答复: [PATCH] sched/numa: fix stale dst_nid used in distance calculation for candidate nodes

["Li,Rongqing" <lirongqing@baidu.com>]

> 
> From: Li RongQing <lirongqing@baidu.com>
> 
> In task_numa_migrate(), when iterating over candidate NUMA nodes to find
> a migration target beyond the preferred node, the distance is computed as:
> 
>   dist = node_distance(env.src_nid, env.dst_nid);
> 
> However, env.dst_nid still holds the value from the previous iteration (or the
> preferred node on the first pass), not the current candidate node 'nid'. The
> corrected distance is only assigned to env.dst_nid, after it has already been
> used for scoring.
> 
> Fix it by computing the distance against the current candidate node:
> 
>   dist = node_distance(env.src_nid, nid);
> 

ping 

[Li,Rongqing] 

> Signed-off-by: Li RongQing <lirongqing@baidu.com>
> ---
>  kernel/sched/fair.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index d78467e..a58c15a
> 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -3319,7 +3319,7 @@ static int task_numa_migrate(struct task_struct
> *p)
>  			if (nid == env.src_nid || nid == p->numa_preferred_nid)
>  				continue;
> 
> -			dist = node_distance(env.src_nid, env.dst_nid);
> +			dist = node_distance(env.src_nid, nid);
>  			if (sched_numa_topology_type == NUMA_BACKPLANE &&
>  						dist != env.dist) {
>  				taskweight = task_weight(p, env.src_nid, dist);
> --
> 2.9.4