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SubjectRe: [PATCH] mm/alloc: fallback to first node if the wanted node offline
On Tue, 4 Dec 2018, Pingfan Liu wrote:

> diff --git a/include/linux/gfp.h b/include/linux/gfp.h
> index 76f8db0..8324953 100644
> --- a/include/linux/gfp.h
> +++ b/include/linux/gfp.h
> @@ -453,6 +453,8 @@ static inline int gfp_zonelist(gfp_t flags)
> */
> static inline struct zonelist *node_zonelist(int nid, gfp_t flags)
> {
> + if (unlikely(!node_online(nid)))
> + nid = first_online_node;
> return NODE_DATA(nid)->node_zonelists + gfp_zonelist(flags);
> }
>

So we're passing the node id from dev_to_node() to kmalloc which
interprets that as the preferred node and then does node_zonelist() to
find the zonelist at allocation time.

What happens if we fix this in alloc_dr()? Does anything else cause
problems?

And rather than using first_online_node, would next_online_node() work?

I'm thinking about this:

diff --git a/drivers/base/devres.c b/drivers/base/devres.c
--- a/drivers/base/devres.c
+++ b/drivers/base/devres.c
@@ -100,6 +100,8 @@ static __always_inline struct devres * alloc_dr(dr_release_t release,
&tot_size)))
return NULL;

+ if (unlikely(!node_online(nid)))
+ nid = next_online_node(nid);
dr = kmalloc_node_track_caller(tot_size, gfp, nid);
if (unlikely(!dr))
return NULL;
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