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sched/numa: Fix boot crash on arm64 systems

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Qian Cai reported a boot crash on arm64 systems, caused by:

  0fb3978b0a ("sched/numa: Fix NUMA topology for systems with CPU-less nodes")

The bug is that node_state() must be supplied a valid node_states[] array index,
but in task_numa_placement() the max_nid search can fail with NUMA_NO_NODE,
which is not a valid index.

Fix it by checking that max_nid is a valid index.

[ mingo: Added changelog. ]

Fixes: 0fb3978b0a ("sched/numa: Fix NUMA topology for systems with CPU-less nodes")
Reported-by: Qian Cai <quic_qiancai@quicinc.com>
Tested-by: Qian Cai <quic_qiancai@quicinc.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Huang, Ying 2022-03-22 08:39:22 +01:00 committed by Ingo Molnar
parent 3387ce4d8a
commit ab31c7fd2d
1 changed files with 1 additions and 1 deletions
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2
kernel/sched/fair.c
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@ -2437,7 +2437,7 @@ static void task_numa_placement(struct task_struct *p)
}
/* Cannot migrate task to CPU-less node */
if (!node_state(max_nid, N_CPU)) {
if (max_nid != NUMA_NO_NODE && !node_state(max_nid, N_CPU)) {
int near_nid = max_nid;
int distance, near_distance = INT_MAX;