60b (diff)
cpuset: fix cpu hotplug vs rebuild_sched_domains() race
rebuild_sched_domains() might pass doms with offlined cpu to partition_sched_domains(), which results in an oops: general protection fault: 0000 [#1] SMP ... RIP: 0010:[<ffffffff81077a1e>] [<ffffffff81077a1e>] get_group+0x6e/0x90 ... Call Trace: [<ffffffff8107f07c>] build_sched_domains+0x70c/0xcb0 [<ffffffff8107f2a7>] ? build_sched_domains+0x937/0xcb0 [<ffffffff81173f64>] ? kfree+0xe4/0x1b0 [<ffffffff8107f6e0>] ? partition_sched_domains+0xc0/0x470 [<ffffffff8107f905>] partition_sched_domains+0x2e5/0x470 [<ffffffff8107f6e0>] ? partition_sched_domains+0xc0/0x470 [<ffffffff810c9007>] ? generate_sched_domains+0xc7/0x530 [<ffffffff810c94a8>] rebuild_sched_domains_locked+0x38/0x70 [<ffffffff810cb4a4>] cpuset_write_resmask+0x1a4/0x500 [<ffffffff810c8700>] ? cpuset_mount+0xe0/0xe0 [<ffffffff810c7f50>] ? cpuset_read_u64+0x100/0x100 [<ffffffff810be890>] ? cgroup_iter_next+0x90/0x90 [<ffffffff810cb300>] ? cpuset_css_offline+0x70/0x70 [<ffffffff810c1a73>] cgroup_file_write+0x133/0x2e0 [<ffffffff8118995b>] vfs_write+0xcb/0x130 [<ffffffff8118a174>] sys_write+0x64/0xa0 Reported-by: Li Zhong <zhong@linux.vnet.ibm.com> Signed-off-by: Li Zefan <lizefan@huawei.com> Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'kernel/cpuset.c')
-rw-r--r--kernel/cpuset.c10
1 files changed, 9 insertions, 1 deletions
diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 8f0f45e002f2..93d140f159cc 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -769,12 +769,20 @@ static void rebuild_sched_domains_locked(void)
lockdep_assert_held(&cpuset_mutex);
get_online_cpus();
+ /*
+ * We have raced with CPU hotplug. Don't do anything to avoid
+ * passing doms with offlined cpu to partition_sched_domains().
+ * Anyways, hotplug work item will rebuild sched domains.
+ */
+ if (!cpumask_equal(top_cpuset.cpus_allowed, cpu_active_mask))
+ goto out;
+
/* Generate domain masks and attrs */
ndoms = generate_sched_domains(&doms, &attr);
/* Have scheduler rebuild the domains */
partition_sched_domains(ndoms, doms, attr);
-
+out:
put_online_cpus();
}
#else /* !CONFIG_SMP */