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authorIgor Mammedov <imammedo@redhat.com>2012-05-09 12:38:28 +0200
committerIngo Molnar <mingo@kernel.org>2012-05-09 12:27:35 +0200
commit30b4e9eb783d94e9f5d503b15eb31720679ae1c7 (patch)
tree1369b75e45c5eaa1763a87f4e3ce03a9b32737e8
parentfebb72a6e4cc6c8cffcc1ea649a3fb364f1ea432 (diff)
downloadlinux-30b4e9eb783d94e9f5d503b15eb31720679ae1c7.tar.gz
sched: Fix KVM and ia64 boot crash due to sched_groups circular linked list assumption
If we have one cpu that failed to boot and boot cpu gave up on waiting for it and then another cpu is being booted, kernel might crash with following OOPS: BUG: unable to handle kernel NULL pointer dereference at 0000000000000018 IP: [<ffffffff812c3630>] __bitmap_weight+0x30/0x80 Call Trace: [<ffffffff8108b9b6>] build_sched_domains+0x7b6/0xa50 The crash happens in init_sched_groups_power() that expects sched_groups to be circular linked list. However it is not always true, since sched_groups preallocated in __sdt_alloc are initialized in build_sched_groups and it may exit early if (cpu != cpumask_first(sched_domain_span(sd))) return 0; without initializing sd->groups->next field. Fix bug by initializing next field right after sched_group was allocated. Also-Reported-by: Jiang Liu <liuj97@gmail.com> Signed-off-by: Igor Mammedov <imammedo@redhat.com> Cc: a.p.zijlstra@chello.nl Cc: pjt@google.com Cc: seto.hidetoshi@jp.fujitsu.com Link: http://lkml.kernel.org/r/1336559908-32533-1-git-send-email-imammedo@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
-rw-r--r--kernel/sched/core.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 0533a688ce2..e5212ae294f 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6382,6 +6382,8 @@ static int __sdt_alloc(const struct cpumask *cpu_map)
if (!sg)
return -ENOMEM;
+ sg->next = sg;
+
*per_cpu_ptr(sdd->sg, j) = sg;
sgp = kzalloc_node(sizeof(struct sched_group_power),